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Thread: Problem Finishing Mahogany

  1. #1

    Problem Finishing Mahogany

    I am in the process of refinishing 3 older mahagony tables and I am having problems with the tops. I have stripped the old finishes carefully and have sanded the bare wood thoroughly using a random orbit sander and sandpaper grits of 60-80-120-220 progressively.

    When I applied the first coat of Minwax oil-based stain, I noticed dozens of pea-sized "craters" where the stain was not being uniformly absorbed. Same with the second coat of stain as well as with the three coats of Minwax clear satin polyurethane. On one top, I even went to 7 or 8 coats of polyurethane and the "craters" were still visible.

    Any ideas as to what the issue is here? I work in an unairconditioned area that sometimes gets a bit humid, but I've been in the same workshop for 5 years and this has never happened before!?! Help!

    Bob Rifenberick

  2. #2
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    Could it be that some wax that was applied to the table, over the years, got through to the wood from cracks in the old finish?

    Maybe rubbing the wood down with some sort of thinner first would help?

    Sorry, all I can offer, I've not had this problem.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  3. #3
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    ask dave hawksford, that is his specailty refinishing old furniture!!!
    If in Doubt, Build it Stout!
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    Don't put off today till tomorrow!

  4. #4
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    you'll have that with mahogany.
    Oil is not a good product for Mahogany. I'd use a water stain then wipe or spray on 2 -3 coats of shellac to seal

    Fish eye are what we call the little craters you are seeing. Causes; air trapped in the grain , partials of ? trapped in the grain.

    Did you strip the tables of just sand them. Over the years cleaners , silicone in particular will get into the oil finish and when stripping will seep into the grain also. I usually wash a Mahogany table down with lacquer thinner and then with the air hose blow out all the edges [end grain pieces] you will be surprised where some of the grain tunnels will spew moisture.

  5. #5
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    Quote Originally Posted by Dave Hawksford View Post
    you'll have that with mahogany.
    Great info Dave. Do you find this with mahogany that has never been finished?
    Any sufficiently advanced technology is indistinguishable from magic.
    - Arthur C. Clarke

  6. #6
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    I rarely do new mahogany and when I do I always seal with shellac to avoid any problems, after the shellac I will spray Lacquer sealer and finish. But Shellac is to seal in the tonic ? acid for new untreated wood.

    For refinishing Mahogany alot of times after we strip and clean with lacquer thinner so not to raise the grain we will sand with 220 seal and then 320 before finish. By not having to sand with higher grit we avoid opening the wood up to releasing the tonic acid which also is a culprit for fish eyes.

    Mahogany is a strange wood, my least favorite next to pine. It is also poisonous and everyone should ware a dust mask when sanding it.

  7. #7
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    Dave,

    Great info, thanks for sharing.

  8. #8
    What you discribe is "Fish Eye", Usually caused by Silicone contamidation. When you sanded the top you rubbed in the culpret. Go to your local Auto paint store and get some Fish Eye Eliminator and add it to som Lacquer, Resand the top, careful; not to use the same discs, or rags, or anything that may have contacted the silicone. Spray on a coat of the Eliminator enriched Lacquer (or brush) then apply top coat with your favorite finish. this should solve the problem.

  9. #9
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    "Go to your local Auto paint store and get some Fish Eye Eliminator and add it to some Lacquer"

    most fisheye killers will have sillicone in it and will get it your pumps, hoses, and guns or whatever fluid passage ways you have and will be a problem on your next work. try to keep it out of your equipment, trust me. and anything you put on top will also need to have the fish eye killer in it.

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