How to prepare

Table of Contents

Getting your walls ready for coating

A good quality of the surface is crucial for a successful paint job. Therefore the surface has to be cleaned, checked for any defects and prepared accordingly.

Smooth surfaces without wallpaper or coverings

Dusty soilings

  • Mechanical cleaning of the surface by means of wiper, broom, vacuum cleaner.

Greasy soilings

  • Clean the surface with lye.
  • Use washing soda or trisodium phosphate cleaner (TSP). Cleaning solutions are less suitable.
  • Rinse with water.

Lye TSP

Short, fine cracks and small holes

  • Fill with gypsum based spackling paste.
  • Even and sand fillings to level.
  • Or: fill with acrylic sealant from the cartridge.

Gypsum based spackling paste Acrylic sealant

Long and wide cracks and large holes

  • Fill with gypsum based spackling paste.
  • Even and sand fillings to level.

Procedure a (less elaborate and less sustainable)

  • Reinforce the filled and smoothed cracks using drywall tape.
  • Prime the reinforcements.
  • Smooth the edges of drywall tape using spackling paste.
  • Even and sand the fillings with caution to the drywall tape.

Procedure b (more elaborate and more sustainable)

  • Cover the whole surface with paper wall liner.
  • For this task engage a specialist.
  • Or: How to apply paper wall liner.

Drywall tape Primer Paper wall liner

Yellowing by nicotine

  • Cleaning the surface with lye.
  • Use washing soda or trisodium phosphate cleaner (TSP). Cleaning solutions are less suitable.
  • Rinse with water.
  • Apply stain blocking primer.

Soda TSP Stain blocking primer

Yellowing by water

  • Repair the cause of the water intrusion.
  • Allow to dry the spots. Depending on the depth and extent of the water damage this can take days or weeks.
  • Apply stain blocking primer.

Stain blocking primer

Check the condition of the existing paint film

Water-soluble paint film

Procedure a

  • Wash down the existing coating with water and sponge.
  • Thick layers of paint wash down in several passes.

Procedure b

  • Paint over the water-soluble coating with a paint of the same type (Glue-bound distemper).

Water-soluble coatings are an unsuitable substrate for film forming coatings and - therefore they should not be painted over with emulsion, latex or varnish.

Glue-bound distemper

Poorly adhering paint film

  • Push off damaged areas of paint with a putty knife.
  • Fill the edges of the coating with spackling paste.
  • Even and sand fillings to level.
  • Apply primer.
  • Spackling paste Primer

Chalking paint film

  • Mechanical cleaning of the surface by means of wiper, broom, vacuum cleaner.
  • Apply primer.

Primer

Smooth and shiny paint film

  • Treat the surface with lye.
  • Use washing soda or trisodium phosphate cleaner (TSP).
  • Rinse with water.

Soda TSP

Surfaces with wall coverings and textured surfaces

Greasy soilings

  • Clean the surface with lye.
  • Use washing soda or trisodium phosphate cleaner (TSP). Cleaning solutions are less suitable.
  • Rinse with water.

Soda TSP

Dusty soilings

  • Mechanical cleaning of the surface by means of wiper, broom, vacuum cleaner.

Loose edges of the wall covering

  • Slightly lift the loose edges of the wall covering with a putty knife.
  • With a flat paint brush abundantly give wallpaper paste under the loose edges and spread it carefully.
  • Firmly press down the wall covering with the brush towards the edges, to simultaneously expel the supernatant paste.
  • Remove the supernatant paste with a damp sponge.
  • Damp wall coverings are very sensitive to mechanical stress. Therefore, do not use sharp-edged tools for this work.

Flat paint brush Wallpaper paste

Bubbles in the wall covering

Procedure a

  • With a sharp knife slit the bubble.
  • Slightly lift the loose edges of the wall covering with a putty knife.
  • With a flat paint brush abundantly give wallpaper paste under the loose edges and spread it carefully.
  • Firmly press down the wall covering with the brush towards the edges, to simultaneously expel the supernatant paste.
  • Remove the supernatant paste with a damp sponge.

Procedure b

  • With a syringe abundantly inject wallpaper paste under the bubble.
  • Firmly press down the wall covering with the brush towards point of injection, to simultaneously expel the air and supernatant paste.
  • Remove the supernatant paste with a damp sponge.

paint brush Wallpaper paste

Holes and damages in the wall covering

Procedure in case of unstructured, smooth wall coverings

  • Choose the patch in identical or similar quality as the wall covering. The patch should cover the damaged area all around to palm width.
  • With one hand fix the patch to the damaged area and with a sharp knife cut both the patch and the wall covering.
  • Usually it's better to keep the shape of the cuts bevelled.
  • Remove the damaged and cut-out piece of the wall covering.
  • Eventually fill damages in the wall with spackling paste. Restrict the filling on the bare spot and do not work the paste into the wallpaper.
  • Even and sand fillings to level.
  • With a flat brush apply paste.
  • Apply the patch and firmly press it down with the brush towards the edges, to simultaneously expel the supernatant paste.
  • Remove the supernatant paste with a damp sponge.
  • Allow to dry.

Spackling paste Flat paint brush

Procedure in case of woodchip wallpaper and textured wall coverings

  • Choose the patch in identical or similar quality as the wall covering. The patch should cover the damaged area all around to palm width.
  • Remove damaged parts of the wall covering carefully tearing.
  • Eventually fill damages in the wall with spackling paste. Restrict the filling on the bare spot and do not work the paste into the wallpaper.
  • Even and sand fillings to level.
  • Tear the edges of the patch in irregular shape.
  • Paste the patch with a flat paint brush.
  • Apply the patch and firmly press it down with the brush towards the edges, to simultaneously expel the supernatant paste.
  • Remove the supernatant paste with a damp sponge.
  • Allow to dry.

