How to color slate: make a choice

Gusevsky Andrey Anatolyevich

How to paint slate

How can I color the slate? Slate is one of the most popular materials for roofing. If “ordinary” slate is suitable for a simple canopy, then to give additional aesthetics to a private house, it is better to use this material in colored form. What paint is preferable to use for slate and why, the article will tell.

Slate Features

Slate is sheets of asbestos cement, with a wave-like or flat profile made of asbestos-cement chips.

The advantages of slate are:

• High water resistance. Such material on the roof practically does not respond to the effects of precipitation.
• Low thermal conductivity.
• Good frost resistance. A roof made of slate does not crack even in severe frosts.
• Relatively easy to install.
• Material does not burn.
• Durability.
• High resistance to temperature changes.
• Just being processed.
• When the slate roof is covered with an attic roof, it does not particularly overheat and absorbs sounds well.

Like any roofing material, slate has some disadvantages:

• The surface of the slate is quickly covered with dust from asbestos chips, harmful to humans when inhaled.
• Often on the roof, on the north side, you can meet moss, which gives the roof a "green" look.
• Not too attractive appearance of the finished roof due to the gray color of asbestos chips, as part of the raw material for slate.
• A disadvantage can be considered not too long resistance to liquid, due to constant humidity, the surface may swell, and then crumble.

Tip: With proper selection of paint for slate, you can hide small flaws, and some can be completely removed. In this case, the coating plays a decorative and protective function: strength, hydrophobicity of the roof increase, asbestos dust is removed.

What paint is not suitable for finishing slate

The most unpleasant result, which is possible after an incorrectly selected paint for finishing slate, is a peeling roof in a year. For slate, you can not take ordinary facade paint or for exterior work.

This is due to the fact that:

• Asbestos fibers have a special structure, and a coating not intended for them can slip into layers after a year.
• The roof of the house is the most open element, which is affected by scorching sunlight, hail and wind with small debris, it can heat up most of all. Facade paint is not designed for such specific conditions.
• Absolutely not suitable for painting slate and simple enamel. Over time, it will not only begin to exfoliate, but will also hang with whole rags, which will give the roof a rather miserable appearance.
• The quality of the paint is affected by its coloring (see How to paint: choose an option) This is due to the acquisition of paint from one manufacturer, made on the same basis, and the solution used for coloring - with other properties, and besides, improper mixing of the compositions. On a slate, such a coating will not last long.

Tip: You should not experiment with compounds that do not combine with each other.

• The reason for the paint peeled off on the slate can be snow on the roof: after it is thawed during the day and at night with frost, an ice crust will appear, which peels off the color, which requires a smooth and even slippery coating on the slate.

Tip: This moment is very important for the rafter system: the less snow will linger on the roof, the lower the variable load on the rafters, which will increase the life of the roof.

• A new slate is recommended to withstand at least a year before painting.

What colors are best for slate

How to paint a flat slate

For slate painting, special impregnation paints are used, which additionally protect such surfaces from biodeterioration.

It could be:

• Moss.
• Fungus.
• Mold.

Types of paints for slate roofs can be:

• Polyurethane. They are on the slate after drying:

1. create a three-dimensional structure that protects the material from direct contact with the environment;
2. well withstand frequent and sudden changes in temperature;
3. have a high coefficient of elasticity.

The maximum protection of flat slate is obtained after coating it with modern solvent-based paints. They penetrate into asbestos fibers three times deeper than water-based paints, which allows the coating to serve for more than 20 years.

In order to lower the price of painting flat slate, you can take a paint-concentrate, bred several times. However, the paint itself should be diluted slightly less than indicated by the instructions.

• Acrylic. These are water-dispersion coatings giving the slate high hydrophobicity. In this case, raindrops slide freely from almost even roofs and snow quickly slides. This contributes to the fact that the water is very briefly located on the surface of the slate, which reduces the risk of leaks.

Such paints for slate fill even completely invisible cracks, small pores and bumps in the material.

Tip: To paint a flat slate with acrylic paint, you need to wait for good weather with an air temperature of (+ 5 ° C) to (+ 35 ° C), thoroughly clean the sheets from dirt, dry and dry for about two hours.

• Silicone. These are water-repellent paints, but when used on the windy side of the roof, the coating can burn out almost to gray in 10-20 years.
• Acrylic silicone. This is a new type of coating that combines the best properties of acrylic and silicone paints.
• Liquid rubber. This is the perfect coating for slate. The special materials included in its composition create a very dense protective film on the surface, which has good elasticity and has great durability. It does not stratify over time, even in areas with a harsh climate. And the presence of special pigments in the paint does not allow the color to quickly fade.

A serious drawback of rubber paints is their high toxicity, which requires performing work outdoors so that there are no strangers nearby and it is necessary to protect hands and respiratory organs.

• Liquid plastic - A completely new quick-drying coating.

Liquid plastic

In its composition, it is a suspension of fillers and pigments contained in the composition of copolymers of vinyl chloride and elastomers.

The main properties of the material are presented in the table:

Slate Painting Technology

Slate roof painting

High-quality painting of any slate should be carried out after preparation for work and correctly selected technology.

It includes:

• Surface cleaning. To do this, you need a synthetic brush, to clean the old roof, you will need a metal one to remove the existing moss and lichen.

Tip: A hard coat will remove the top layer of slate, which should be covered with a deep penetration of acrylic primer. Otherwise, no paint will be held, even the most expensive.

• External inspection of the roof for cracks. Before painting, the surface must be thoroughly cleaned, and it is better to repair:

1. with a small crack (just like a thread), you don’t need to do anything: two layers of paint will flow into it and it will disappear;
2. on a wider crack, you will need to make a patch.In this case: fiberglass is taken, you can burlap with tarpaulin, the material is soaked with thick paint for external work, the crack itself is smeared and the patch is shut up. The repaired area dries well and stains again.

• Surface treatment with antifungal drugs, which significantly increases the service life of the roof from slate.
• Primer (see Types of construction primers and their scope) Flat slate is primed with special formulations recommended by paint manufacturers. This will ensure reliable contact between the surface of the slate and the paint. By skipping this stage, you can create the prerequisites for peeling the coating.

Tip: When preparing slate for painting, you should always dilute the primer with clean water 30% more than the volume indicated in the instructions in order to get a good film permeability. Otherwise, the paint will lose its original appearance after 5 years.

When using expensive foreign paint, a preliminary primer is not necessary.

Surface painting. Work order:

• the paint mixes well to obtain a uniform coating. If the composition began to thicken, it must be diluted with a small amount of white spirit or bit acetate;
• the slate is painted horizontally, as in the photo. In this case, the paint can evenly fill in all the roughness and roughness, which cannot be achieved in an upright position.

Roof painting

When coated in two layers, for about one square meter of flat slate it will take about 150 grams of paint. The most durable coating will be obtained when painting slate with two layers of paint with a break between sets of one hour.

It is easier to paint slate on the ground, on a flat and horizontal surface. But when you lift it to the roof, the sheet can easily be scratched.

Tip: When painting slate, the first coat of paint should be applied on the ground with a brush or roller, and the second on the roof with a spray gun.

How to prepare a flat slate for painting than to paint, the video shows the features of the work in this article.