Carl Finch on tue 2 nov 04
Here is a detailed description of 2-part epoxy application posted by some
generous soul to the alt.home.repair news group last February:
I've lurked and learned from this newsgroup so want to give back by relaying
my experience and tips after epoxying my garage floor.
I epoxied my garage floor with Benjamin Moore's Industrial Maintenance
Coatings, 2-part epoxy, M36/M39 Polyamide Epoxy Gloss Coating .
The results were spectacular in terms of finish and I have had no hot-tire
lifting at all. Most dirt just sweeps off. Oils just come up with a paper
towel. This is impressive given that I had a previous 'paint' (supposedly
some new type of epoxy) done by a contractor. Not only did it lift under
car tires, it lifted under a bicycle tire!
Here is what I did and learned.
1. Prep is critical, as all the brochures say. While my prior coating came
up easily in some places, it did not in others. I ended up renting a Hilti
hand-held grinder-vac at Sunbelt Rental and grinding the entire floor. It's
a hands-and-knees job, and time consuming, but it took me down to bare
concrete and also removed some of the bumps and splotches from a lousy
concrete job. Wear knee pads and ear protection. I actually used the small
foam ear plugs underneath a noise-attenuating headset. And wear eye
protection because of the concrete dust thrown by the grinder.
My hope for your sake is that you don't have any prior paint and don't
have to go through a similar grinding step.
2. Then I washed with TSP and rinsed several times.
3. Then came the muriatic acid etch. It's not as scary as you'd think;
just follow the directions.
But here's a TIP for an issue that I've not seen described anywhere.
Move all iron and steel things out of the garage. If you can't do that wrap
them in plastic. Even the fumes of the muriatic acid makes steel rust very
badly. Tools I had hanging on the wall were covered with rust the following
The second part of the wash with muriatic acid is to neutralize it with
a solution of baking soda. For the concentration mixtures of the acid and
baking soda solution follow instructions provided with the muriatic acid, or
seek someone with experience in a paint store.
3. Then let it dry several days. Use the trick of taping a piece of
plastic over a couple square feet of floor overnight. If it's completely
dry in the morning the floor is probably dry enough. (If water never ceases
to appear under the plastic you've got a water source coming up through the
concrete. If so, paint or epoxy are not going to work, so hang it up.)
4. Then I thought the floor was sufficiently prepared as I was down to bare
concrete everywhere. I was wrong. The test of adequately clean concrete is
to put a drop of water on the surface. It should quickly spread out and be
absorbed. In my several tests I did the water drops penetrated instantly.
A day later I buy the epoxy (which I had tinted). I got home and did the
water drop test again for no reason other than that it made me feel great to
see the water drops instantly penetrate the concrete, given the horrible
condition of the floor I started with. I tapped a few drops on and suddenly
one of them just sat there on the surface. Panic! I then proceeded to get
on my hands and knees and do the droplet test every couple of inches over
the entire garage floor. More places where it didn't absorb, and I put
pieces of sticky notes in each location. When I was done the sticky notes
mapped out areas corresponding almost exactly to where the car tires rest.
In those places water did not absorb. This was shocking because not only
did the concrete look like knew I had ground off the surface with the
grinder. It appears that the petroleum products that are either in the
tires or are picked up from the roads are then pressed onto the concrete and
absorbed. I subsequently did research and read in places that oils and
paints may penetrate to as deep as 3/4 inch in some circumstances.
So I ground those places deeper with little effect but I wasn't about to
grind 3/4 of an inch because then I'd have to patch with concrete, and if I
did that I'd have to wait about 90 days (as I recall) for curing before
applying the epoxy. Finally, not knowing what else to try, I got some
garage floor degreaser at Home Depot and treated those tire areas several
times, as per the label, scrubbing, rinsing well, etc. After several
degreasing cycles the water drops would absorb somewhat in those areas. Not
as well as in all the non-tire areas, but much better than before. For
example, a drop might appear to sit there for 2 seconds, then slowly spread
out and be absorbed. Believing I couldn't improve it further and not really
having any alternatives, I moved on.
[But before doing so, I did another muriatic acid etch (with a higher
concentration) and a baking soda rinse in those areas I had degreased. Then
I waited a few days again for it to dry.]
