_Alkyd resins in molding compositions and other uses._—The alkyd resins are much less important as binders in molded articles than in coatings and finishes. Conversion of the resin to the insoluble infusible form is extremely slow, requiring days as compared with minutes for the tar-acid and urea resins. The alkyds are used as binders for flake, powder, and split mica to produce insulation material of high electrical strength. Other uses are in the production of linoleums; gaskets; brake linings; laminated fabric, paper, and cardboard sheets; printing inks; and coated paper, textiles, and leathers. Pigments and solvents in alkyd finishes. Since the alkyd resins are largely used in surface coatings and finishes and since this application in this field is producing great changes in the industry, it is appropriate to consider the effect of their use on other materials. The average alkyd resin consists of 50 percent glycerol phthalate modified with 50 percent oil, fatty acid, natural resin, or synthetic resin. The alkyd and modifier are dissolved in a solvent, usually a coal-tar light oil such as toluol, or xylol, or a petroleum solvent, and pigmented with titanium dioxide or other pigment. Highly basic pigments such as zinc oxide, carbonate white lead, whiting and aluminum hydrate (all important pigments in the conventional types of finishes) are not used in alkyd finishes. Production in the United States. Prior to 1929, the domestic production of resins from phthalic anhydride was confined largely to one maker. The quantities produced were relatively small. In 1929 there were three producers, the volume of whose production exceeded one million pounds for the first time. Beginning with 1933 the Tariff Commission collected and compiled production and sales statistics for these resins. They are shown in table 7. TABLE 7.—_Alkyd resins from phthalic and maleic anhydride: United States production and sales, 1933-37_ --------+-----------+------------+------------------------------------ | | | Sales Year | Number of | Production +------------+-----------+----------- | makers | | | | | | | Quantity | Value | Unit value --------+-----------+------------+------------+-----------+----------- | | _Pounds_ | _Pounds_ | | 1933 | 6| 9,930,705| 3,654,854 | $673,890 | $0.18 1934 | 10| 15,219,247 | 7,084,602 | 1,022,436 | .14 1935 | 15| 34,312,713 | 15,836,942 | 3,482,078 | .22 1936[1] | 31| 46,952,452 | 24,252,535 | 5,312,121 | .22 1937[1] | 39| 61,254,019 | 34,738,295 | 6,864,194 | .20 --------+-----------+------------+------------+-----------+----------- [1] Includes resins from maleic anhydride.