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'm not saying the OP's concrete blocks were painted in the 50's or
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
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
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
Scrape and wire brush any loose paint. Wash any areas to be painted
with a detergent. I've used laundry detergent with a scrub brush on a
short pole. It works as well as anything else. The brush on the pole
saves a lot of bending. Rinse with a hose. After drying, spot prime
any bare areas with a solid coat of an exterior rated acrylic primer.
Top coat with a quality exterior paint in the finish of your choice.
My preference is flat or low luster.
On Mon, 11 Aug 2014 03:44:02 +0000, Lili Marlene
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