Wallboard First Primed, Then Painted

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 on painting?

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 calendered surface, and 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 advise 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 wallboard manufacturers and the Gypsum Assn., a trade organization that represents wallboard manufacturers, recommend a heavy-bodied latex paint as a first coat over new wallboard.

One major manufacturer, United States Gypsum, makes a base coat for new wallboard, called, appropriately enough, First Coat. It is available premixed, or it can be purchased in powder form and mixed with water. It is cheaper than ordinary primer and will provide the coverage of primers and sealers without the disadvantages of either. 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 Assn. advises professionals to shear-coat the entire surface of the wall and/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.

Troweling a complete room can be a messy job, however, if you are not skilled with a trowel, so we advise using First Coat. Once the surface differences have been eliminated, you can coat with any type of paint.

Soap and Water Work on Dirty Painted Walls

Q: Can you give me some tips on how to wash painted walls? The walls are painted with white washable paint.

A: If you are interested in just cleaning a dirty wall, you can use soap and water. A gentle liquid soap, like Ivory, is good. Rub the wall down lightly with a towel or a sponge. Don’t scrub too hard, or you will create a slight gloss by removing the pigment.

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To submit questions, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, NY 10019.