Free and bound films (coatings on glass) were prepared of linseed oil and linseed oil paints, dried normally for 10 days, and further dried over calcium chloride. Tests show that free and bound films absorb moisture from damp air and swell, but in far lesser degree than if the films were soaked in water. Film thickness affects absorption in the following ways. 1) Absorption of distilled water decreases as film thickness is increased. 2) On redrying after swelling, thin films shrink in volume more than thick films, but area shrinkage is inde pendent of thickness. 3) Leaching of soluble substances is greater for thin than for thick films. Absorption of water and swelling in free films of unweathered paint are minimum at the critical pigment volume. (Asbeck and Van Loo, (Critical pigment volume relationships, Ind. Eng. Chem., 41 (1949), pp. 1470-5) show that pigment volume at which transition from glossy to glossless condition occurs is a critical point at which marked changes in properties of paint occur). At critical volume, it is presumed that there is only enough vehicle to cover particle surfaces and fill voids. This pigment volume is well above that found in most house paints. Some pigments reduced the absorption of water by free paint films below the absorptiveness of unpigmented oil films. In this class are: Lead white and other lead pigments, antimony oxide, barium sulfate, silica, mica, aluminium. Other pigments made paint films highly absorptive. These include zinc oxide, zinc chromate, Venetian red, most calcium carbonates. A third class including zinc sulfide, lithopone, zinc-treated titanium dioxides, and magnesium silicates, increases absorptiveness beyond that of unpigmented linseed oil films, but to a lesser degree than those inthe second class. Paint of acicular pigments swelled more (4 or 5 times) across the grain, that is the direction of last flow of liquid paint before hardening, than along the grain. -- AATA