Painting asbestos cement sheets. All about slate paint: how to choose, prepare the surface, paint
Asbestos-cement slate roofs have been used in construction for decades, and slate is the most common roofing material in Russia. Asbestos cement is an artificial stone material obtained by hardening an aqueous mixture of Portland cement and finely fluffed chrysotile asbestos fibers that reinforce the cement component.
Asbestos-cement products have a high mechanical strength when bending, low density, low thermal conductivity and water permeability, high frost resistance, resistance to alkalis, and are also characterized by sufficient biostability. Tensile strength of asbestos-cement slate sheet: in tension - 20...25 MPa, in bending - 27...42 MPa, in compression - 45 MPa or more.
Slate roof protection - slate treatment
The disadvantages of asbestos cement include: reduced strength when saturated with water, fragility and warping when humidity changes, poor impact resistance.
What and how can slate be processed? so that it doesn’t turn green or black?
In order to get rid of these shortcomings, waterproof compounds are applied to the surface of asbestos-cement products, protecting the material from moisture and mechanical damage, ensuring good water drainage and not retaining dust.
To do this, the asbestos cement sheet is dried to 7...6% humidity, after which its surface is cleaned of dirt, primed and finally painted with weather- and water-resistant painting compounds.
By the way, to increase water resistance and reduce the release of asbestos dust, which causes specific diseases, back side products are also primed.
Painting of slate sheets with perchlorovinyl compounds (PVC, TsPKhV, KhV-161) is carried out at a temperature not higher than +4°C (due to the toxicity of the compounds) and not lower than -20°C.
To do this, first apply perchlorovinyl primer to the surface of the sheet, which dries in 2–3 hours in summer conditions.
The dried surface is painted with perchlorovinyl compounds using a spray gun (preferably brand SO-71A). When using a mechanized painting method, the composition must be systematically mixed in the paint injection tank to avoid stratification. During operation, the distance from the gun to the surface to be painted must be at least 0.5 m; the gun should be moved along the surface evenly, at a speed of about 0.3 m/s.
Slate is painted in stripes. The first stripe is applied from top to bottom, the second to the right of the first, but from bottom to top, the third, like the first, and so on. To obtain a continuous coating (without gaps), it is necessary that each subsequent strip overlaps the previously applied one by 3...4 cm. Typically, two layers of the composition are applied to the slate, and the second layer is sprayed only after the first has dried.
When painting twice with a PVC composition, per 100 m² of surface the following is consumed (kg):
PVC paint - 59;
PVC primer - 15;
Solvent (solvent; R-4; 5% PVC varnish) - 10.
When applying a ready-to-use cement-perchlorovinyl composition (CPVC) to 100 m² of surface, 41 kg of the composition is consumed for the first painting, and 36 kg for the second.
Slate surfaces are also treated with KO-174 enamel, which is a dispersed system (suspension) consisting of a solid phase (fillers) and a liquid phase (organosilicon varnish KO-85, diluted with a solvent - a mixture of butyl acetate, acetone, xylene and toluene).
As a result of the evaporation of the solvent, the enamel hardens. The drying time of the enamel at a temperature of 18...25°C is about 2 hours. The enamel has good adhesion, so it reliably sticks to asbestos cement sheets, and the enamel coating is characterized high strength and waterproof.
Thickened enamel is diluted with R-5 thinner. Before painting with enamel, the surface is prepared in the same way as before painting it with perchlorovinyl compounds. The slate must be dried before painting, since its humidity should not exceed 8%.
Apply enamel 2…3 times paint brush or paint sprayer. Each subsequent layer is applied 1…2 hours after the previous one. Please note that enamel is toxic, so it is used only for external use.
The slate is also covered with organo-silicate compounds. One of the most durable compounds is composition OS-12-03, which consists of the paint itself (a suspension of organosilicon polymers and inorganic additives in toluene) and a hardener - polybutyl titanate or butyl titanate.
Before use, add a hardener to the paint composition in an amount of 1% by weight of the paint and thoroughly mix the composition in the container for 1 hour using a nozzle with blades. The paint hardens as a result chemical reaction between components. Xylene or toluene is used as a solvent. The coating has good adhesion and adheres reliably to concrete, cement, sand-lime brick, ceramics and metal (with the exception of halogen-containing plastics).
For slate and metal roofs The organo-silicate composition is applied at temperatures from -40°C to +40°C, using a paint brush, roller or paint sprayer.
The composition dries quickly - in 30 minutes. “Viability” of the composition prepared for application is 24…48 hours. When applying a two-layer brush coating of asbestos-cement or concrete surfaces consume up to 400 g of composition per 1 m². Of course, the composition is applied to the surface, previously cleaned of dust and lubricating oils, by sprinkling with mortar.
When working with a paint sprayer, use a nozzle with a diameter of 1.8...2 mm and form a round torch from the paint.
During the application of paint, it is thoroughly mixed by hand.
Slate asbestos cement sheets are also painted with silicate paints prepared on the basis of potassium soluble glass (K2O mSiO2) with a density of 1.3...1.5 g/cm³. Silicate paints also contain a separately supplied mixture of pigments with chalk, taken in a 1:1 ratio (by weight).
