Question: I have just finished renovating my living room and am now at the stage where the wallboard work is completed. Can you give me some advice as far as painting is concerned?
Answer: Decorating newly finished wallboard can present a challenge for the amateur, because wallboard presents a problem surface for the painter. When painting wallboard you are actually painting two materials: the paper covering of the wallboard, and the compound that was used to treat nail or screw heads, seams and corners. The paper face has a slightly rough or "calendared" surface, while the taping compound is glass-smooth. These two surfaces also present unequal absorption rates, and will soak up paint or primer unequally.
Because of these problems, wallboard manufacturers have always advised that you use a latex or water-based primer as a first coat on a new wallboard. Oil primers may dry slowly, soak into the paper face of the panels, and cause the paper nap to raise. Oil primers on wallboard will often cause very smooth spots where there is compound over seams or fasteners, and very tough areas where the nap of the paper has been raised. Thus, all wallboard manufacturers and the Gypsum Association, a trade organization that represents all wallboard manufacturers, recommend a heavy-bodied latex paint as a first coat over new wallboard.
One major manufacturer, United States Gypsum, makes a special base coat for new wallboard, called, appropriately enough, First Coat. It is available premixed, or you can buy the primer in powder form and mix it with water. It is cheaper than ordinary primer, and will provide the coverage of primers and sealers, without the disadvantages of either of these two paint products. First Coat will seal the surface, and contains enough fillers to act as a primer, so it equalizes the suction on both the taping compound areas and the bare paper areas.
The Gypsum Association advises professionals to shear coat the entire surface of the wall or ceiling with compound, so no bare paper is left. In effect, one just plasters the entire surface with painting compound, so there is no difference in texture between paper and compound. We advise using First Coat as a wallboard undercoater.
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