No Easy Steps For Fixing Calcimine
Sorry to say it, but I have found from personal experience that calcimine elimination or neutralization is a gritty job, and one you can not afford to shirk. So ... dealing with calcimine requires first that you know what kind of critter you are faced with. Any old house of the wood lath and plaster variety has a high probability of calcimine underlying its multiple layers of paint. This is often true of houses (USA) built in the 1930's and earlier. Turn of the century (1900) houses are especially prone, in my experience. Calcimine was widely used in those times as an inexpensive paint substitute. It is essentially a colored lime (chalk) wash with some kind of glue material and perhaps other ingredients to help it stick and make it (relatively) stable. Real plaster of those times often took months to cure properly after it was applied. No painting was to be done until it fully cured. But raw plaster needs some protection and decoration for people living in the house. The solution? Calcimine brushed over the new plaster walls and ceilings. The plaster could continue to cure and the real painting job could be postponed for months or years. But the problem is, paint put on later over the calcimine is prone to bubble or flake. Piling on additional layers of paint in the following years, while they might be pleasing to the eye, does not solve the problem of a very unreliable foundation. A calcimine infected house often has obvious symptoms. That new coat of paint may start peeling with days or weeks of application. I get a call from a disheartened homeowner. He or she can’t figure out where the water is coming from. Sometimes it IS some water intrusion at the root of the problem, but most often when we take a look at it, we discover behind the peeling paint a chalky layer. Moisten the finger and wipe it over the trouble area. Yep, it’s calcimine. So we talk solutions. Not easy fixing calcimine. There are only two realistic approaches. Remove it, or cover it up. Removal: I just did this for a customer recently, in an 1870's house. Here is the approach I took. I make no attempt to fix the whole room. The time and money it would have taken was too much for their budget. So with the homeowner’s consent, I dealt only with the immediate areas where the peeling was obvious. I attacked the bad areas with a paint scraper, just to get rid of loose paint. Then I dampened the exposed calcimine and scrubbed it vigorously with a wire brush. With repeated wetting and scrubbing, I could remove a good part of the calcimine. The rest I got off by scrubbing with a wet sponge. This required frequent changes of water in my wash bucket. I ended up with an inch of damp powder on my floor coverings. By the way, I screened off the remainder of the room and house with plastic sheets draped from the ceiling to the floor. I didn’t want any powder drifting all over the house. And, of course, I wore a dust mask and eye protection. So, now that the calcimine was fixed (removed), what comes next? I mixed up hot mud with a plaster bonding agent added and skim coated the areas I had cleaned, after first taping any plaster cracks with paper drywall tape. After the hot mud set up, I did a final skim coat of regular joint compound, which is softer and easier to sand. I let it dry overnight, returned the next day to add texture to match the rest of the room. Everything stayed tight, the homeowner primed and painted, and it turned out great. And no callback. Second approach: fixing calcimine by covering it up. No, not skim coating. The moisture from skim coat soaks through the paint and the calcimine underneath reacts by rearing up in bubbles. Cover up here means attaching thin drywall over the whole surface.
This is labor intensive, but far easier than removing all the paint layers and calcimine over a whole room. I like to use 3/8 inch rock on the ceilings, and quarter inch on the walls. I use drywall screws and go for the ceiling joists and wall studs where I can find them, and when I can’t, I can screw into the wood lath. I also like to put some glue on the backs of the sheets, just for a little more insurance. Then, it’s just a matter of taping and finishing the joints. The old house I did recently (March ‘08) was built in 1923. The old lath and plaster was in really bad shape, with everything from calcimine, old damage from water leaks, broken plaster from putting in new wiring - and some new framing thrown into the mix. The owner could have removed all the old plaster down to the lath, but he shrank from the labor and the mess. My proposal to overlay the plaster made him happy Fixing calcimine is a project, as you can see, with no simple solutions that I know of. Sometimes you get lucky, and you can paint or skim without problems. My take on this is that some calcimine products were of higher quality than others. Those with the most binder (glue) probably are more stable and more forgiving. But if the old house in question just can’t seem to keep a paint layer looking sound for long, calcimine is very likely at the root of the problem. Now that you know what to do, may the Force be with you! ___________________________________________________ |