The value m is the ratio of the number of silica molecules (SiO2) to the number of alkali oxide molecules (K2O) and is called the silicate module of glass. For potassium glass, m is 3…4. The higher the module, the higher the quality of liquid glass.
The density of glass depends on its concentration. Often liquid glass comes from the manufacturer with increased density, so it has to be diluted with water.
How to paint a slate roof: technology
The required amount of water is calculated by the formula:
U1=U2(p1-p2)/(p2-1000),
where U1 is the amount of water that needs to be added to the solution, l;
U2 - initial volume of liquid glass, l;
p1 and p2 - initial and required density of liquid glass according to the hydrometer, kg/m³.
There are 10 liters of liquid glass with a density of 1500 kg/m³. You need to get a solution with a density of 1370 kg/m³. It is required to determine the amount of water U1 that must be added to the solution. The amount of water added is:
U1=10*(1500-1370)/(1370-1000)=3.5 l.
Before use, strain the composition through a No. 0.25 mesh containing 694 holes/cm².
Silicate paints are made only with alkali-resistant pigments and they have fire-retardant properties. It is impossible to prepare the painting composition for future use, since after a day it becomes unsuitable for further use.
For silicate paints, it is allowed to use only potassium glass, since the presence of sodium glass (Na2O mSiO2) causes the appearance of a white coating, so-called efflorescence, on the painted surface.
Therefore, before using silicate paints, it is necessary to check their quality, that is, to determine whether they contain sodium soluble glass.
To do this, take a red clay brick, the five sides of which are painted twice with the paint tested twice. After the paint film has completely dried, the “experimental” brick is moistened with water until completely saturated and placed on the unpainted side. If the soluble glass contains an admixture of soda glass, then after 1...2 days it will appear on the painted surfaces of the brick. white coating and the paint will begin to “chalk” when rubbed with your hand.
Priming the slate surface before painting is carried out liquid glass density 1.41 g/cm³, while the consumption of liquid potassium glass is 27.3 kg per 100 m².
The first painting is carried out with a composition with a density of 1.14 g/cm³, the second - 1.18 g/cm³. The consumption of liquid potassium glass (per 100 m²) for the first painting is 14.8 kg, for the second - 11.1 kg. Let's not forget about the dry pigment mixture, which will require 30.9 kg for the first coloring, and 26.6 kg for the second.
Asbestos-cement slate sheets are painted in warm weather (at positive temperatures), avoiding painting in direct sunlight.
To impart water-repellent properties to the applied film, hydrophobic additives - organosilicon liquids (GKZh-10 and GKZh-11) - are introduced into the silicate compositions intended for the second painting. They do it like this. Diluted liquid potassium glass (density 1.15 g/cm³) is loaded into the mixer, then poured required amount pigments and mix the components until homogeneous, where GKZh-10 or GKZh-11 (commercial 30% concentration) is added.
Consumption of hydrophobic additives is 2.3 kg per amount of liquid potassium glass required to cover 100 m² of slate.
Of the anhydrous compositions for painting asbestos-cement slate sheets, the following brands of paints are used:
White lead thickly ground (MA-011; MA-011-N-1; MA-011-N-2),
Thickly ground zinc white (MA-011; MA-011B; MA-011N; MA-011NV),
Oil paints (MA-011 and MA-015; thickly rubbed special),
Thickly rubbed oil and alkyd colored paints (MA-011; MA-015; GF-013; PF-014),
Oil and alkyd paints ready for use (MA-11; MANN; MA-15; MA-15N; GF-13; GF-13N; PF-14; PF-14N; MA-21; MA-21N; MA-22; MA-22N; MA-25; MA-25N),
Thickly grated lead greens (MA-011-N-2; MA-011-N-3; MA-015-N-2; MA-015-N-3),
Oil and alkyd paints, earthen, thickly rubbed (red lead, mummy, ocher).
All types of primers and the above-mentioned waterless paint compositions for external coatings are prepared only on natural drying oil and diluted only with natural drying oil!
Coloring is carried out in the manner described above. Before coating asbestos-cement slate surfaces protective composition must be completed preparatory work After cleaning them from dust and soot, dry and prime the slate.
I repeat, it is not allowed to paint in dry and hot weather when exposed to direct sun rays, as well as during rain or on a damp surface, you should not work in strong winds.
The most favorable time of year for painting work asbestos cement roofing- spring months. Painting works are carried out using special ladders that evenly distribute the weight of a person over the surface of asbestos-cement slate surfaces, which eliminates their damage.
All materials from the “Repair and Construction” section
How to paint slate?
1.Characteristics of slate as a roofing covering
2. Slate roof repair
3. Cleaning the roof
4. Elimination of cracks and replacement of sheets
5. Painting slate
Roofing material such as slate is always popular, regardless of the appearance of new coatings on the market.
It is distinguished not only by its reliability, but also by its affordability. Slate painting is done in order to increase the service life of this roofing coating. Therefore, it is worth understanding how to paint slate and how to paint slate on the roof, as well as how to repair the roof. Detailed instructions With photos and videos of this process, if desired, you can easily find them on our website.
