Finishing issue - light specks in grain

[Whit Preston]

Hi – Some years ago I did a kitchen build using Birch ply for the cabinet and drawer faces. When I finished them with oil based poly, there were considerable light colored specks or ‘blotches’ in some of the grain, which I could only imagine was fine sawdust that had gotten lodged or trapped in the grain. It was bit perplexing, as I had sanded with an orbital with very good dust collection, followed by vacuuming the faces well, and then used a tack cloth as a final pass. The effect was not consistent across the entire face, and am wondering if it might be a result of the grade of birch ply. The ply, while from a professional lumber dealer, not a box store, is still of a cheaper grade. Or perhaps a result of a poor finish technique on my part, perhaps sanding too too fine a grit (I seem to recall 220 as the final). I’m about to do another kitchen in a similar material, and want to prevent this problem. Thanks in advance for any thoughts.

Summary: Birch plywood, sanded to 220, vacuumed and tack cloth, then Oil-Based.polyurethane, no stain.


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[Richard Coers]

Specks or blotches are two distinct issues in my book, not similar at all. You can get specs from poorly mixed satin or low sheen poly from the flattening agent settling out in the can. Blotches would be a reverse in the grain, and if not sanded well enough with courser grit paper can look like minor tarot. I feel the only way to clarify is to see some pictures. Otherwise, you will get wild speculation and guessing the issues.

[Robert Hayward]

Strangely, I have reposted the images, and while I see them prior to saving the edit, they just show up as names after saving. Ah well...

That is because you are not a contributor. Only a contributor can see images in posts. $6.00 to become a contributor, well worth the small amount of money.

[Andrew Hughes]

My guess is contamination from the tack cloth. Too me it looks like the white wash stain didn’t bind to the plywood in those area.
This is my guess from a thousand miles away.
Good Luck

[Whit Preston]

Thanks; I just updated that.

[Rich Engelhardt]

It looks to me like you sanded through the veneer.

[Stan Calow]

Instead of a tack cloth, I use a towel, fairly wet with alcohol or some other solvent to wipe off the dust. It does sometimes tend to settle in those places that are below the surface.