Question:
come spring, i'll have to repaint my garage floor again. parts are in
excellent shape, the rest is peeling and flaking. normally i use a
combination of leaf blower, hose and putty knife to get up the loose paint,
but this time the bad area is too large to ensure that i'll get to it all.
i've never used any chemicals (tsp, etching acid) to prepare the surface.
given when im done with my hand prep, i'll be left with (1) good painted
areas; (2) areas with some good and some bare spots; (3) raw concrete; &
(4) areas i've overlooked (they probably look good, but aren't).
question: what type of chemical treatment should i use on the floor and
should i apply it globally, or just to the problem areas that i can visibly
locate?
Answer:
If I read this correctly, it sounds as if you are re-painting the
garage floor fairly often. This failure of paint adhesion to concrete
garage floors is usually due to improper concrete preparation. The
paint adhesion is virtually guaranteed to fail in a relatively short
timeframe if no preparation chemicals are used. What type of floor
paint are you using: Latex, alkyd, polyurethane, epoxy?
I have painted numerous garage floors, and given the amount of effort
required (and not wanting to do it again), follow several guidelines
very closely: (this has also worked well on floors that were used for
10 years before being painted) The preparation is about 80% of the
work. (this preparation is for xylene-solvent 2-part epoxy)
1). scrape all surface grease, blot up all oil
2). Clean floor with industrial-strength concrete floor cleaner
3). Etch floor with phosphoric acid, keepin a good 'wet edge',
and flooding as needed
4). Thoroughly wash floor
5). Let dry for 48 hours, depending on humidity
6). Apply first coat. Working times vary, but usually range
from 90 minutes to 4 hours
7). Let cure (can range from 24 hours to 4 days)
8). 2nd coat
9). Cure.
It is a lot of work, but the floors will look great for decades.
From my (amateur) experience, my subjective rating of durability and
longevity is:
1). latex (shortest-lived)
2). alkyd
3). water-based epoxy
4). organic-solvent based epoxy (I prefer these)
5). specialty coatings (Best by far, but difficult)
Organics require and organic respirator to apply. Speciatly coatings
can require forced-respiration. I try to use the highest-ranked paint
that I feel comfortable with.
In your case, the quickest solution is to scrape, chemically treat the
exposed areas, and re-paint.If it were my garage, I'd sand-blast the
floor (which replaces steps 1 through 3), and then follow
the steps above.
