Chemical Stains & Finishes for Wood

¶ We hear and read about acid stains but just what constitutes this group of materials is not clear to a great many. One reason for the confusion of thought is the incorrect use of the word "acid" to describe factory-prepared aniline water stains. The aniline dye used in coloring these water stains is designated among manufacturers as "acid anilines" because an acid chemical process was used in their preparation in the concentrated form.

¶ Chemical stains are water stains, as a rule, and they are of two kinds of acid solutions and alkaline solutions. In other words, there are a number of acids which when dissolved in water will color wood, and there are a number of alkalies which when dissolved in water will color wood. These acids and alkalies will be listed and described later on in this chapter.

¶ Like other stains, the chemical stains have their advantages and disadvantages. For some work they are unequalled by any other stain, but they are not convenient nor practical for other classes of work.

¶ The trend of the times in furniture factories is, perhaps, toward the greater use of chemical stains, although the aniline and coal tar stains are used today in far greater volume than any other class of stains. We have seen that the finishing of wood trim in buildings follows more or less closely the colors produced on furniture and to some extent the methods employed by furniture finishers. Therefore a knowledge of the chemical stains is of value to all, even though the house painter and finisher of woods may find the chemical stains not convenient for the average job. On jobs which include a very large amount of trim, especially when that trim can be finished before erection, as on modern office and other public buildings, the chemical stains may well be considered for the saving in cost which they will make.

¶ There are certain colors of finished furniture which can only be matched by the use of chemical stains, and when very great penetration of the wood is necessary in order to make the finished color withstand great wear, the chemical stains cannot be equalled. The anilines and coal tar dye stains, however, are in most cases equal to the task of duplicating practically any color wanted when the finisher is skilled in their blending.

¶ The use of chemical stains really involves a process, though a simple one as a rule, and also adequate equipment for handling the stains and the articles of merchandise or pieces of trim lumber upon which they are being used. An understanding of the characteristics of each of the chemicals is necessary to using them safely and effectively, although it is not by any means necessary that one be a chemist to use them to good advantage, Some of these chemicals are dangerous to the skin and it is well to make a habit of working with rubber gloves or to coat hands, face and all exposed skin with vaseline, petrolatum or heavy motor oil. Care must be taken not to get any of this grease or oil on the wood to be stained, however.

¶ The mixing of acids and strong alkalies should also be done with caution until one knows what the consequences are. For instance, it is entirely safe to mix sulphuric acid with water if only a few drops at a time of the acid are put into a large quantity of water. But reverse the method, pouring water into a quantity of sulphuric acid and the result is a small explosion which sends a shower of acid into the air and perhaps into your face and onto your hands. Sulphuric acid burns the skin and destroys cloth. And again, the fumes of hydrochloric (muriatic) acid are dangerous to breathe. Many of the chemical solutions appear harmless when only occasionally they come into contact with the skin, but frequent contact soon proves that they make sore hands and that there is danger of blood poisoning from the entrance of some acids into cuts, sores or scraped places on the skin. The use of rubber gloves eliminates these risks. Before using any strong chemical it is well to learn from your druggist or any chemist what the actions of those substances are when mixed or used as you propose using them.

¶ The chemicals used for staining purposes are not always easy to secure conveniently. Some of them are carried by paint supply stores, some by the local druggists. Some of them the druggist will have to order from a wholesale stock.

¶ Today the chemical stains are not used to any practical extent by the wood finisher doing the finishing of wood trim in buildings. In the building trades the wage scales are high enough to make contractors devote their major efforts to saving time rather than to cutting minor costs of materials. Even the furniture factories use other stains, mostly the aniline and coal tar dye stains. The house painter's money is made by doing many jobs at small profits on each. The cost of stain represents only a small part of the total cost of his jobs. Wages constitute the large item of cost. "What little he might save by using a few gallons of home-made stain might be lost several times in wage cost.

Next Page: Tips on Using Chemicals for Finishing.