Applying epoxy to oil stained wood

Discussion in 'Boatbuilding' started by mariobrothers88, Jan 31, 2021.

  1. mariobrothers88
    Joined: Sep 2020
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    mariobrothers88 Senior Member

    Hi guys this is actually unrelated to my boat building project but I have a piece of wood that has been stained with a 50:50 combination of motor oil and diesel. I decided I want to add an epoxy coat over it. I'm debating between two options :

    1. Coat it with a latex (Polyurethane) paint then apply 2 coats of epoxy.

    2. Seal it with 1-2 layers of zinser seal coat and then apply a couple coats of epoxy. If I decide to apply the zinser seal coat, how many coats do you guys recommend and do I need to sand the zinser seal coat before applying epoxy?

    Thanks in advance I appreciate any and all advice!!
     
  2. ondarvr
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    ondarvr Senior Member

    Not much sticks to motor oil and diesel.

    Epoxy is used as the first coat because it bonds so well, putting over anything else sort of defeats the purpose.

    If the concoction was applied a long time ago, it may have dried out enough to get better bond though.
     
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  3. mariobrothers88
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    mariobrothers88 Senior Member

    Thanks for the advice! It was applied about 7 weeks ago and it was brushed on. Ive read that Polyurethane and zinser seal coat would bond well to oil stained wood and then epoxy should bond well to the Polyurethane and zinser, would you guys agree with that?

     
  4. gonzo
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    gonzo Senior Member

    You are talking about oil soaked wood. In general, oil stained refers to linseed or tung oil based stains that dry off or harden. What you have won't let any hard coating adhere. It is possible to degrease the surface, and a bit below it, with a hot solution of lye or other harsh commercial cleaner. However, it is very likely that the oil will migrate to the surface and blister whatever coating you put on it.
     
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  5. bajansailor
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    bajansailor Marine Surveyor

    Maybe I am missing something here, but it begs a question - is it feasible to simply replace the piece of wood with a new piece that is not oil stained?

    What is it used for, how large is it, etc - would it be difficult to replace?
     
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  6. mariobrothers88
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    mariobrothers88 Senior Member

    Hey guys this is for a wood railing for a patio of an oceanfront home in rosarito. I initially thought I can just coat it with motor oil/diesel so I don't get wood rot. I had a carpenter friend who told me due to the oceanfront location the motor oil/diesel would be insufficient due to the high humidity of the oceanfront location and he said I should sand it and add a couple layers of epoxy. Another person told me that I don't need epoxy and the oil /diesel is sufficient to prevent water and wood rot. What do you guys think? We don't get much rain here maybe like 10 days a year of rain.
     
  7. bajansailor
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    bajansailor Marine Surveyor

    Thanks for this clarification.
    What does the railing look like - is it pleasing to the eye, or does the oil and diesel soaked into it not look very nice?
    Maybe your best solution in the given circumstances now might be to simply add more oil - but 'proper' wood oil this time (definitely not engine oil!).

    Re epoxy resin, even if you could clean it sufficiently as per Gonzo's suggestion, and assuming that residual oil does not subsequently lift the epoxy, you would still have to protect the epoxy with something re the sun's UV rays (which are pretty intense in San Diego).
    If you don't protect the epoxy from the sun (eg with a few coats of varnish, and then regularly re-apply additional coats), it will probably only last a few months before it starts blistering / cracking.
     
  8. gonzo
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    gonzo Senior Member

    Basically, you are screwed. Either leave the oil soaked wood and never lean on it or touch it, or replace it. Engine oil will get on your clothes and body whenever you touch it.
     
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  9. mariobrothers88
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    mariobrothers88 Senior Member

    Thanks for the advice!

    I can touch it now and it doesn't get on anything. My only concern is with wood rot and degradation of the wood. Cosmetically it is acceptable. Do you guys think I will eventually get wood rot if I just leave it with the motor oil and diesel?
     
  10. gonzo
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    gonzo Senior Member

    Eventually is a long time. What type of wood is it?
     
  11. ondarvr
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    ondarvr Senior Member

    Most protective coatings on a railing like that eventually fail, I'm talking about epoxies' polyurethanes and the like.

    And like mentioned, epoxies need protection themselves.

    At this point I would probably leave it as is, then reapply your blend, or something similar every year, or as needed.

    It won't rot if it's soaked with oil.
     
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  12. Rumars
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    Rumars Senior Member

    A railing in rosarito? Even if constructed with crap lumber and without any knowledge it should last 20-30 years without any coating at all. The biggest threat to it are termites, not rot.
    What did you make it from?
     
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  13. mariobrothers88
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    mariobrothers88 Senior Member

    Pine

    Thanks everyone for all the great advice!!
     

  14. Rumars
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    Rumars Senior Member

    Pine is chocolate ice cream for termites, it will not last long enough to rot. Next time, redwood, WRC, AYC, etc., and make sure you buy heartwood.
     
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