Paint-stained concrete

 I have a concrete patio slab measuring 12' x 25'.  Over 40-years, I've
used muriatic acid three or four times to clean the concrete.

About 6 months ago, oil-based paint was spilled in various areas on
the slab.  I've tried removing the stains with muriatic acid and other
products (a solution of soap-and-hot-water; paint-remover; Ajax;
bleach, etc) but nothing removes the stains.  What else can I try?

If the stains don't come out, can I paint the slab?  (The slab has a
few hairline cracks).  How do I prepare the slab, what kind of paint
should I use, and how would I apply the paint?

(I live in Riverside California (about 60 miles east of Los Angeles).
The lowest temperature may be below 15 degrees and the highest
temperature may be almost 120 degrees).

 
What disolves oil paint. Lacquer thinner and mineral spirits. You
can mix them together. You can also try the other hard stuff like
MEK and Toluene. Add some acetone and you got paint remover.

Another thought is some kind of abrasive pads on a machine.
Some kind of primer should make it easier to paint.

Do this at the coolest part of the day, preferably dark.

greg

 (GregS) wrote:


Mineral spirits is used to thin oil paint, and clean brushes, while the paint
is still wet. It does absolutely nothing to oil paint that has already dried.

Lacquer thinner is *already* a mixture of MEK, toluene, and acetone (among
other things), so there's hardly any point in adding them.

If you want paint remover that *works* you need one that contains methlyene
chloride.

 Miller) wrote:

Mineral spirits is a slow drying base. When you disolve with lacquer thinner
and the lacquer thinner evaporates, the mineral spirits is left helping
to keep the pain WET so you can wipe it away. Thats why I say
add mineral spirits.

Thats why I sometimes say clean with WD-40 because the fast evaporating mineral
spirits dries and the oil remains, and keeps dirt, paint, etc., in solotion.
I did not suggest using WD-40 to remove paint, but will remove fresh paint.


I never knew the composition of lacquer thinner. Thanks for bringing that out.
I need to read up on that. The only thing I know about lacquer is paint, doing
several cars,
something about bugs, and something about the paint drying from the inside out.


I had a shoe stain on my pants and while I did say add, some things come off
better
with pure MEK, Toluene, etc.

 (GregS) wrote:

Yes, but lacquer thinner is at best a mediocre solvent for dried oil-based
paint. A paint stripper containing methlyene chloride works far, far better.