Dipping Paints for Wood or Metal require to be made specially for either surface, as that intended for wood will not always serve the purpose for metal. The paint for wood requires to contain a pigment that acts as a filler, while tin or smooth sheet iron or steel does not necessarily need it, in fact, it is best without it for certain metallic surfaces. The function of a dipping paint is, first of all, to economize in labor, to cover uniformly any article immersed in it, and to dip freely without leaving fringes of paint at the edges and dry equally all over the surface thus coated.
The most difficult problem in preparing a dipping paint for metal is to have the paint adhere to high ridges and sharp corners or edges, and this is most difficult of all when the paint is to dry with a semi-gloss or full gloss finish. Dipping paints for wood are used in sash and door works, where the finished frames, sashes and doors are dipped in liquid primers to keep them from warping through exposure before being set. These are generally cheap goods bought in liquid form and still further reduced by the addition of ordinary benzine or turpentine substitute. The usual method for making these was to grind zinc oxide and whiting in a mixture of linseed oil and gloss oil, thinning the semi-paste thus produced with petroleum naphtha (benzine) until of good consistency for brushing, because the paint is usually wanted in that form. At the present time, however, the usage is to make a grinding of lithopone and whiting or asbestine powder in raw linseed oil, thinning with gloss oil, drier and benzine, tinting the resulting paint with lampblack in oil a very light gray or lead color. A formula for such a paint that is finding favor is as follows: - Twenty-three pounds lithopone, green seal, 30 pounds bolted whiting and 16 pounds asbestine powder are ground in 15 pounds raw linseed oil and five pounds gloss oil, producing 89 pounds semi-paste, which, after cooling, is reduced to brushing consistency with a mixture of 10 pounds gloss oil and five pounds benzine. The result is 104 pounds of paint, equal to eight gallons. It will not require over four ounces of pure lampblack in oil to make this a very light gray tint. Implement manufacturers use dipping paint for woodwork, such as lawn swings and the parts of farming implements, wagons, etc., and as a rule, where they use the paints mainly to stain and fill the wood and varnish over afterwards also for dipping, they purchase their requirements in paste form, thinning with naphtha, as they can purchase the latter at as low a price as the paint maker. But when it comes to what is called a one-coat dip gloss paint, the paint maker has some show of securing the trade for paint in liquid form. A bright red one-coat gloss dipping paint can be made by grinding para toner with a sufficient quantity of asbestine powder in boiled linseed oil to soft paste form, adding sufficient strong japan drier to make this dry of itself inside of eight or ten hours, reducing this material with a free-flowing mixing varnish of rather thin consistency until the paint drips freely from hard wood, while covering the same uniformly. Or the color and base may be ground in part boiled linseed oil and drier, as in the following formula: -
pounds para toner, blueish, pure,
pounds asbestine, dry powder,
pounds boiled linseed oil,
pounds strong drying japan.
Result, 100 pounds paste - 7 gallons.
For each gallon of this paste add at least two gallons of a mixing varnish as outlined above.
When a blue one-coat gloss dipping paint is wanted, keep lead out of your base, use zinc oxide instead, or still better, lithopone, with enough good suspending material to give the required filling, and then beware of using a mixing varnish made with Manila gum in any case and China wood oil varnish, when zinc oxide is the pigment base. Dipping paint for sheetings of tin, if in red, give best results when a good red oxide, high in percentage of sesquioxide of iron is selected and ground fine in linseed oil with its own weight of a fine quality of magnesium silicate to a medium paste. Should be thinned, if selling price will permit, with spirits of turpentine, otherwise with substitute turpentine or benzine, adding sufficient good japan in either case. If gloss finish is desired one-half of the solvent thinners should be replaced with a good mixing varnish.
A good formula for a dipping paste that will adhere well to tin on drying and not run or sag during the drying process may be made as follows: - Grind to impalpable fineness 250 pounds red oxide, containing at least 90 per cent. sesquioxide of iron, preferably native red, 250 pounds magnesium silicate (known to the trade as asbestine) in 165 pounds boiled linseed oil. To this soft paste add, mixing thoroughly, 10 gallons best drying japan and 40 gallons turpentine or heavy naphtha, as desired, or as selling price wll permit. Result 100 gallons.
The same red paste will answer for a high-grade dipping paint for iron, such as railings, fence posts, or the iron parts of implements, if the 665 pounds of paste is thinned with 15 gallons of good liquid drier and 35 gallons hard drying mixing varnish. These, however, are paints which will find favor only with exacting consumers, because of the price it is necessary to charge.
We do not intend to publish formulas for dope mixtures, and if any paint maker should be interested in such, he can readily work them out from the foregoing by simply using lower priced vehicles and thinners. So far as the pigments are concerned, there is very little to be gained by cutting cost in that direction, and it will be found that whenever too much extending base or base material is used in the pigment it will end in complaints on the part of consumers and loss of trade that was in the first place difficult to obtain.