Damp wall coverings are very sensitive to mechanical stress. Therefore, do not use sharp-edged tools for this work.

Spackling paste Flat paint brush

Tools, products and applications

Lye

Other designations: Sodium carbonate, Washing soda, Soda ash, Soda crystals

Cleaning surfaces

  • Dissolve 1 tablespoon of soda in 1 litre of hot water.
  • Apply with a sponge.
  • Leave on for 1 - 2 minutes.
  • Rinse twice with water.

Desired result: the surface is free of grease and matte.

Treating glossy surfaces with lye

  • Dissolve 2 tablespoons of soda in 1 litre of hot water.
  • Apply with a sponge.
  • Leave on for 1 - 2 minutes.
  • Rinse twice with water.

Desired result: the surface is free of grease, matte and has a good grip.

Lye has an alkaline effect! Note the application and safety instructions on the packaging. Wear rubber gloves and safety goggles.

TSP (Trisodium phosphate)

Other designations: Sodium phosphate, Degreaser

To matte and clean old paint based on oil or resin. Breaks the gloss of hard and shiny resin paints providing a surface suited for the following application of paint. Available as a liquid, or as a powder. Preferably use TSP containing product whose components are biodegradable. Note the application and safety instructions on the packaging.

Drywall tape

Other designations: Fiberglass drywall tape, Paper drywall tape

Self-adhesive tape made of paper or fiberglass mesh. The tape covers cracks and joints and it can be smoothed short after the application. Try to apply the tape without wrinkles or overlaps.

  • Cut the tape in handy short pieces.
  • Peel off the cover paper by a few inches and fold it back.
  • Align the tape at the crack and press the sticky the end to the wall.
  • Peel off the backing paper piece by piece and following this, stick the tape piece by piece to the wall.

Paper wall liner

Other designations: Wall liner, Lining paper, Wallliner™.

Paper wall liner made of a combination of cellulose and textile fibers. Such fleeces are durable and able to cover smaller cracks. Wall liners are subsequently coated with paint.

> How to work up paper wall liner

Stain-blocking primer

Other designations: Sealer.

Stain-blocking primer is used to bind and to cover yellowings and soilings, to the extent they are not cleanable. This prevents the bleeding of the soilings through the fresh layers of paint. There are solvent-free and solvent-based sealers available. In most cases a solvent-free primer will do the job. Maybe the sealing has to be to repeated.

Desired result: After drying, the surface shows no discoloring anymore.

Gypsum based spackling paste

Other designations: Gypsum based putty, Gypsum filler

Filler in the form of powder on the basis of gypsum and usually with additions of cellulose glue. Gypsum based filler adheres also on little absorbent substrates, does not shrink and can be sanded after drying. Such fillers should be used in dry interiors only.

> How to work with fillers

Acrylic based filler

Other designations: Acrylic based putty.

The resin-reinforced filler paste. Acrylic based filler adheres also on non-absorbent substrates, shrinks somewhat and can be sanded after drying. It's advantageous to apply acrylic filler in thin layers. These dry quickly, while thick layers harden very slowly.

Acrylic sealant

Other designations: Acrylic filler cartridge, Flexible filler, Gap Filler, Joint sealer.

Acrylic based filling material supplied in cartridge form for gun application. With such fillers cracks, joints or connections can be filled, which are slightly stressed by stretching. The duration of the drying is dependent on temperature and humidity. Use products which are labeled "paintable".

Acrylic sealant shrinks during drying, so overfill the gaps. After the filler has dried (the next day), cut away the supernatants with a sharp blade.

Primer

Other designations:

Primers reduce and equalize the absorbency of substrates. To imbuing well into the ground, they are of low-viscosity and usually the material should be further diluted. Because of that consistency, primers are easier to apply with a large brush (ceiling brush) than with a paint roller. Preferably use a water-based primer.

  • Repeat the priming process wet-in-wet till the ground is saturated.
  • Work with the empty ceiling brush until all primer is absorbed and no dripping happens anymore.
  • Allow to dry at least overnight.

Desired result: The surface is slightly absorbent, isn't glossy and doesn't chalk.
Ceiling brush

Glue-bound distemper

Glue-bound distempers contain as binder cellulose glue and water as solvent. Cellulose glue remains water-soluble after drying, so distemper also remains water soluble. While distemper can easily be repainted with the same kind of paint, distemper coatings shouldn't be painted over with different varieties of paint.

Ceiling brush

A brush with a rectangular board of the size of a palm and long bristles. Ceiling brushes are used for applying primers, paint or paste. With a ceiling brush low-viscosity materials may be applied cleaner than with the paint roller.
For this, the ceiling brush but must be of good quality. The main criterion for a good brush are fine, long bristles whose ends are finely split.

Flat paint brush

A brush of flat rectangular cross-section. It is available in different sizes and varieties of bristles. Flat brushes with synthetic bristles are suitable for water-based paints, flat brushes with natural bristles are also suitable for solvent-based paints.

Wallpaper paste

An aqueous glue made of methyl cellulose. Due to the various types of wallpapers there are different types of wallpaper paste available. Decisive for the choice of wallpaper paste are the manufacturers notes on the roll of wallpaper.

Author: Paul Zoller,

Date:

Emacs 26.1 (Org mode 9.1.13)