_Semidrying alkyd resins._—Cottonseed oil is the principal modifier in semidrying alkyd resins. Alkyd resins of this type are used in finishes requiring maximum gloss and color retention. When baked on metal at high temperatures they show no tendency to wrinkle. They are used as reinforcing agents to increase flexibility and durability, and to plasticize other finishes. _Nondrying alkyd resins._—The nondrying or nonoxidizing alkyd resins are those containing a nondrying oil, such as castor oil or coconut oil, or the fatty acid of a nondrying oil, such as stearic, palmitic, or oleic acid. Nondrying oils make the resin less sensitive to heat hardening and impart greater flexibility. These resins are used principally as plasticizers in nitrocellulose lacquers. In this use they have the advantage of better retention of plasticizing efficiency than other plasticizers, many of which are lost by evaporation, migration, absorption, or oxidation. These modified nitrocellulose lacquers, either clear or pigmented, are used for coating wood, composition board, cloth, paper, rubber, leather, and similar surfaces. _Miscellaneous modified alkyd resins._—This group includes alkyd resins modified with materials other than those already discussed. To date (1938) there has been little, if any, commercial production of such resins. There are many modifiers which have been suggested and which might be used but for the fact that they are too expensive. Among these are butyl alcohol and benzoic acid. _Alkyd resins in water dispersion._—Emulsions of alkyd resins in water are now available for use in clear and pigmented coatings. These are sold in the form of paste containing 40 to 50 percent solids and are diluted with water at the time of application. They are especially suitable for coating porous surfaces, such as brick, concrete, plaster, stucco, and masonry of all kinds. They are applied by brushing or spraying and they combine the ease of application of water paints with the durability, washability, and hardness of oil paints. They dry quickly, and the dried film cannot again be dissolved or suspended in water; the coating can therefore be washed or, after several weeks, scrubbed with cleansers. Compared with oil paints, they give better coverage, are easier to apply, and cost appreciably less. Compared with other types of water paints, such as kalsomine, they give a glossier coating of greater durability and superior appearance; they seal porous surfaces better; their covering capacity is greater; and their applied cost is slightly less per square yard of surface. Coatings of this type may be applied directly over fresh plaster without a sizing coat, since they allow the curing of the plaster to continue. The usual paint pigments may be incorporated. A special use of the water dispersed alkyds is on asphalt or tar since they are nonbleeding in the solvents of these materials. This quality permits their use for traffic and zone markers on streets.