Characteristics of slate as a roof covering
This material, which was once made using clay shale, is one of the oldest materials of a kind. Of course, such natural slate slate is quite difficult to find today, partly due to the fact that it has an incredibly high price (read: “Installation of slate roofing - installation methods”).
However, an artificial version of such a coating - flat or corrugated asbestos-cement sheets - are very widespread today.
Nowadays, others are offered roofing materials, having some relation to slate, for example, Euro-slate, the basis of which is bitumen (read: “Euro-slate - reviews and main characteristics”), metal slate, etc.
But asbestos-cement slate is still the most popular roofing type.
The main advantages of slate:
- a do-it-yourself slate roof is easy to make;
- low level of thermal conductivity;
- resistance to low temperatures and atmospheric phenomena;
- affordability;
- Fire safety.
Slate roofing is, by definition, durable.
This is especially true for roofs where painted slate is used, since protective film, created by paint for slate, helps to increase the resistance of slate to various mechanical and natural influences, therefore, the service life of the roof is extended.
In addition, slate is a completely repairable material. So, if any cracks or defects appear on the slate sheets, then there is absolutely no need to redo the entire roof, even if a significant part of the material is completely destroyed.
It will only be enough to replace the damaged sheets, taking into account the size of the slate that was previously used.
What and how to paint flat slate? Overview of market offers + step-by-step instructions
In the case when painted slate is used, there is absolutely no danger to health, since thanks to paint it not only increases the reliability of the roof, but also stops the emission of dust, which contains asbestos particles.
Slate roof repair
No matter how mobile and easy to repair slate is, if any defects appear, repairs still need to be done, and the sooner the better.
Usually renovation work consist of three stages:
- roof cleaning;
- elimination of cracks or, if necessary, replacement of sheets;
- painting slate.
Carrying out repairs slate roof with your own hands, strictly following the rules of all three stages, will allow the roof to last for decades.
Roof cleaning
Usually, if the roofing material is painted slate, then cleaning the roof will not present any difficulty; you will only need to sweep away all the debris that has accumulated on it.
If the slate sheets are not painted, this can lead to the appearance of moss and lichen on them, which, of course, cannot have a positive effect on both the appearance of the roof and its performance properties.
One of the tools used to clean the roof is a brush equipped with metal bristles. The work can be simplified by using a drill with an attachment similar to a wire brush.
Slate can also be cleaned well plain water which is supplied under pressure.
Compact portable car washes used for cars are perfect here.
Repairing cracks and replacing sheets
The basis for repairing relatively small cracks in slate can be mastic, the base of which is bitumen or a special putty made using chalk and drying oil.
A special composition for repairing cracks may also consist of the following elements:
- 2 cement parts;
- 3 asbestos parts;
- PVA glue diluted in a ratio of 1/1 with water or undiluted water-based paint, frost-resistant.
Liquid elements must be selected in such a volume that the final composition has the consistency of a thick paste.
Due to rapid hardening, these compositions need to be prepared in small portions.
Another option for sealing wide cracks is to glue patches made of fabric onto them.
In this case, the desired place is primed, and then a patch is applied to a thick layer of paint, the size of which should be larger size cracks of 10 centimeters. Next, the patch needs to be covered with an additional layer of paint.
This same stage of repair also includes the replacement of damaged slate sheets. To do this, special walkways are mounted on both sides of such a sheet, for which ridge brackets serve as fastenings. To move on the roof during repairs, in this case a wide board is placed across these walkways, on which you can walk if necessary.
Nails and screws on the necessary sheets you need to either completely remove them or loosen them. If nails are being removed with a nail puller, it is important to place a piece of wood underneath the tool.
The required sheet, that is, the one that needs to be replaced, needs to be lifted and a new one placed in its place. It should be located along the edge of the ceiling and move towards the ridge. The new installed sheet is secured with screws or nails.
Slate painting
All professionals agree that painting slate is not only possible, but necessary, as this significantly improves the properties of the roof and extends its service life.
An important factor is aesthetic appearance painted roof.
Therefore, painting slate with your own hands can be done, more difficult question will be something to paint flat slate. Previously, the standard was used for this Oil paint, despite all the negative nuances of this method (fragility, tendency to rapid destruction).
Nowadays, special paint and varnish compositions, which are suitable for painting not only slate, but also tiles, concrete, etc. The basis of such paints is acrylic, thanks to which these compositions are resistant to low temperatures, solar radiation and precipitation.
This, of course, has a positive effect on the aesthetic appearance of the roof, which will remain so for a long time.
When deciding what to paint slate with, you can choose a special paint for slate, called triora. It is resistant to external influences, in addition, it can be used for both slate and tiles, and even to cover ground floor structures.
There are other paints manufactured as domestic producers, and foreign (read: “How to paint a slate roof: technology”).
Painting slate yourself, that is, without the participation of professionals, is quite possible. Of course, the best option will paint the slate sheets before laying them, but during repairs this will not be possible, so you will need to apply paint to already laid sheets.
3 stages of slate painting:
- primer is applied;
- the main coating is applied;
- The final coating is applied.
The painting tool can be a spray gun or a paint brush.
Flat slate can also be painted using a roller; the size of the flat slate allows this.
Before applying primer to the slate, it is best to properly treat the coating with an antiseptic solution, which is most often sold in concentrated form and is diluted with water before use.
