Paint over old motor oil stains?

[John K Jordan]

Hey finishing wizards!

I bought a used portable building and want to paint inside, walls and ceiling (all insulated and paneled with osb).

The building has a pressure treated plywood floor that I'm considering painting with epoxy floor paint since I have some on hand. In several places there are oil stains on the plywood, such as I might expect if I stored a chainsaw or leaky lawnmower. There is no trace of oiliness to the touch or oil smell - it might have been from years ago.

Any ideas of what if anything I can try putting on the plywood (besides another layer of ply!) that will increase the chance of the floor paint sticking? If finishing a small piece I might try a coat of shellac, but on a floor?? Just sand and paint?

I don't care if it is beautiful. This building will be for my beekeeping stuff.

JKJ

[Mel Fulks]

The old but still on the market BIN pigmented shellac is good for preventing bleed through. The GLIDDEN Gripper primer has been reccomended here a number of times ,too; it's an acrylic . I have not yet used it as a stain blocker but it drys fast and sticks real well. There are online mentions of some using it as glue!

[Wayne Lomman]

John, give it a really good scrub with an alkaline degreaser. Rinse it well with really hot water, let it dry and you will be good to go. Open all the doors and windows to get it really dry. I don't recommend a non epoxy primer. You will still get adhesion problems due to the difference in physical strength of the epoxy compared to other coatings. Cheers

[Curt Harms]

I was wondering about driveway cleaner. The stuff I have - don't have the original bottle any longer - worked very well on oil stains in asphalt. No idea how it'd work on wood.

[John K Jordan]

Thanks.

Wayne, can you recommend an alkaline degreaser that might be available locally?

I admit until you mentioned it I didn't realize that PH was an attribute of degreasers.

JKJ

[Wayne Lomman]

John, sorry I can't recommend an actual product. Australia has quite different brands etc. The most important consideration is to avoid solvent based products. Cheers