The initial stage of a coating process is preliminary treatment of the surface. This is the most demanding and long process that is often not given due attention. But it is an obligatory condition to get quality coating. The surface preparation determines quality, hardness, elasticity, and durability of the coating. It contributes optimal adhesion of the paint product to the surface and improves its decorative and protective properties.
It is necessary to pre-prepare the surface with all diligence to make it smooth and even at the end, because diligence influences the result of coating and operation load
Sequence of operations:
New, uncoated but previously plastered surfaces are prepared for application in the following order:
- Removing weak coats of plaster, paint and lime.
- Removing grease, dust and other dirt..
- Coating cracks and making the surface even with plaster.
It is vital to note that preparing to application depends on the type of the surface.
Preparation of previously non-coated mineral surfaces:
- To begin with, the surface shall be cleaned. Make sure that the surface is dry. Treat it with pumice and then with sandpaper with circular moves. Small loose particles of the surface peel off and small defected areas of the surface become even during this procedure.
- The second step is undercoating. The primer makes a loose surface hard, levels its absorbing, improves adhesion of the base layer with any finishing product. In this case, it is wise to use the deep-penetrating Primer “SuperBase” TM Farbex, which provides effective protection against fungi and mould, makes the surface hard and levels its absorbing ability. If the area is larger, you can use deep-penetrating concentrate “SuperBase 1: 4” TM Farbex, which is diluted with pure water in ratio of 1 part of the primer to 4 parts of water.
- 3. The next step: coating of cracks and making the suface even. All cracks and defected areas are smoothed out with putty. After the putty has been completely dried, sandpaper the surface to a smooth surface. Then remove abrasive dust.
- The final stage of the preparation is dust removing. Use a brush or a damp cloth. Paints do not like dust very much (There is too much dust on polished surfaces). That is why the surface shall be dried well before applying a paint product if you have chosen a wet method of dust removing.
- Then undercoat the surface again. Repeated undercoating improves adhesion with a paint product. Use again acrylic primer «SuperBase» TM Farbex or acrylic primer-concentrate «SuperBase 1:4»TM Farbex. It also helps the surface obtaining homogeneous ability to absorb moisture and reducing the consumption of paint..
Preparation of previously coated mineral surfaces:
The procedure of preparation for previously coated surfaces is different.
- There is one binding rule: the surface can not be coated without complete removing of old paint coats.
- You can remove the old paint in a dry way with a scraper or a spatula. If this method is not effective, the surface can be moistened (better with hot water). When the paint gets wet it can be removed with a metal spatula. Another, effective method of removing old layers is to wash the surface with 1-2% solution of hydrochloric acid. All these methods are finished by washing the surface with clean water..
- The procedure for preparing surfaces coated with oil paints, enamels and varnishes depends on the condition of the previous coating. If the paint hasn’t been cracked and keeps well on the coating, then remove dust, grease and other dirt.
- 4. If the old paint is cracked and peeled, it shall be removed with metal spatula or paint-removing products. The paint –removing products are applied to the surface with a thin layer of 2-3 mm and left till coat fluxing (1-2 hours). Loose paint is easily removed with a metal spatula or a scraper
- Then clean the surface of all kinds of dirt, wash with warm water and dry
- The surface is ready for further application as new one.
Preparation of wooden surfaces:
The most important steps in preparation of new wooden surfaces for coating
- First, cut off snubs and gum spots with the help of a chisel and a hammer. Such radical measures are necessary to avoid paint cracks during drying period, as the snubs have a slightly higher build than the main mass of wood. The gum spot used to penetrate through the layers of paint products and appear on the coated surface in a form of stains, so it must be removed. Large openings can be corrected with adjust pieces of timber. Glue them to the base surface with carpenters glue or PVA dispersion. It is also possible to fill defected spots with a rich mixture of minor sawdust and PVA dispersion
- Then remove small scoring and coarseness of the surface with sandpaper. Correct cracks and small traces of distant snubs with a special putty for wood. The color of the putty shall meet the color of timber.
- The next step is to remove oil stains with acetone, refined gasoline or kerosene and dust the surface. We recommend the dry method in this case, so that unsecured wood will not affected with humidity.
- Undercoating is the final stage of preparation of the wooden surface. Undercoat the surface to provide homogeneous ability to absorb moisture of the surface and reduce the consumption of a paint product, as well as to provide antiseptic protection of the surface, using a waterborne primer TM Maxima for this purpose.
- Previously coated wooden surfaces shall be thoroughly cleaned of loose paint, dust, grease and other dirt. Treat the surface with sandpaper and remove abrasive dust. If necessary, undercoat a clean and dry wooden surface with a wood protective primer of TM Maxima.
Preparation of metal surfaces:
- Make sure that metal surfaces are free of rust and dross before application. Detected corrosion, dirt shall be removed by metal brushes, sandpaper or electric sanding machine.
- After that, the metal surface shall be degreased. Wipe the entire surface with any organic solvent (acetone, white spirit, purified gasoline or kerosene) or wash with warm water and detergent to prevent skipping of oily spots, as they are difficult to detect on dark metal.
Preparation of problematic areas:
- Prepare areas, affected with corrosion, with special thoroughness. Corrosion shall be completely removed or isolated to avoid illuminating them on a freshly coated surface. It specially concerns previously sandpapered surfaces, coated with lime or adhesive paint in places where the surface has spots of rust
- The first stage is to remove old paint completely as it is described previously.
- Then isolate rusty and sooty spots, which soaked through the freshly applied coat or remove them. There are several ways to do that.
- The sooty spots shall be washed with 2% solution of hydrochloric acid, then with clean water and after that dried.
- It is possible to isolate spots of rust. Undercoat problematic areas separately in two layers and then undercoat the whole surface again.