5. Now time to epoxy. As I said, I used Benjamin Moore's M36+M39. The
paint store may give you 'local wisdom', or experience, or vague guesses.
If you want to double check, Benjamin Moore has corporate technical support
people whom you can call about these products. As it turns out, the owner
of my local Benjamin Moore store had a lot of experience with the product
and was a good source, whereas his employees were not.
You need to know that 2 coats are really recommended to give a good finish.
You may not find this out if you don't talk to the right people, so here's
another tip. As it turns out, the pigment particles in colored epoxies are
larger than the solvent molecules. Epoxy is a strong finish because it
penetrates the crevices (which were caused by the muriatic acid etch) and
when it hardens it 'hooks' into the crevices, which is why it adheres so
well and doesn't lift. But if the penetration into the crevices is impeded,
the epoxy doesn't grab as well so is more likely to lift off. And the
pigment impedes the penetration.
So the officially recommended course is to use a pigment-free first coat.
However, 2 color coats are necessary to give a good finish, so know you'd be
talking about 3 applications (one 'primer' and two color coats) which means
more work and expense.
TIP: You can save one coat by skipping the 'primer' coat and thinning the
1st color coat with epoxy thinner (xylene). [Benjamin Moore sells epoxy
thinner as M95, but I'm pretty sure it's nothing more than straight xylene.]
This is what the owner of the Benjamin Moore store told me. I called the
B/M tech support line and they wouldn't recommend it and said the proper
procedure was the separate 'primer' coat. I went back to the B/M store and
talked to the owner who said that new federal regulations to control
volatile organic compounds (VOCs) don't allow B/M to endorse thinning with
xylene, but that doing so would work just as well as a separate 'primer'
coat. Then I called tech support who admitted they couldn't say much
because of the VOC regulations. So I asked: "If I had come to you before
the VOC regulations and had said that I wanted to thin the first pigmented
coat with xylene and asked you if that would be just as good as using a
separate primer coat would you have said yes?" He said that he would have
said yes. So I got my answer and he remained legal.
My recollection is that I thinned with 1 quart of epoxy thinner (xylene) for
each 2 gallons of epoxy (1 gal of M36 + 1 gal of M39), but I suggest you
check with your paint store.
6. The first application. The obvious means of applying it is rolling it
on, however you can also squeegee it on, which is what I did. The advantage
of using a squeegee is that if you have pits and holes in the concrete
surface you can more nearly fill those with the squeegee than with a roller.
It's fairly easy, but with a fairly smooth concrete surface a roller would
Another tip: There is a range of recommended thickness for each coat,
but how do you know you're applying to that thickness and not too thin, or
too thick (which would have the added risk of running out)? I basically
marked out areas along one wall with sticky notes every 4 feet, and along a
perpendicular wall every 5 feet, allowing me to estimate 5'x4' sections, or
20 sq ft. I don't remember the recommended coverage for the 2 mixed
gallons, but let's say for example it should cover 600 square feet. So I
have 2 gallons, or 256 ounces to cover 30 20-sq.ft. sections. So, if I
apply 8 ounces per 4'x5' section I'd use 240 ounces, with just 16 ounces
left over -- pretty close to the exact recommended coverage. (I
intentionally neglected to account for 32 ounces of thinner in the first
coat, as I didn't know if it would add exactly that much volume, and I
wanted to be conservative so I didn't run out.) Anyway, you get the idea.
Do the math to your particular situation.
Then I scooped 8 ounces in a glass cup and drizzled it around each 4'x5'
section and then squeegeed it to cover. (Or in the case of the 2nd coat,
rolled it to cover.) Use a glass cup because xylene eats through plastic.
7. Second coat. It should be ready for a second coat the next day. I
waited until the 2nd day for the second coat. This one I rolled on. I did
not add particulate matter to create an anti-skid surface. I live in the
south where snow and ice are not an issue. Slight wetness hasn't caused a
problem, thought I can see that if you had standing water with smooth-soled
shoes it might be. The downside of sand or some other anti-skid material is
the high points will show wear sooner as the epoxy is abraided from the
points of the sand.
That's it. Wake up the morning after your second coat and go be stunned by
your great garage floor.
Now I feel like I've given something back. I hope this helps someone.
in Medford, Oregon