Using such a solution will prevent fungus or lichen from appearing on the slate. It can be applied either with a wide brush or with any device capable of spraying liquid. It is also important to remember protective equipment- glasses, gloves, respirator.
A slate primer, which often contains acrylic, can then be applied. liquid formulations, capable of penetrating deeply into the pores of the coating, thereby giving it greater reliability and better adhesion of the slate to the paint.
Painting slate on the roof, watch the video:
Very often, primer from one or another manufacturer is offered along with paint, so it would be better to opt for the same brand. Apply primer in the same way as paint: you can do it with a sprayer or a roller.
Due to the fact that slate is a porous material, painting it without a primer will be uneven, which will certainly lead to excessive paint consumption.
After the primer has dried, you can begin to apply the main coat of paint. It is very important to apply it well to all corners and ends of the coating.
The final coating is designed to give slate roofing a beautiful appearance.
It helps to make the surface uniform and uniform, without visual transitions and paint streaks. This layer can be applied only after the base layer has dried.
The paint used for the final coating is the same as for the main one, the only difference is in its smaller quantity.
The last stage requires approximately one third of the total paint volume, and the base coat - two thirds.
So, it is quite possible to paint slate yourself. This will give great opportunity save money significant part finance, as services professional craftsmen usually not very cheap.
How and with what to paint a slate roof
More recently, slate was so popular that two-thirds of buildings in our country were covered with it. Currently, in conditions of constant competition, each manufacturer is trying to improve the quality and diversify the roofing materials they produce. Despite this, slate is still in demand, and all thanks to it positive aspects, which have remained unchanged over time. This is a low price, good water and frost resistance, and a long service life. But these qualities are not always the main ones when choosing a material for the roof, especially considering that over time slate acquires a gray-green color, especially on the north side, which is often covered with moss. And just new factory slate will not add any zest to the new home.
IN Lately use such types of slate as profiled sheets, flat slabs and roofing panels.
If you still choose slate, there is one option that will help decorate the appearance of the house, namely painting the slate.
Preparing slate for painting
To paint slate you need to prepare following materials and tools:
- metal brush;
- drill;
- Bulgarian;
- jet washer high pressure;
- construction antiseptic;
- brush;
- spray;
- respirator;
- glasses;
- gloves;
- acrylic or enamel paint;
- primer.
Before you start painting, you need to clean the slate. especially if it has been in use for several years.
A slate roof can be cleaned in a variety of ways.
A regular metal brush is suitable for cleaning slate, but it is better to use a steam unit.
The first is to clean it yourself using a regular metal brush. This method is the most labor-intensive and requires large quantity time, efficiency and quality leave much to be desired. The main requirement when performing this work is that the roof is not wet.
The second method is to clean the roof using a special attachment on a drill or grinder. Cleaning the roof in this way has only one advantage - it is quality due to the use of power tools. This does not reduce the cleaning speed.
The third method is the most effective, and most importantly, it allows you not to stop working due to weather conditions. Its essence lies in the fact that slate is cleaned with water under high pressure. In order to clean the roof this way, you will need a specialized washer to create a high-pressure jet. The optimal pressure for such a process should not exceed 250 atmospheres. This is due to the fact that an increase in pressure above the norm can damage the slate itself, and a jet with low pressure levels will not allow the surface to be properly cleaned.
The undoubted advantage of this method is that it will take only 1-2 days to clean a roof with an area of 100 m2.
Treatment of slate before painting
The next step in preparing slate for painting on your own is treating it with an antiseptic followed by hydrophobization.
As you know, fungal spores multiply in a damp environment, so the slate needs to be treated with a product to increase water repellency.
The result of cleaning the slate: not a trace of debris, mold or fungi remained.
It is also important that old slate has increased porosity and is therefore susceptible to premature destruction in conditions high humidity. Hydrophobization is used to prevent this and to increase the service life of slate.
To give the treated roof an aesthetic appearance, they resort to painting it. Of course, in ideal painting the roof (slate) is carried out immediately before starting roofing works. But, as a rule, it is after several years that the owners only begin to think about what to do with the terrible roof and how to paint the slate that is already lying there. In turn, the stage of painting the roof is the most important and final.
Sometimes the average person may wonder whether slate can be painted. The answer is simple: not only is it possible, but it is also necessary. Paint is an additional protective layer, which will strengthen the slate structure from destruction. Painted slate is less susceptible to severe frost.
Choosing paint for slate
Paint on slate is easily applied with a regular brush.
Correctly chosen paint is the key to not only the beauty of the future roof, but also high-quality protection. Nowadays, slate paints are presented in acrylic and enamel samples.
Experts recommend using these types of paints for painting, since they are designed to close all microcracks on the slate, and the film formed as a result of painting will cope perfectly with atmospheric phenomena. These paints contain binding components, making them ideal for painting flat slate. In the case where the roof is used in extreme weather conditions, with different temperatures environment, it is best to use quick-drying enamels.
And yet, when you need to choose what to paint slate with, it is recommended to turn to specialists. They will always help you choose suitable paint taking into account the actual condition of the roof.
