desired to enhance air drying suitable drying oil fatty acids may be used and include those derived from linseed oil soya bean oil tall oil dehydrated castor oil or tung oil polyurethane polymers containing terminal isocyanate or hydroxyl groups may also be used the polyurethane polyols or nco terminated polyurethanes which can be used include those prepared by reacting polyols including polymeric polyols with polyisocyanates the polyurea containing terminal isocyanate or primary or secondary amine groups which can be used include those prepared by reacting polyamines including polymeric polyamines with polyisocyanates the hydroxyl isocyanate or amine isocyanate equivalent ratio is adjusted and reaction conditions selected to obtain the desired terminal group examples of suitable polyisocyanates include those described in u s pat no 4 046 729 at column 5 line 26 to column 6 line 28 hereby incorporated by reference examples of suitable polyols include those described in u s pat no 4 046 729 at column 7 line 52 to column 10 line 35 hereby incorporated by reference examples of suitable polyamines include those described in u s pat no 4 046 729 at column 6 line 61 to column 7 line 32 and in u s pat no 3 799 854.