Before proceeding with this subject it might be well to have a better understanding of the present methods in formulating compositions for ready-for-use liquid paints or ready-mixed paints, that are termed patent paints by some of the old-line house painters. Some of the original manufacturers of liquid paints forty years ago were in the habit of placing two or three brands upon the market. Only one of these, as a rule, showed their name and address upon the label, while the lower-priced brands were given a fancy name, and often a fictitious address, or they bore the address of the jobber or dealer, handling the goods. The higher grade paints bearing the brand, trade-mark and full name of the makers, up to some six or seven years ago, with but few exceptions, consisted of varying portions of pure white lead (basic lead carbonate) and best American zinc oxide (sometimes even French process zinc oxide) in their pigment portions, containing no extending material, but in place of this, were emulsified with a view of keeping the pigment in suspension, at the same time making it possible to compete in selling price with such brands as had a moderate percentage of extender, such as china clay, magnesium silicate, carbonate of lime, or even barytes, in their make-up. Certain brands of the pure lead and zinc paints were originally based on 20 per cent by weight of dry white lead to 80 per cent zinc oxide, but gradually, because of the demand for better hiding power, these proportions changed, until finally, within the last decade, the figures were either equal proportions or 60 per cent lead to 40 per cent zinc. Other paint makers, again, from the very beginning, even for their best brand, did not use pure lead and zinc alone, but used extenders to a greater or lesser extent and in addition a few per cent of emulsion. With the introduction of such extenders as magnesium silicate, clay or gypsum watery emulsions work disastrously if not confined to the very minimum. In a paint that is composed of pure lead and zinc, however, and which is apt to be stored for a year or more, a moderate portion of emulsion is an absolute necessity and not at all harmful to the paint, as has been proven in the case of at least one prominent brand for over thirty years. The uncalled-for legislation on paint labeling enacted by a few Western States some time ago, the wisdom of which we leave to our readers to judge, has produced a research into paint making, which, to our mind, is still unsettled as to actual results in spite of the great number of test fences put up in different sections of the country and the amount of money expended by paint makers' associations and other interested parties, simply because, so far, the test fences have not given any definite idea as to what any special composition of paint will do in the way of repainting old surfaces. The theory that a paint containing three or four pigments of varying texture or structure is better all around than a paint containing only one pigment may be all right so far as hiding power is concerned, but it has yet to be proven that this also applies to wear and durability in repainting over old painted surfaces. The paint maker has no means of knowing the condition of surface where the consumer intends using his paint, therefore the only way left open to him is to produce a price-worthy article as best he knows how. And, with this in view, we are suggesting the following formulas as the most modern and up to the mark for good wear: -
A. Base for a high-class outside white -
pounds dry lead;
pounds XX American zinc;
pounds magnesium silicate;
pounds refined linseed oil;
1,000 pounds soft paste.
This amount of paste base beaten up in mixer with 193 pounds (equal to twenty-five gallons) refined linseed oil, thirty-seven and one-half pounds (equal to five gallons) pale japan drier and twenty-one pounds (equal to three gallons) turpentine will produce a white of good hiding power for exterior woodwork weighing fifteen and one-half pounds per United States gallon of 231 cubic inches, or, in other words, allowing for waste in handling, eighty gallons of outside white ready for use.
B. Base for a lower priced outside white -
260 pounds dry white lead (or sublimed white lead);
pounds American zinc, XX;
pounds floated barytes;
pounds magnesium silicate;
pounds raw linseed oil;
1,000 pounds medium soft paste.
Placed in the liquid paint mixer and beaten up with 170 pounds (equal to twenty-two gallons) raw linseed oil and fifty-five pounds (equal to seven and one-half gallons) pale liquid drier will produce a paint that may serve as a second-grade outside white, or as a base for making tints of the darker type, weighing sixteen pounds per gallon of fairly stout consistency, a batch of seventy-five gallons. By adding to this batch five gallons of the emulsion which will be described below and five gallons more of raw linseed oil the batch will make eighty-five gallons and the weight per gallon will be reduced to fifteen pounds, while the consistency of the paint will be still stout as before.
For light tints base A is to be highly recommended because of its being a clearer white and of its superior covering capacity. For the emulsion referred to figure as follows on a quantity of fifty gallons: - Three pounds borax and three pounds sal soda dissolved in five gallons boiling water; allow to cool, then add two gallons cold water and six pounds silicate of soda 33 degrees Beaume. Stir well and add sufficient water to make up the above quantity. By dissolving two and one-half pounds animal glue in two and one-half gallons of water, the silicate of soda and cold water mixture can be dispensed with. Another emulsion, really better than this and probably the only effective one for liquid mineral paints, is made as follows: - Dissolve in boiling hot water in separate wooden containers the following: - Ten ounces pale glue, twelve ounces borax, twelve ounces sal soda and twenty ounces white sugar of lead. When solution is complete in each case run the solutions into a barrel that is open at one end, the glue solution first, then rinse the container of glue solution with the soda solution and stir this into the glue solution in the barrel. Next run in the borax and finally the sugar of lead solution. Stir well and add enough cold water to make twenty-five gallons. When used with paint containing lead and zinc no assistant to emulsify is required, but with paint made up of mineral red or brown it is best to add one gallon of rosin varnish (cheap furniture varnish will do) for every two or three gallons of the emulsifier. This will keep the paint well emulsified on long standing when otherwise the mineral pigment will separate from the vehicle and settle and often cake hard in bottom of container.
If a third grade or very cheap quality of liquid paint is desired figure on base B, adding to every 100 pounds of this fifty pounds of whiting in oil (ground at the rate of 75 per cent whiting and 25 per cent oil), thinning this mixture with four gallons raw linseed oil, one and one-half gallons liquid drier and one gallon emulsion. This will produce close to fifteen gallons of paint, weighing thirteen and one-half pounds per gallon, and will make a low-priced white base for dark tints.
The three formulas just given for white can be depended upon for good wear on exterior wooden surfaces and if made for locations where sulphur gases are prevalent the dry white lead in formulas A and B should be changed to sublimed white lead (basic lead sulphate).
The use of emulsion should be avoided or it should at least be used very sparingly in paints that contain large portions of yellow ocher, raw umber and raw sienna, also when gypsum constitutes a large part of the base, all the pigments referred to containing large percentages of hycroscopic moisture, and combined water, hence cannot stand much added moisture.
Inside white in gloss finish is not much in demand, the cheaper gloss whites or mill whites made on a base of lithopone ground in oil and reduced with low-priced pale varnish having taken its place, and the same may be said of interior flat white having been to a large extent replaced or put out of the market by the modern flat wall coatings of which we shall speak later on. As to the inside gloss white, most paint makers put up their outside white under that label, while some made a special white of 33 per cent white lead and 67 per cent zinc oxide (French process) ground in refined linseed oil and reduced with a low-priced white varnish of rosin and turps. This paint varied between fourteen and one-quarter and fourteen and one-half pounds per gallon. The inside flat whites were made up from white lead and zinc in the proportions of one third of the former and two-thirds of the latter, also ground in refined oil, thinned with a pale drier, a small portion of varnish and reduced with spirits of turpentine. To insure good flatting a solution of borax was added in small portions. These paints required a weight of fifteen and one-half to sixteen pounds per gallon in order to cover up well.