The quality of painting is influenced not only by correctly selected paint, but also by the technology of the application process itself. Basically this process can be broken down into three stages:
Instead of a brush, you can use a special paint sprayer - this will significantly speed up the process of updating the roof.
- Coating the slate surface with a primer.
- Painting the slate with the first coat of paint.
- Applying the second (finishing) coat of paint.
For priming it is better to use compounds with deep penetration, which will provide significant strengthening of the slate surface. It is much easier to paint a pre-primed roof, since, thanks to the primer, the paint will apply more evenly, and its consumption will be significantly less than without pre-treatment. The recommended primer consumption is 100-150 g per slate sheet. It is best to apply the primer with a sprayer, at an air temperature ranging from +5 to +30 degrees. Complete drying time is about 12 hours. After this time has passed, you can only begin to paint. It is not recommended to work with soil solutions with unprotected hands; you should avoid getting them in your eyes. Properly preparing the slate surface before painting is the guarantee that the paint will last for many years and will not have to be repainted.
After applying the primer, you need to let the roof dry for a day, and the next day you can start painting it.
Slate painting technology
When starting to paint slate with the first layer, you need to take into account the fact that it is the main one and 2/3 of all paint and varnish materials. The slate sheet painted with the first layer should not have gaps; do not forget about the ends and corners. It is necessary to pay due attention to places that are most difficult to reach. Already after applying the first layer of paint, the roof is given an unrecognizable appearance, but you still shouldn’t stop there. The next layer is no less important.
Start painting finishing layer This is possible after the slate painted with the first layer has completely dried. Applying paint a second time will give the already painted roof a uniform color and get rid of streaks. As a rule, 1/3 of all paint is spent on this layer.
Painting slate by hand is not so much a long process as a labor-intensive process that requires certain skills.
The technology described above can be safely used for painting both wavy and flat slate. Thanks to this simple technology, roofs are given an aesthetic appeal that will decorate any building. And, of course, painting slate will increase its service life under environmental conditions.
http://kryshikrovli.ru
Asbestos slate is gradually losing its position in the market building materials. The reason is its nondescript appearance. In this article we will consider the topic - how to paint a slate roof, what paint to use to make this roofing material presentable. Topics will be covered regarding the benefits of painted slate roofing, as well as the types of paints that are used today to paint roofing structures covered with slate.
Why should you paint slate roofs?
The first reason is indicated - plainness. Keep up with the slate in terms of design design for ondulin, corrugated sheets, metal tiles and others roofing coverings difficult. There is only one way out - to cover it with paint. This will not affect the cost of the roofing structure, because slate is the cheapest material. Having painted it, we cannot talk about high costs for paint per 1 m2.
In addition, the paint and varnish materials that are used to paint slate roofs today are not in short supply, their variety is quite wide, so there will be no problems with the choice. The dyeing process itself is simple. One worker is enough for a team of craftsmen to paint the roof of a large house.
The second reason is protective. Slate is a porous material. Over time, microcracks form on its surface. What this entails is probably not worth explaining. But we need to pay attention to this point. In winter, water penetrates into cracks where it freezes. Ice simply breaks the asbestos fibers, thus reducing the strength of the material itself.
The same applies to the process when mosses and lichens grow on slate. With their roots, they penetrate deeply into the body of the slate, widening and deepening the cracks.
Therefore, painting is a protective layer that will not only become a barrier to water, but also an insurmountable barrier for plants. The film formed on slate from dried paint is very durable. In any case, she will be able to cope with the loads described above for several years. This means that a roof covered with slate will last longer.
The third reason is the harmfulness of asbestos. Several decades ago, propaganda against slate began in the West. It also moved to Russia, and was supported by manufacturers of more expensive building materials. Although it has long been proven that this is just propaganda to give other roofing materials the opportunity to be present and sold on the market. But if this aspect haunts you, then with the help of paint you will solve this problem.
So, let’s summarize why painted slate is better than unpainted slate:
Increase decorativeness roofing structure.
Using a certain type of paint, you can give slate matte or gloss.
Make a surface smooth without pores or cracks.
Don't give it a chance to grow mosses and lichens.
Install protection from the appearance of asbestos dust.
Increase lifetime. Painted material will last 1.5 times longer.
Types of paints for slate
A roof, even one covered with paint, requires special treatment. It is subject to all known natural stresses, so the choice of paint must be approached with special care. That is, it must withstand sunlight, changes in humidity and temperature, and mechanical stress. At the same time, it should adhere well to asbestos-cement slate.
That is, you cannot paint slate with whatever paint comes to hand first. Here is a list of suitable colors:
acrylic;
silicone;
alkyd;
enamels called "Liquid Plastic".
Let's look at each variety separately and determine their technical characteristics, as well as their pros and cons.
Acrylic paints
This is the most extensive line of paint and varnish products with intense color and varying degrees of gloss (from highly glossy to highly matte). This category of coatings is divided into two groups:
on water based , they are also water-dispersed;
based organic solvents.
Group No. 1
Composition: latexes, also known as acrylic copolymers, pure water, pigments and various additives that improve the quality of paint (antifreeze, biocides, etc.). It should be noted that the percentage of water in the paint is no more than 15%. It functions as a diluent and solvent.
