Poly finish problems..


40belowwoodworking

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post-16421-0-02742000-1423278540_thumb.jFinishing a bookcase.  Applied Minwax stain, after sanding, 3 coats and wiped off thoroughly and allowed to dry completely. After the 2nd coat of Minwax Poly Satin finish these small white stains appeared. 1st coat of poly was dry (24H) and clean, no stains.. I lightly sanded the areas with 600 grit and fine steel wool, wiped areas down and applied the 3rd coat of poly. Within 30 min's the stain came right through. Original wood surface was clean, oil free, glue free.. Stain's did not appear until after the 1st coat of poly. So....What is it, how can I prevent it in the future and...how can I fix it??

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I remember something about the color "red mahogany" in minwax that needed special consideration. Other than that idk. 600 and steel wool is too fine. 240 or 320 then recoat. 3 coats outta level out darn near perfect. Especially with satin. 600 would polish satin to the next sheen level or at least close to it. It looks like inter coat adhesion problems. Good luck.

Steve

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Was it a new can of poly? Partially empty when you used it? Were you taking it right from the can or did you pour some into a secondary container? Satin poly has silica or other flattening agents to provide the satin sheen. What you're seeing could be where you picked up blobs or heavier parts of flattener. You need to keep it well stirred while using it so the silica stayed mixed in.

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Was it a new can of poly? Partially empty when you used it? Were you taking it right from the can or did you pour some into a secondary container? Satin poly has silica or other flattening agents to provide the satin sheen. What you're seeing could be where you picked up blobs or heavier parts of flattener. You need to keep it well stirred while using it so the silica stayed mixed in.

I think this is it. I was shocked at how long it took to stir the lumps out.

Steve

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To close this post...The advice I received I believe was correct. I don't think I stirred/mixed the satin poly correctly. To remove the stains, I used a cabinet scraper to carefully remove the poly on stained areas. I did notice an abrasivness as I scraped the poly which confirms the advice I received here. I used a scotch-brite pad and 600 grit to soften the surrounding area, touched up with a dab of stain and re-poly'd the spots. It really came out OK. So...stir better, and while staining and finishing is not my favorite part of a project...beer and Bob Seger make it bearable. Thanks for all the advice and suggestions. -50F here this AM

RW

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