This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Varnish, paint, etc., no matter how old and hard, may be softened in a few minutes so that they can be easily scraped off, by applying the following mixture:
Water glass.......... 5 parts
Soda lye, 40° B. (27
per cent).......... 1 part
Ammonia water...... 1 part
A patent has been taken out in England for a liquid for removing varnish, lacquer, tar, and paint. The composition is made by mixing 4 ounces of benzol, 3 ounces of fusel oil, and 1 ounce of alcohol. It is stated by the inventor that this mixture, if applied to a painted or varnished surface, will make the surface quite clean in less than 10 minutes, and that a paint-soaked brush "as hard as iron" can be made as soft and pliable as new by simply soaking for an hour or so in the mixture.
Pour enough of oil of vitriol (concentrated sulphuric acid) over powdered fluorspar in an earthen or lead vessel, so as just to cover the parts whereby hydrofluoric acid is generated. For use, dip the article suspended on a wire into the liquid until the enamel or the tin is eaten away or dissolved, which does not injure the articles in any way. If heated, the liquid acts more rapidly. The work should always be conducted in the open air, and care should be taken not to inhale the fumes, which are highly injurious to the health, and not to get any liquid on the skin, as hydrofluoric acid is one of the most dangerous poisons. Hydrofluoric acid must be kept in earthen or leaden vessels, as it destroys glass.
The following compound is given as one which will clean paint or varnish from wood or stone without injuring the material:
Flour or wood pulp.. 385 parts Hydrochloric acid... 450 parts Bleaching powder.. . 160 parts
Turpentine........ 5 parts
This mixture is applied to the surface and left on for some time. It is then brushed off, and brings the paint away with it. It keeps moist quite long enough to be easily removed after it has acted.