Wall priming: preparing for painting and wallpapering

Recommendation points

• What is a primer and why is it needed
• Which primer to choose
• Acrylic primers
• Latex primers
• Primers for wood and metal
• How to calculate the amount of primer
• Preparing walls for priming
• Work technology
• How to make a primer yourself

Before wallpapering or painting, the walls should be primed. This ensures that the topcoat adheres firmly to the surface. This cannot be neglected, otherwise in a couple of years the wallpaper will begin to lag behind the walls, and the paint will peel off. Let’s talk about how to choose a primer and apply it correctly.

What is a primer and why is it needed

The primer is a binder liquid composition that is used before each layer when applying finishing materials – whether it is an intermediate layer of putty or a layer of finishing, in the form of painting or wallpapering. The composition has two main tasks:

• increase the adhesion of the wall surface;
• strengthen crumbling or loose surfaces and level them (if the wall is loose, the mixtures fill the porous structures and bind them, the base for finishing work becomes stronger).

The primer has additional positive effects. It helps to save paint or wallpaper glue – by about 20%, since the walls after the primer absorb the subsequent compounds worse. Also, the primer gives a uniform tone to gray walls and masks stains that may be visible under light wallpaper..

According to the form of release, the primer composition is:

• dry: then it must be diluted with water in the proportions indicated in the instructions;
• concentrated: requires dilution;
• ready: you need to open the container and stir the contents.

Which primer to choose

There are several types of primer used for interior decoration.

Acrylic primers

The most commonly used universal acrylic primer, which manufacturers claim is suitable for all surfaces. The mixtures are also good because they practically do not smell and dry quickly (2-3 hours). In turn, they are divided into 3 subspecies:

• strengthening compounds – create a thin, sticky film on the surface;
• deep penetration emulsions – designed for walls with a crumbling surface, which must be additionally strengthened (the binding particles in the primer are smaller, and this allows deeper penetration into the surface);
• compounds with increased adhesion, required for the treatment of walls when gluing heavy wallpaper, such as bamboo, some vinyl, non-woven.

Latex primers

They are also referred to as universal formulations. According to their characteristics, they are similar to acrylic: they lie evenly, dry quickly, and provide reliable adhesion. Latex primers are more flexible and dense, but have less adhesion. But they better bind crumbling surfaces (for example, old plaster) and are good in rooms with high humidity.

Primers for wood and metal

For a wooden surface, it is better to take an alkyd primer, and a glyphthal one is suitable for both wood and metal. They dry for a long time (within a day). Universal can also be used, but special primers are better “tuned” for wood and metal materials. So if you plan to repair in the garage, in the country or in the household premises, it is better to opt for these mixtures.

These are just the main groups of compositions. Components are often added to them, which give the mixtures additional properties. For example, acrylic antiseptic primers prevent the formation of mold, glyphthalic primers prevent the development of corrosion. When painting, you need to take into account not only the type of surface, but also the type of paint for which the walls are prepared: the bases must match. Suitable for all types of paint are synthetic primers made of latex or polyvinyl acetate dispersion.

How to calculate the amount of primer

The recommended rates vary greatly depending on the concentration of the product, its type, and the type of surface to be treated. So, for 5-7 square meters, a kilogram of a universal mixture of deep penetration is required, if the composition is strengthening, the same amount will be enough for 5-15 square meters (if it is simpler: about 200-400 ml of solution is needed per 1 square meter). More accurate figures are calculated on an individual basis and largely depend on the ability of the treated surface to absorb liquid. You can calculate the amount of material step by step:

1. Calculate the average. The packaging always indicates the rate of material consumption per 1 square meter, so it will be easy to do this: measure the wall area and multiply by the indicated number of grams.
2. Determine the absorbency of the substrate (if the wall is porous and easily absorbs liquid, more mixture will be needed). This can be done by sprinkling a small area with water from a spray bottle: if it is quickly absorbed and a dark spot remains on the wall, the absorbency is increased. If the liquid runs off, you won’t need a lot of primer.
3. Calculate how many layers are required. Usually 1-2 layers are applied. It is necessary to open the wall with a primer a second time if: very loose surfaces, with a large number of stains that need to be hidden, when using a waterproofing compound. If the decision is made to prime the walls 2 times, then the second layer will need about half as much primer as the first one, since after the first layer the absorbency of the wall will be less.

