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Oily something on tabletop

1K views 4 replies 4 participants last post by  BrownTown 
#1 · (Edited by Moderator)
Hello,

First timer to the forums here, so please direct me in the proper etiquette in any way necessary.

I'm currently at the stage of finishing a tabletop composed of red oak for which I am being paid. I am going to be using General Finishes water based wood stain in antique oak, which I have used on past tables with great success. I am a garage worker so I use whatever materials are available. In this case I used some washed and reused shop rags (courtesy of the golf course I used to work at) as padding for the table top, as I had it flipped over on my portable bench for some work to be done on the backside. I've now flipped it over to prepare the top for finishing with multiple cycles of wetting to raise grain and sanding to smooth (120 grit) and the rags have left some distinct patches of something that is apparently oily. My concern is that these patches with be telegraphed into the water based stain finish. What can I do to ensure that this will not happen? A wiping of mineral spirits, or will my cycles of wetting/sanding take care of it? Any help or suggestions will be more than appreciated as I have about 85 hours into the entire table (nights/weekends) and I simply could not bear the idea of starting over.

Regards to any/all replies,
Ryan
 
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#4 ·
BrownTown,

I was not clear to me from your post whether you have already wetted and sanded the surface and the spots remain or whether you were about to proceed but did not because your noticed the spots. If no surface work has been done to the top, then perhaps these are surface blemishes left by the rags. The rags have been washed and I assume the rags were dry, and, so it may be that the contaminant is on the surface and a little dry sanding will lift the spot. Otherwise…

I like the mineral spirits and acetone suggestions generally. Mineral spirits will dissolve oily substances like motor oil and grease from a golf cart that were not removed during laundering. Acetone can dissolve both water soluble and oil soluble substances. Then there is water which is sometimes called the universal solvent and can be good for dissolving soap residue.

My guess is that one of these three solvents may remove the contaminant. However, it seems to me you are now working in the dark; which solvent is best, what affect, if any, will the solvent have on the wood, what is the best method for effectively applying the solvent, how much solvent to apply and how many times to apply are all unknowns.

Given the time spent on the project, perhaps a little experimenting would be helpful. Placing four weighted scrap pieces oak on the rags used as padding will hopefully cause the contaminant to be transferred to the scrap. If it does transfer, raise the grain as you plan and apply a coat of finish to the scrap. If the spot disappears under the finish, then I would think the problem is solved. If not, using each of the three solvents on the remaining test pieces could reveal the amount of solvent required, whether it needs to soak into the wood, and how many times the process must be repeated to remove the spots. Since the table is oak, the contaminant may have penetrated to some depth into the wood. If this is the case, then several applications of solvent will probably be required to remove the contaminant because each application of solvent may only remove some fraction of the contaminant.
 
#5 ·
Gentlemen,

Thank you for the replies. I was unfamiliar with acetone and its uses but I did do a little research and it will definitely be putting in the back pocket for future consideration. I also performed a few tests to replicate the situation as per the recommendation by JBrow. The mineral spirits worked to remove the patches but I did not like the color tone produced after staining. I let the mineral spirits dry for about 2 hours but maybe longer would have been better. Nonetheless, the test where I continued through the wetting/sanding process worked the best. I then took that to the actual workpiece, and I see no indication of the patches. Hopefully it's not just smoke and mirrors. Unless there is anything else I might be missing, I'll leave y'all alone and thank you for the input.

Thanks again,
Ryan
 
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