Thread: Removing oil stains from ply?

There's a few ways to remove oil, but the only reason to get terribly annal about any attempt, is if you plan on a bright finish. If the area will be eventually painted, then any staining isn't a problem.

Give the area an acetone bath, scrubbing as you go. The oil will break down and much of it will come out as the acetone flashes off. Use paper towels to mob up, before the acetone flashes is more effective.

Heat will help a little as will water (oil floats), but mostly you just need a clean surface, which can be had with an acetone scrub. Epoxy will still penetrate into the surface, grab the wooden cells and cure, with a little oil on it. Plain old dish detergent works good to remove oils, so this would be my first move, saturate the area with water and dish detergent, scrub good and mop up with paper towels. Dry the area and move onto the acetone, if you think you need it.

Thanks a bunch PAR, the two 3inch diameter stains are gone. I don't think they soaked in as much as I first thought. I really wanted to epoxy today so I stayed away from the detergent approach and went the acetone route first, giving it a soak and scrub, wipe, heat gun wipe again. I did it twice and it did clear the stains up really well except a very slight hue remained. I had to sand the hull all over to prep it and with a quick hit of 120grit on the random orbital the remaining hue from the stain disappeared. No more material was removed from those spots compared to anywhere else on the hull. Only light sanding.

I'm not doing a bright finish and have in fact laminated another sheet of ply over the bottom of the hull to strengthen it. But I wet out the area first and as the epoxy covered the area I couldn't tell where the oil was. I was happy to see the result and pretty confident a bright finish would be possible. Good to know for the future.

Cool deal. Good to hear you've had success. The dish detergent trick works pretty well on heavy stains, so you can come back and get the rest with acetone, but light stains, like yours should (did) come out pretty easily. You have to remember, on plywood with a WBP glue, the oil can only penetrate as far as the glue line on the outer veneer, so you don't have much wood to really clean. Glad it worked . . . Time for pictures isn't it . . .

Hehe, yes. I suppose a few pics are in order. I hadn't planned any for this thread but I have been taking a few for a planned refurb thread. Unfortunately, there are none of the cleaned area after acetone and sanding treatment. Once cleaned I used thickened epoxy to fill gouge marks in the hull that occurred during the stripping process. By the time I thought about taking photos I didn't want to get epoxy on my phone and the area was wet out then thickened epoxy added on top before it cured. I should've used gloves to keep my hands clean because comparison photos would've looked great.

One more thing, what a good point regarding the glue line, I never thought of that. I had visions of oil working its way through to the interior and delaminating the ply and reverse side epoxy.

Here's the offending oil stains



Here's where we're at now. Hull was sanded, gouges filled and hull faired again and another lamination added to the bottom panel. You may remember I tried build this on the cheap with products from a local major hardware store. The hull was from CD bracing ply which is really not suitable. The bottom is weak and too flexible. I had issues with epoxy cracking, partly due to being too thick. I've laminated a second piece of ply to the bottom now, this ply being again,4mm brace ply, but is a CC finish with A bond ply and so much better, stronger and more uniform than the original, but it aint no marine ply either. Just removing staples now but the strength is incredible with barely any flex resting my elbows in the middle. I had previously added FG tape to the chines and repaired cracked epoxy on panels with tape prior to painting but will cover the lot with FG cloth to add strength to the other panels. I'll add more details in another thread soon.

Originally Posted by Canoath

. . . I thought about taking photos I didn't want to get epoxy on my phone and the area was wet out then thickened epoxy . . .

You're not a boatbuilder, unless your phone has a big scratch on the screen, from a chisel that shared the same pocket and at least a smear of cured epoxy on it some place.