De-greasing motor oil / prep

[break80]

I have a couple small areas where some motor oil leaked thru a cardboard box. the overall area where the spots are is maybe 5 sq feet. I have de-greased and scrubbed it twice and there is still visible "oil stains", but the surface doesn't feel bad.

My question is, when I get ready to start with the acid etch from my Epoxy Coat kit, will that take care of any concerns with this area? Do I need to do more? The rest of my 3 car garage is pretty much ready to go. Could I buy a really rough grit sandpaper and touch up the area with a palm sander?

Thanks,

 

[munkey]

There is a fairly common misconception around here (at least, from people inexperienced with prepping floors for coating) that acid etching will remove contaminants, old coatings, etc. The purpose of using acid is to dissolve some of the concrete, thus leaving it with a rougher profile and increasing the ability of the new coating to mechanically grip the floor. But, you really need to be in good shape as far as old oil, paint, dirt, debris, etc. because the acid is not a cleaner or detergent. The acid is also not going to effective at displacing contaminants, which means that the oily area is not going to receive the benefits of the etching procedure. (Plus, since you're going to have to power wash after the acid to remove any residue, you might as well do the cleaning step first so that you can be completely finished with prep after rinsing the acid away.)

I know this is not a tremendously helpful answer because I'm not sure what the best way is to remove your oil stains, but there have been numerous posts about materials (kitty litter?) and cleaners that you can leave on the stain to absorb most of the oil. I'm sure somebody can chime in with a more specific recommendation.

 

[break80]

thanks. it does help to clarify what the acid does and does not do. I did do kitty litter first. picked up everything I couldn't wipe up, have used a de-greaser and really scrubbed it in good with a wire brush, and now there is only the set-in light stains of the oil left. I also tried a disc braker cleaner spray solvent and that seemed to take away some of the stain. I guess I'll sprinkle some water over said area and some on a section that does not have a stain and then compare what they look like

 

[AlphaGarage]

The goal isn't to completely eliminate the visible stain, that's what the coating will do.

You just need to prep the floor enough that the epoxy can adhere to it. The water sprinkle test is the best gauge, if it absorbs as evenly and rapidly on the stained areas as it does on unstained areas, then you should be good to go.

 

[LegacyIndustrial]

Acid has no effect on oil. Try a citrus based degreaser and elbow grease.

 

[break80]

thanks all. I do have a citrus based degreaser. Gonna do 1 more round of heavy elbow grease. water test, and then the prep and then will be applying my Denver Bronco themed Epoxy-Coat floor..I will do some before and after pics, cause we all know you have to have pics stay tuned.

 

[Edger]

You should be OK with your process.

The correct procedure is to soak, not scrub the oil stain with a quality degreaser. A solvent such as the spray you used would be a good first move to leach out some, then a soak with the citrus based cleaner neat for 30 mins, then wash off.

Next is acid etch and while rinsing the etch make sure that water is absorbed. You would be OK to epoxy coat the floor as soon as it is dry enough. If the water beads then you must apply more citrus for 30 mins with a light agitate during that time and do two rinses afterwards of the area - it is critical that you do not leave detergent residue anywhere. They can be either light agitate with rinse water and **** up with wet vac or mop up or power wash off. If you use a mop make sure you have two very clean mops in separate water for the two mopping rinse stages. Epoxy coat as soon as it looks dry in that area.

The trick is to remove the oil by soaking with a suitable detergent, rinse etc., acid etch, soak again if necessary, rinse thoroughly, dry and coat with epoxy before the oil soaks back up to the surface again. You will only be able to remove the oil from the top 1/64 inch if that, but that is enough for the epoxy to adhere strongly.

The only time you should have problems is when it is very hot (30C or 85F upwards) when the oil might soak back up to the surface quickly. Under those conditions we used to clean the entire floor and the next day spot the stains again 1 hr before coating.

 

[break80]

thanks. again everyone has been extremely helpful. I did the citrus degreaser last night and then I put some kitty litter on and will sweep it up tonight when I get home. Maybe it will pick up a little extra oil that may seep up. It's supposed to be 85 in Denver today ( humidity probably still super low at ~10%). This potential problem area is in a corner of the 3rd bay by the garage door. If I need to, I could put a 2nd coat of the epoxy on this area if I have any leftover.

 

[djjsr]

I use lacquer thinner. It'll dry it up pretty quickly. (no smoking or open flames)

 

[Edger]

Lacquer thinner with kitty litter, wipe or sweep off, followed by citrus soak, clean, rinse, & rinse again.

To be honest, it does not sound like a big problem. The big ones are where a machine has sat there leaking oil for years. You can only remove the top and it creeps up quickly because underneath is saturated.

 

[LegacyIndustrial]

Agreed. There is a floor on our blog that looked looked suspect when the customer approached us. Down over a year now and the guy uses it big time. All little oil spots, drip here, drip there.

Link: http://legacyindustrial.blogspot.com/2011/10/legacy-industrial-garage-floor-coatings.html