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.
- 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.
- Then I washed with TSP and rinsed several times.
- 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 day. 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.
- 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.)
- 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.]
- 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.
- 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 be faster. 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
- 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.