I have a wartime house and at some point the cement foundation blocks that are above ground were painted. I have owned the house for 16 years, so it was at least 17 years ago, but probably more like 25. I bought the house from a couple in their late 80's and the living room wallpaper was a scene of a golf course (circa 1960 something). Anyway, the paint is starting to peel and chip from the cold and snow. Should I paint it again and if so with what kind of paint?
When our Florida condo was painted, the contractor used acryllic latex paint, which is standard for masonry. The pressure washed below grade about six or eight inches so as mortar absorbed moisture beneath the new paint coat, it would be buried and not show peeling. They applied a bleach solution prior to p.w., which didn't make a lot of sense, but the job turned out wonderfully and lasted. For hairline cracks, they used a brushable caulk, then one coat primer and one coat paint. They had rec. two coats paint, but condo went for lower cost and the results could not have been better. The previous paint job was poorly done, with loads of mildew (no prep) under the peeling paint.
I used a wire brush on a electric drill to remove loose paint on my moms house before I sold it. I drive by that home the paint looks great after at least 10 years...
I'm not saying the OP's concrete blocks were painted in the 50's or
60's.
I'm saying that the practice of cleaning walls with TSP was good advice back in the 50's and 60's when it could be reasonably well assumed that the paint on every wall was a linseed oil based paint. TSP would etch the gloss of drying oils like linseed oil, Tung oil and real varnishes so that a new coat of paint or varnish would adhere better.
The problem is that paint is the least well understood technology in the entire Home Depot store. So, even though paint technology has changed immensely over the past 50 years, people's knowledge of paint hasn't kept up with those changes, so you still find that same advice to clean with TSP being given today.
Don't get me wrong. If someone is wanting to paint over an old linseed oil based paint, then the advice to clean with TSP first is good advice.
But, if they're wanting to paint over anything else, like an alkyd paint, a polyurethane paint or a latex paint, then cleaning with TSP won't etch the gloss of the paint. In fact, it won't do anything at all to the old paint. In that case, the person would be better off using a good quality detergent like Mr. Clean or Fantastik to clean with. That way they'll be removing both dirt that's soluble in water as well as oily dirt that can be emulsified by the detergent, like cooking oil if the person is painting a kitchen ceiling, or fingerprints around light switches and on the walls near the front and back entrances.
It's this misunderstanding about TSP that creates misinformation about it. People reason that if the advice is to clean with TSP, there has to be a good reason to do it, and so they make up reasons that make sense to them. Some people say TSP is a good "degreaser", which is total misinformation. I once tried cleaning an old greasy stove with TSP and it didn't do anything at all to the grease. It's that logic that there HAS TO BE a reason to clean with TSP that creates misinformation about what TSP does. Everything becomes clear once one realizes that there is no reason to clean with TSP unless one is cleaning a drying oil film like linseed oil based paint, Tung Oil or real varnishes before repainting or revarnishing.
| Some people say TSP is a good "degreaser", which is total | misinformation.
You seem to have very strong feelings about TSP, for some reason. It may not be fair to blame it for all past misconceptions that anyone has had. :)
It's not a degreaser, but it will dissolve oils, like skin oil left on woodwork, which can inhibit paint bonding. It's mainly a very good surfactant that will easily wipe away the black grime that collects on woodwork over time. TSP was used at one time in laundry detergent.
The purpose is not to "etch" the old finish. The purpose is to clean residues off painted surfaces without leaving a soap film. But cleaning with TSP requires hot water. Maybe you've used it with cold water or lukewarm water? If you use it with very hot water (and you should wear gloves because it's a strong alkali) it's a very aggressive cleaner.
If I couldn't get TSP for paint prep I'd use non-sudsing ammonia. I *would not* use anything like Mr. Clean that sudses.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.