Here are the advantages of acrylic water dispersion material:
This environmentally friendly material , which under the influence of natural loads does not emit harmful substances into the atmosphere;
high adhesion to any building materials, including slate;
high hiding power, within 200-300 ml/m2;
ease of application;
sustainability to precipitation;
This non-toxic material;
high fire resistance, because the base is water;
not necessary add chemical solvents;
dries within 1-2 hours;
paint layer increases frost resistance slate;
increases waterproofing properties roofing material;
service life – 5 years.
In the group of water-dispersed acrylic paints There is a subgroup called “rubber”. These are all the same components, only the structure of the material is thick mastic. It is applied to the roof in a thin layer, which, after drying, forms an elastic flexible film, very similar to rubber. Hence, in principle, the name.
On our website you can get acquainted with the most . In the filters you can set the desired direction, the presence of gas, water, electricity and other communications.
The film is not only elastic, but also very durable. At the same time, it covers cracks up to 1 mm wide well, preventing them from expanding later. Mastic has high adhesion to porous surfaces. And she is one hundred percent waterproofing coating. It is represented on the market in a fairly wide range. It is available in cans and buckets labeled “Rubber Paint.”
Group No. 2
Acrylic paint for this type of slate roof is not diluted with water. For this purpose, solvents of organic origin are used, most often white spirit is used. There are also matte and glossy paints, which differ from each other in the amount added to the composition. acrylic resin. The higher its percentage, the higher the gloss of the material.
How does this variety differ from water-dispersed:
colorful film applied to slate stronger;
higher water-repellent characteristics;
increased elasticity coatings;
for a long time holds original color.
The disadvantages include a pungent odor that gradually disappears, a slightly higher consumption - 250-350 ml/m2, drying time is longer - within 10-24 hours. Here you can add not the widest range presented on the modern market.
Silicone paints
Silicone paints consist of pigments and silicone binders, which give the paint and varnish material special strength and elasticity. Therefore, silicone-based paints are rightfully considered reliable and durable coatings, and not only for slate. Only they can close cracks up to 2 mm wide.
So, what are the advantages of this type of paintwork:
increased strength applied layer;
maximum possible elasticity;
added to the paint supplements, which prevent the formation of colonies of harmful microorganisms on roofs;
high waterproofing quality;
high dirt-resistant properties;
silicone paints can be applied to the slate of the latter;
high fire safety;
This non-toxic material;
life time within 10-15 years.
The only negative that should be noted is the high price compared to other types.
On our website you can find contacts construction companies, which offer construction services for small architectural forms. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.
Alkyd paints
Composition: alkyd resin, pigments and organic solvent. It should be immediately noted that this type of paint and varnish product belongs to the category of quick-drying ones. After 30-90 minutes the paint dries completely. The applied layer is quite elastic. No cracks form on it throughout its entire service life. And the term is not the longest - only 5 years. Although this is a normal indicator for a roof.
To the advantages of alkyd paints we add high moisture resistance, good adhesion, and ease of application. Using them, there is no need to coat the slate roof with primers. And one more important advantage that many masters have highlighted is the ability to tint alkyd paint white.
Video description
The video shows the process of painting slate:
Polymer paints
“Liquid plastic” got its name for a reason. It consists of suspensions of various polymers. This can be PVC (polyvinyl chloride), polystyrene or polyurethane. Each of them is the main paint and varnish product. This also includes pigments, additives that improve the quality of paint, and solvent. It turns out that after applying the paint layer, the solvent evaporates from it, and the polymer dries and hardens, forming on the slate roof thin layer plastic. In this case, the surface may be either glossy or matte.
Advantages of this material:
absolute moisture resistance;
dries out within half an hour;
one hundred percent environmental friendliness;
material inert to chemistry;
plastic - material incombustible;
paint can be applied without preliminary priming;
doesn't lose its design qualities under the influence of sunlight, precipitation and wind;
highest frost resistance, you can apply paint to slate even at a temperature of -10C;
life time– 10-15 years.
So, we examined those types of paint and varnish products that answer the question posed by the topic of the article - how to paint slate on the roof. Now let's move on to the section on how to properly paint a slate roof.
Slate painting technology
It should be immediately noted that even the most expensive and quality paint, chosen for the design of slate laid on the roof, does not guarantee that the applied coating will withstand its service life. The most important point is a competently carried out painting process. It is divided into several stages, the sequence of which must be strictly observed.
Stage No. 1
First of all, the slate laid on the roof must be prepared. That is, the slate roof is being cleaned. This is done in three ways:
Mechanical. To do this, use scrapers, brooms, brooms, brushes and other identical hand tools and devices. With their help, dust, dirt, debris, and small vegetation are removed from the slate surface.
Hydraulic. To do this, use a stream of water under high pressure. You will need a long hose, a nozzle, a pump and a container of water (you can connect the pump to the water supply).
Combined. They combine the two previous methods, which is more effective, especially when old slate coverings are prepared for painting.
Stage No. 2
At this stage, the roofing material is primed. Usually it is selected according to technical specifications paints. It is better if the primer and paint are from the same manufacturer. As mentioned above, some slate paints can be installed without prior priming.
