identify existing finish ...

Old 11-11-19, 02:39 PM
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identify existing finish ...

I did forum searches for: existing finish / finish / identification ... with no good results.

Project: Convert old dry sink into lavatory cabinet for apron front sink.

Problem #1: The finish is de-laminating. It looked like air bubbles under ice.
My first round of test found the failing finish to be a polyurethane or varnish, in as much as if was brittle and flaked off without much effort. I am assuming the old furniture shop spray coated it to make it shine for sale.

Problem #2: Finish under shiny flaking surface is not reacting to any tests.
I have gone through the commonly reported tests to identify the existing finish with no observed result.
- wax: mineral spirits ... does not react
- oil: drop of oil (linseed) ... oil it is supposed to soak in ... does not soak in
- shellac: denatured alcohol (drop and soaked cotton swab end) ... finish does not react
- polyurethane: acetone (drop and soaked cotton swab end) ... does not soften finish
- varnish: acetone (drop and soaked cotton swab end) ... does not soften finish

So I'm stumped and before I start winging it wanted to see if I could find someone else's experience would provide insight.

As stated, this is an old dry sink. I would have assumed it to have been oiled just because of its age and use. I have read that if wood is fully saturated with oil it will not soak up more. So how would I know if that is the case?

The wood is a reddish brown. More like walnut than cherry as seen from the unfinished inside. The top is a single 5/8" to 3/4" thick x 18" wide.

- What is the next step?
- If I do not know what finish is on the wood what are my choices for refinishing?
Old 11-13-19, 04:04 PM
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... what worked

Paint stripper (Citristrip) took off the shine and a majority of the red.
From other sources this would indicate that there is a penetrating sealer on the wood and in this case with color.
For what it's worth a bead of water will sit on the surface for 15 minutes and not leave a mark.

Unfortunately the stripper takes off anything ... so what the finish is, is still in question.
At this point assuming sanding to refinish is required.
I will feel better if I can find something on the market that would act like the existing finish.

Based on how water beaded and did not stain I am thinking the finish is a polyurethane or varnish but do not know why the acetone and xylene (tried that too) did not do anything to the surface. Suspect the reference for testing with acetone left something out.

Last edited by tangobaker2; 11-13-19 at 04:38 PM. Reason: additions
Old 11-13-19, 04:29 PM
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Start off by posting a picture so we can see what your seeing.
Old 11-14-19, 02:49 AM
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Paint and varnish remover should remove most of the existing finish although stain is the most difficult to remove. The more caustic strippers are more effective than citrus based strippers. I've never tried to strip and oil finish and not sure what would be the best method for that. I assume this is solid wood and not a veneer ??

As Joe said, pics could be helpful - How to insert pictures.

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