Important! Principle: the more, the better, it does not work with a primer. No need to get carried away. Conscientious 5 layers will lead to the formation of a film that is too dense on the wall, on which glue or paint will not adhere well, 2 layers are quite enough.

Preparing walls for priming

Before priming, the walls must be thoroughly cleaned: remove the old wallpaper (if they are reluctant to leave their home, you can moisten them with water and use a scraper), clean off the whitewash, and knock off the paint. Ideally, a completely clean surface with no traces of coatings should remain. After rinsing the surface (this will help remove traces of glue, dust), let it dry. Next, check for mold on the walls. If there is, it must be removed. We told you more about this in the article “How to get rid of mold on the walls”. The primer is best used with antifungal additives to help prevent new mold. Cracks and chips on the walls should be scrubbed with a spatula to remove crumbling elements. The most noticeable damage can be putty (sometimes there are deep cracks between the ceiling and walls, then you will have to use plaster). How to putty walls for painting and wallpaper, read our material.

Important! The primer must be applied both under the putty and on the putty after it dries.

Work technology

There are no particular problems with applying the primer. It seems to paint the walls with it. However, there are some subtleties to be aware of..

For work you will need:

• primer;
• small brush;
• roller (foam rubber is quite suitable, if you choose with a pile, then not long);
• a bucket, a basin or a tray-ditch (the mixture is liquid, so it is better to use special containers that are equipped with a ribbed “ladder” against which you can squeeze the brush and roller);
• gloves;
• protective mask (you can use a regular medical bandage).

The primer is a safe but liquid formulation that is easy to spray. Therefore, it is better to wear clothes that cover both arms and legs as much as possible. If the mixture gets on the skin, wash it off immediately..

Priming step by step:

• Stage 1. Prepare the solution in accordance with the directions on the package. It is better not to stir the whole amount, but to do it in portions.
• Stage 2. Brush on corners and hard-to-reach places.
• Stage 3. Apply the primer to the walls with a roller, running it vertically (this will help to avoid dripping). You can add a little color to the colorless composition so that you can see on the wall where the mixture already exists.
• Stage 4. Wait for the allotted time (indicated on the package) for the primer to dry.
• Stage 5. Apply a second layer in the same way.
• Stage 6. Let it dry.

The wall is ready for further work.

Helpful hints:

• take the furniture out of the room before work, if it is not possible, cover it and the floor with film or cardboard;
• if the primer is spilled, immediately rinse this place with water, otherwise it will dry out and it will be more difficult to remove it;
• make sure that “puddles” of the mixture do not accumulate in the recesses on the walls;
• when working, make sure that the composition lays down evenly and covers the entire surface;
• wash brushes, rollers and containers immediately after work.

How to make a primer yourself

You can do the primer yourself. The easiest option is to use a composition instead, which will perform the same functions: increase the adhesion of the wall to wallpaper or paint. Wallpaper glue diluted with water is suitable for wallpaper. Many packages indicate that it can be used as a primer and give the proportions in which it should be mixed with water. Typically, you need to add twice as much water as you would for making wallpaper glue. Before work, you need to pour the right amount of glue into the water, stir, wait until it swells slightly and apply to the walls.

PVA glue also copes well with the task: for 2 parts of water you need to take 1 part of glue and mix well. The mixture should be made in small portions, as the finished product quickly becomes unusable. Before painting, you can prime the walls with paint well diluted with its own base. For example, water-based paint should be diluted with water, enamel with solvent or white spirit. To do this, you need to pour a little paint into a clean container and gradually pour liquid into it, stirring constantly until the desired consistency.

It should be borne in mind that universal mixtures are multifunctional and easier to use. Homemade primers need to be mixed properly and also do not have all the properties that specialized formulations have. Therefore, for quality work, it is worth giving preference to the compositions that are provided for a certain type of work..