I need to paint my front porch, but there is a small stain that appears to be oil, grease, or a similar substance. (Water beads on it, despite there being no paint or finish.) Here's the stain in context:

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And here is a tight zoom on just the stain itself: enter image description here

How does this affect the prep or the painting?

2 Answers 2


Mix a box of baking soda or sawdust with mineral spirits or isopropyl alcohol to the consistency of toothpaste and rub it in with a soft brush, leave for an hour and then hose off. Preheating the wood with a hair drier or as if in the sun to allow oil to flow easier , then reapply , If the stain persists repeat.


I'd use an oil/floor dry product (clay or diatomaceous earth) for a day or two. Standard cat litter would also work in a pinch. This should pull most of it out.

You'll want to prime the raw wood anyway, so use a good quality bonding primer to ensure good adhesion.

  • 1
    Grinding and pulverizing the kitty litter into the stain with a twist of your boot will help get the particles down to maximize surface contact.
    – spuck
    Oct 2, 2019 at 21:11

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