During the repair work, the bulk of the time is spent not so much on applying finishing materials as on preparing the basis. Removal of the old paint is one of the most time-consuming and labor-intensive operations. Fortunately, there is an alternative way of carrying out work - a primer for old paint. About how to primetovat surface and what mixtures to use, we will discuss this article.
If the old paintwork is cracked and peeled off, no painting of such surface in the old layerit can not go. However, often the coating retains good adhesion, and such that the paint is very difficult to remove with a scraper. In such cases, it is possible to primer the old paint.
It must be borne in mind that the paint gives the surface a smoothness. The surface becomes low-porous. Thus, adhesion, that is, the ability of dissimilar materials to bond, deteriorates significantly. If the paint does not hold well, a new repair will soon be needed. To eliminate such problems, special soils are produced. The most popular brands of such soils will be described in more detail below.
In order to understand why you need priming, you need to consider the differences of the primer from the paint and varnish composition.
There are only two such differences, but they are of decisive importance:
- There are much less pigmenting substances in the ground.
- The mixture includes special additions, thanks to which the paint acquires the necessary properties, including improved adhesion between materials, accelerated drying, antiseptic qualities.
So, the paint is not capable of replacing the soil. However, in some situations, it is possible to use water-based paint instead of a primer. The proportion should be 1 to 1. There is a special priming and simultaneously coloring compound for metal "Zinga".However, it is often economically inexpedient to use paint instead of a primer, as paints and varnishes are always more expensive.
Application of primer
For priming to ensure high quality of work, it is necessary to observe a number of conditions:
- The coating should not be glossy. If it is still glossy, you will need its rough grinding.
- The paint should not peel off. Where the paint is peeling, it must be removed.
Please note! If a new paint material of the same kind as the old one, you can do without priming. For example, acrylic water-based compounds are well combined with acrylic and latex-acrylic paints. On the oil base, it is possible to apply oil paint, on alkyd - alkyd composition, etc. But with the correct preliminary preparation, you can paint with acrylic paint in oil.
Preparing the base
Before applying the primer, prepare the substrate.
- First remove the flaking paint from the surface. We remove not only the peeling places, but also 5-10 centimeters of space nearby.
- We clean the surfaces of dust and dirt. To do this, we use a moistened sponge and a household chemical.
- We work out the cleaned place with a universal primer and apply the putty. So we get rid of unevenness on the surface. Do not forget to level out all the chips and scratches.
- We finish the preparatory work by grinding the filled surface. For this we use fine-grained nazhdachkoy. We should get a perfectly even coating.
The preparation and application of the primer is carried out in the following order:
- Stir thoroughly. If this is not done, the surface will not be uniform.
- Priming compositions are characterized by a thick consistency. To make it easier to apply the primer, it is recommended to slightly dilute it with water. However, the proportion of liquid should not exceed 10 percent.
- Fill the prepared solution in a container. It is best to use a special flat paint pallet.
- Wet the roller in the priming mixture and squeeze it on a special area( if there is a paint pallet).
- Apply the primer to the surface with a roller. Apply the solution evenly. The layer should not be too thick. We try to avoid streaks. To do this, carefully rub the composition over the surface.
- Places in which it is difficult to reach the roller, we process with a brush.
- To ensure proper adhesion, after drying the first layer, we apply the second one. The optimum temperature for drying the soil is 20-23 degrees above zero, and the relative humidity should be within 70-80 percent. In such conditions, the surface will dry in about an hour.
- Work is completed, it remains only to rinse the tool in water.
Warning! If the priming solution has got into the eyes, you should immediately rinse them under running water. And the washing should be done within 10-15 minutes.
When the primer has dried, you can start painting the surface. However, here it is necessary to clarify: the time of conditional and final drying is different for different manufacturers. Specific figures can be obtained by reading the instructions from the manufacturer. Also, you need to make a correction for the characteristics of the environment( humidity and air temperature).
Please note! Surfaces, previously painted with water-dispersion paints, do not need to be primed.
Overview of well-known brands
Below we will consider the consumer properties of several well-known brands of primers, presented on the Russian market.
This primer is used before applying acrylic paint. Specially designed for processing not only absorbent substrates, but also old paints.
The following characteristics of this soil can be distinguished in the manufacturer's instructions:
- A guarantee is given for compatibility with old coatings, painted with enamels based on pentaphthalic binder, nitrocellulose and oil paints.
- When the soil dries, a milky white uniform film remains on the surface.
- The rate of consumption of the material is 200 grams per square meter.
- In case of adding water to the solution, its share should not exceed 7 percent.
- The minimum temperature that the soil can withstand is 40 degrees below zero throughout the month.
- Maximum number of freezing and thawing cycles - 5.
- Drying time "on the touch" does not exceed 2 hours.
- The final drying under favorable environmental conditions occurs within 24 hours.
This composition is highly versatile. As it follows from the instruction, "Neomid" is suitable for water-based paints and any enamel compositions based on organic solvents.
Basic parameters of the soil:
- The composition contains an acrylic aqueous dispersion, a binder polymer, a mineral filler, a pigmentant and special additives to improve the adhesive properties.
- The maximum allowed fraction of water in the solution is 10%.
- Drying at optimum temperature and humidity of air occurs within an hour.
- Composition is applied only by two layers( with a break for drying the first layer).
This primer also applies to universals. A primer is allowed on oil and nitrocellulose coatings, enamel based on a pentaphthalic binder. Also, the primer can be applied to varnished surfaces, concrete substrates."Optilux" is also suitable for preparing walls under the wallpaper label.
Information from the instruction manual of the manufacturer:
- Primer is based on aqueous acrylic dispersion with the addition of pigmenting and polymeric substances, mineral filler, as well as additives to improve adhesion.
- The rate of application of the primer is from 100-200 grams per square meter( the indicator depends on the type of substrate and environmental conditions).
- Drying of the surface occurs within an hour.
- The primer is able to withstand 5 cycles of freezing and thawing.
- Special note from the manufacturer: priming can be done on an unpolished surface.
So, although the representativeness of the review can not be considered sufficient, some conclusions can be drawn:
- First, all primers for oil paints or enamels on organic solvents are made on the basis of acrylic aqueous dispersions.
- Secondly, since the first condition exists, the work is possible only at positive temperatures.
- Thirdly, it is possible to store such primers only at plus temperature.
Priming will greatly facilitate and accelerate the finish, as well as provide long-term quality of repair work. It is recommended to carefully approach the surface preparation before applying the primer. Also, do not save on priming compositions, since it depends on them to no small extent on how long the paint will last.