If a primer is necessary, it is applied to the slate with brushes, rollers or a spray gun. The latter option is simpler and more convenient to apply, and also more economical. It is better to apply the primer in two layers, ensuring that the first one dries well before applying the second.
Stage No. 3
This process is no different from priming. It is carried out with the same tools. The material is applied in two layers, the first must be dried before applying the second. The first layer is considered the base layer. With its help, all irregularities and defects in the roofing material are covered. Therefore, it is very important to paint the joints, corners, slate ends, as well as ridge and gable elements.
The second layer is already the finishing (painting) layer. It is with its help that the color design of the roofing structure is created. It is this layer that creates a bright, uniform color; there should be no streaks or smudges left on it.
Video description
The video shows how easy it is to paint slate on a roof with a brush:
Conclusion on the topic
So, we looked at the topic - how to paint old slate on a roof, and how to do it correctly. As you can see, the paints that can be used to paint slate roof structure, a lot. Each has its own pros and cons, but they all have one quality - they tolerate natural stress well. This means that slate roofs painted with these paints will delight you for many years.
Asbestos-cement slate roofs have been used in construction for decades, and slate is the most common roofing material in Russia. Asbestos cement is an artificial stone material obtained by hardening an aqueous mixture of Portland cement and finely fluffed chrysotile asbestos fibers that reinforce the cement component. Asbestos-cement products have high mechanical strength in bending, low density, low thermal conductivity and water permeability, high frost resistance, resistance to alkalis, and are also characterized by sufficient biostability. Tensile strength of asbestos-cement slate sheet: in tension - 20...25 MPa, in bending - 27...42 MPa, in compression - 45 MPa or more. The recommended roof slope is 14...60°. Lifetime asbestos cement roofs is 30...40 years. The sheets are easy to drill and saw.
Slate roof protection - slate treatment
The disadvantages of asbestos cement include: reduced strength when saturated with water, fragility and warping when humidity changes, poor impact resistance.
What and how can slate be processed? so that it doesn’t turn green or black?
In order to get rid of these shortcomings, waterproof compounds are applied to the surface of asbestos-cement products, protecting the material from moisture and mechanical damage, ensuring good water drainage and not retaining dust. To do this, the asbestos cement sheet is dried to 7...6% humidity, after which its surface is cleaned of dirt, primed and finally painted with weather- and water-resistant painting compounds. By the way, to increase water resistance and reduce the release of asbestos dust, which causes specific diseases, the back side of the product is also primed.
Painting of slate sheets with perchlorovinyl compounds (PVC, TsPKhV, KhV-161) is carried out at a temperature not higher than +4°C (due to the toxicity of the compounds) and not lower than -20°C. To do this, first apply perchlorovinyl primer to the surface of the sheet, which dries in 2...3 hours in summer conditions. The dried surface is painted with perchlorovinyl compounds using a paint spray gun (preferably brand SO-71A). When using a mechanized painting method, the composition must be systematically mixed in the paint injection tank to avoid stratification. During operation, the distance from the gun to the surface to be painted must be at least 0.5 m; the gun should be moved along the surface evenly, at a speed of about 0.3 m/s. Slate is painted in stripes. The first stripe is applied from top to bottom, the second to the right of the first, but from bottom to top, the third, like the first, and so on. To obtain a continuous coating (without gaps), it is necessary that each subsequent strip overlaps the previously applied one by 3...4 cm. Typically, two layers of the composition are applied to the slate, and the second layer is sprayed only after the first has dried.
When painting twice with a PVC composition, per 100 m² of surface the following is consumed (kg):
PVC paint - 59;
PVC primer - 15;
Solvent (solvent; R-4; 5% PVC varnish) - 10.
When applying a ready-to-use cement-perchlorovinyl composition (CPVC) to 100 m² of surface, 41 kg of the composition is consumed for the first painting, and 36 kg for the second.
Slate surfaces are also treated with KO-174 enamel, which is a dispersed system (suspension) consisting of a solid phase (fillers) and a liquid phase (organosilicon varnish KO-85, diluted with a solvent - a mixture of butyl acetate, acetone, xylene and toluene). As a result of the evaporation of the solvent, the enamel hardens. The drying time of the enamel at a temperature of 18...25°C is about 2 hours. The enamel has good adhesion, so it reliably sticks to asbestos-cement sheets, and the enamel coating is characterized by high strength and water resistance. Thickened enamel is diluted with R-5 thinner. Before painting with enamel, the surface is prepared in the same way as before painting it with perchlorovinyl compounds. The slate must be dried before painting, since its humidity should not exceed 8%. Apply the enamel 2...3 times with a paint brush or paint sprayer. Each subsequent layer is applied 1...2 hours after the previous one. Please note that enamel is toxic, so it is used only for external use.
More recently, slate was so popular that two-thirds of buildings in our country were covered with it. Currently, in conditions of constant competition, each manufacturer is trying to improve the quality and diversify the roofing materials they produce. Despite this, slate is still in demand, and all thanks to its positive aspects, which have remained unchanged over time. This is a low price, good water and frost resistance, and a long service life. But these qualities are not always the main ones when choosing a material for the roof, especially considering that over time slate acquires a gray-green color, especially on the north side, which is often covered with moss. And just new factory slate will not add any zest to the new home.
