Different Ways of Removing Finishes From Timber
Timber members in many historic buildings would have been painted or varnished subsequently and it may become necessary to strip these coatings. There are several methods for removing an old finish, some more complex than others. This blog post outlines some of the ways to remove the unsympathetic finishes from timber elements in buildings.
List of Contents
For any finish, the first step is to identify the old finish. Even the paint (available in green and black) in some historic buildings may not be the enamel paint in a conventional sense. Test the finish first with denatured alcohol. If the finish liquefies, then it is shellac. If it gets soft, then it might be a combination of shellac and lacquer. Apply lacquer thinner to the surface and if it liquefies, then it is lacquer. Before going to further detail, let us first see how to apply the solvents that are used for removing timber finishes.
1. How to Apply Any Solvent for the Removal of the Timber Finishes?
The exact method of applying the solvent may vary slightly, but broadly, the following procedure may be adopted;
Apply the correct solvent to an area of the furniture. Do not brush, rub on it gently with a piece of cloth.
Always work in one direction only.
Leave the chemical in the timber for about 15 seconds. This time may vary with the solvent and the coating. In the case of paint remover, it can be a few minutes.
Then wipe off with a cloth. You can remove it completely if the finish comes off readily.
The speed while applying is important because many of the solvents such as alcohol and lacquer thinner evaporate rapidly.
It is best to work in sections and keep changing the cloth for better results.
In the case of a vertical section, start at the top and work your way down.
In the case of old doors and windows, there may be many coats of paint or varnish. Patience is required for the removal of the coating without damaging the timber pieces.
Now, the next section is a brief about how to remove different types of finishes from timber members.
2. Removal of Different Types of Timber Finishes
2.1.Removing Shellac and Lacquer
Aggressive chemicals are not required for the removal of these finishes. Always apply the chemicals to only a small section of the timber piece which is not visible normally. Now, Shellac can be removed with denatured alcohol and Lacquer can be removed with lacquer thinner. A 50-50 mixture of denatured alcohol and lacquer thinner can remove a combination of shellac and lacquer.
2.2. Removing Paints and Varnishes
No preservative or curative treatment is feasible on a painted surface. Removing varnishes from paintings and other sensitive objects should not be attempted in this fashion. That requires the skills of painting conservators who have formal training and practical experience. There are three methods of removing varnish and paints from timber surfaces;
The old paint can be scraped off. One can use portable equipment such as a rotary sander or it can also be done by hand. The main drawback of sanding is that it removes some of the wood surfaces underneath the paint. If the person doing the work is not experienced, then it can cause a lot of damage to the timber surface. If one is working with a fine piece of furniture, sanding is recommended. It can be used only on extremely rough jobs.
By Using a Chemical Paint or Varnish Remover
Commercial paint removers based on methylene chloride are available in the market. Make sure that these chemicals are not based on strong alkalis like sodium hydroxide. They are recommended only for removing paints from impervious materials such as granite. Cover the area with waxed paper to slow down the evaporation of the chemical.
By Using a Blowlamp
One can also remove paint with a blowlamp which destroys the film in the old paint. This makes it simple to scrape away the paint as soon as it has been heated. The blowlamp should not be held in the same position for long enough to burn the timber.
Those flecks of paint inside the pores have to be removed while they are still soft. Do not use steel wire brushes because they are stiff and will scratch the timber. A toothbrush or plastic tools may be used to clean the crevices and carvings. One should take care not to gouge the timber.
Click to know more about the Saukar Masjid
Removing shellac and lacquer is the easiest to remove. The tougher finishes such as paint and varnish are more common and can be removed with any of the above-mentioned methods. Many of the chemicals that are being used, are inflammable and have toxic fumes. Always wear rubber gloves and protective goggles. Preferably the work should be done outdoor. When working inside, all the windows should be opened and fans should be switched on. Such methods of refurbishing existing timber members and reusing them can help to retain the original character of historic buildings. It can also help save the amount of timber used and blend well with the building.
Click to know more about New Model Coir Society
For more information on how to conserve timber members, visit the blogs given below: