These days, there are no simple answers when it comes to paint. Apart from the systems that provide light, heat and water, probably no single element of house construction has changed as much over the past 100 years -- and it's still changing. So when do-it-yourselfers have questions about paint, they're almost certain to be good ones.
A Baltimore reader offers a perfect example: "We have owned a 160-year-old wood clapboard house for two years, and the exterior needs a paint job," he writes. "There are multiple small areas on the shaded side of the house where the paint has peeled down to bare wood, and some areas have alligatoring. On the back of the house is a two-story addition. . . . That exterior is textured plywood . . . and the paint there is in reasonable condition.
"Do we paint with oil-based paint or latex?" he asks. A painter he consulted thinks the old part of the house is painted with oil-based paint, while the newer part may be latex.
"The way I see it," he continues, "the questions are:
"1. Do latex paints hold up as well as oil-based for exterior work?
"2. How successful will covering oil-based paint with new latex be? Will I have peeling in 1-2 years? . . . Should the old surface be completely primed before applying latex?
"3. What about the addition? Is there any way to tell if the previous paint is oil or latex? . . . Might not the danger of covering oil with latex be even greater?
". . . I suspect this is a common dilemma for many owners of older homes, and will probably become even more common as oil-based paints are phased out on a larger scale (they are not available to my father-in-law in New York state)."
The first thing to remember with any painted surface is that 50 percent to 75 percent of the job is preparation. No type of paint will stick to or stay on a surface that isn't in the best possible condition to receive it.
And even then, there may be problems. In this reader's case, "some of the surfaces are going to be questionable no matter what you put on," says Larry Horton, general manager of Budeke's Paints Inc. Alligatoring can be caused by bad surface preparation at some point in the past, or simply by the fact that the paint is old. Older structures with a lot of old paint on them are bound to have problems.
"Paint carries weight with it," Mr. Horton says, and when, over time, multiple layers are built up, sheer weight can cause cracking, peeling or flaking. The surest way to avoid problems in the future is to remove the old paint entirely -- but there are other serious problems with that approach. First, it is expensive and time-consuming -- and, with old wood, the paint may be what's keeping it intact. Repairs are bound to be needed.
The other problem is that any time you are dealing with old paint, you are almost certain to be dealing with lead. Only in recent decades has paint become free of lead, a proven health hazard. Lead paint can be removed only by certified professionals working in environmentally sound techniques.
This doesn't mean you should abandon the idea of painting the house, though that might be the first reaction. It does mean you have to be careful when doing prep work -- wearing protective clothing, and a mask that filters particulates (not just a dust mask).
The old surface needs to be clean and flat. That could mean hosing down, scraping or even pressure-washing and sanding. The more care you take with this step, the better the paint will adhere.
Mr. Horton suggests priming the entire surface of the house with a good oil-based primer. Oil-based primers assure that the house can breathe -- that is, moisture can escape to the outside. Of course, the many layers of paint, or actions by previous owners, may have eliminated the breathing room in a 160-year-old house. But oil-based primers will prepare a good, sound surface for exterior paint, Mr. Horton says.
He recommends a good, acrylic latex exterior paint for the entire house. "With the proper primer," Mr. Horton says, "the new generation of acrylics are actually doing better" than oil-based // paints in terms of durability.
Mr. Horton has a simple technique for determining what type opaint was used on an old surface. He puts a little "Goof-Off" -- a product painters use to repair small mistakes and clean up after painting -- on a cloth and rubs it into the old paint. If it's absorbed into the paint, then it's probably latex. "If you work real hard on it and it doesn't show signs of dissolving, it's probably oil-based." (He cautions not to be fooled by chalkiness rubbing off; the Goof-Off should make the surface gummy, if it's latex.)
For now, he says, he still can recommend oil-based primers, and homeowners can still buy oil-based paints. However, states like New York and California, with more stringent laws in effect to meet standards for volatile oil compounds released into the air, have been banning oil-based paints, or making them harder to find and use.
So far, laws in Maryland aren't so strict. But Mr. Horton sees the day coming when oil-based paints will disappear from paint shelves in Maryland. "It's right on our doorstep," he says. "It's coming -- I'd say, within the next couple of years."
If you have questions, tips or experiences to share about working on houses, write to us c/o HOME WORK, The Sun, 501 N.
Calvert St., Baltimore, 21278.