Recently, such types of slate have been used as profiled sheets, flat slabs and roofing panels.
If you still choose slate, there is one option that will help decorate the appearance of the house, namely painting the slate.
Preparing slate for painting
To paint slate, you need to prepare the following materials and tools:
- metal brush;
- drill;
- Bulgarian;
- high pressure jet washer;
- construction antiseptic;
- brush;
- spray;
- respirator;
- glasses;
- gloves;
- acrylic or enamel paint;
- primer.
Before you start painting, you need to do this, especially if it has been in use for several years.
Can be cleaned in various ways.
A regular metal brush is suitable for cleaning slate, but it is better to use a steam unit.
The first is to clean it yourself using a regular metal brush. This method is the most labor-intensive and time-consuming, but the efficiency and quality leave much to be desired. The main requirement when performing this work is that the roof is not wet.
The second method is to clean the roof using a special attachment on a drill or grinder. Cleaning the roof in this way has only one advantage - it is quality due to the use of power tools. This does not reduce the cleaning speed.
The third method is the most effective, and most importantly, it allows you not to stop working due to weather conditions. Its essence lies in the fact that slate is cleaned with water under high pressure. In order to clean the roof this way, you will need a specialized washer to create a high-pressure jet. The optimal pressure for such a process should not exceed 250 atmospheres. This is due to the fact that an increase in pressure above the norm can damage the slate itself, and a jet with low pressure levels will not allow the surface to be properly cleaned.
The undoubted advantage of this method is that it will take only 1-2 days to clean a roof with an area of 100 m2.
Treatment of slate before painting
The next step in preparing slate for painting on your own is its subsequent hydrophobization.
As you know, fungal spores multiply in a damp environment, so the slate needs to be treated with a product to increase water repellency.
The result of cleaning the slate: not a trace of debris, mold or fungi remained.
It is also important that old slate has increased porosity and is therefore susceptible to premature destruction in conditions of high humidity. Hydrophobization is used to prevent this and to increase the service life of slate.
To give the treated roof an aesthetic appearance, they resort to painting it. Of course, ideally, painting the roof (slate) is carried out immediately before the start of roofing work. But, as a rule, it is after several years that the owners only begin to think about what to do with the terrible roof and how to paint the slate that is already lying there. In turn, the stage is the most important and final.
Sometimes the average person may wonder whether slate can be painted. The answer is simple: not only is it possible, but it is also necessary. Paint is an additional protective layer that will strengthen the slate structure from destruction. Painted slate is less susceptible to severe frost.
Choosing paint for slate
Paint on slate is easily applied with a regular brush.
Correctly chosen paint is the key to not only the beauty of the future roof, but also high-quality protection. Nowadays, slate paints are presented in acrylic and enamel samples.
Experts recommend using these types of paints for painting, since they are designed to close all microcracks on the slate, and the film formed as a result of painting will cope perfectly with atmospheric phenomena. These paints contain binding components, which make them ideal for painting. In cases where the roof is used in extreme weather conditions, with different ambient temperatures, it is best to use quick-drying enamels.
And yet, when you need to choose what to paint slate with, it is recommended to turn to specialists. They will always help you choose the right paint, taking into account the actual condition of the roof.
The quality of painting is influenced not only by correctly selected paint, but also by the technology of the application process itself. Basically this process can be broken down into three stages:
Instead of a brush, you can use a special paint sprayer - this will significantly speed up the process of updating the roof.
- Coating the slate surface with a primer.
- Painting the slate with the first coat of paint.
- Applying the second (finishing) coat of paint.
For priming, it is better to use compounds with deep penetration, which will ensure significant strengthening of the slate surface. It is much easier to paint a pre-primed roof, since, thanks to the primer, the paint will apply more evenly, and its consumption will be significantly less than without pre-treatment. The recommended primer consumption is 100-150 g per . It is best to apply the primer with a sprayer, at an air temperature ranging from +5 to +30 degrees. Complete drying time is about 12 hours. After this time has passed, you can only begin to paint. It is not recommended to work with soil solutions with unprotected hands; you should avoid getting them in your eyes. Properly preparing the slate surface before painting is the guarantee that the paint will last for many years and will not have to be repainted.
After applying the primer, you need to let the roof dry for a day, and the next day you can start painting it.
Slate painting technology
When starting to paint slate with the first layer, you need to take into account the fact that it is the main one and 2/3 of all paints and varnishes are consumed on it. The slate sheet painted with the first layer should not have gaps; do not forget about the ends and corners. It is necessary to pay due attention to places that are most difficult to reach. Already after applying the first layer of paint, the roof is given an unrecognizable appearance, but you still shouldn’t stop there. The next layer is no less important.
You can start painting the finishing layer after the slate painted with the first layer has completely dried. Applying paint a second time will give the already painted roof a uniform color and get rid of streaks. As a rule, 1/3 of all paint is spent on this layer.
Painting slate by hand is not so much a long process as a labor-intensive process that requires certain skills.
The technology described above can be safely used for painting both wavy and flat slate. Thanks to this simple technology, roofs are given an aesthetic appeal that will decorate any building. And, of course, painting slate will increase its service life under environmental conditions.