Expert: Eileen Cronk - 8/6/2009

Question
Hi Eileen,

I've just finished building some cabinets (solid maple, birch veneer ply) which I conditioned, stained with Varathane-brand wood stain, left for many days to cure, and then finished with three coats of Varathane (water-based).

The person I made them for has just called to say that small white spots are appearing on the surface and seem to be spreading!

(The spots disappear briefly when wiped with a damp cloth, but rapidly reappear). I don't yet know whether the spots are only on the top horizontal surface or on vertical surfaces as well.

Help! Do you have any idea what might be causing this, and what I can do to fix it?

Thank you!
Malcolm

Answer
Hi Malcolm
Nice to hear from you but wish it was better circumstances.
First off I see nothing amiss with your methods.
Two things come to mind. Are the spots only on the solid maple parts or are they on the birch veneer ply too? If only on the maple, its a moisture problem with the wood.
If the spots are on both, the problem is something happening with the finish and the conditioner could be the culprit.
What I am going to suggest as a cure may not sound Kosher but its worth a try. But you must do a test in a very small area.
Wrap a rag around the end of your finger and dip it in tung oil.
Gently rub this over a couple of the white spots. They will disappear (like they did with a damp cloth), but I'll bet they don't come back.
But wait a day to see. Tung oil is oil based of course and your finish is water based but don't be afraid to try this.
If this cures the problem, proceed to rub out all the spots with an overall very light application of the oil.
And Malcolm will you get back to me on this as I am very interested in this.
Regards
Eileen

Hi again Malcolm
Did you by any chance use a roller to apply the poly?
I was working at a job  where the owners had applied 2 coats poly to the wood floors.
The floors were covered with exactly what you describe..white spots that disappear when wiped but come back again.
The problem was with the roller creating bubbles. The owner did say that he noticed a lot of foaming of the finish as he worked the roller back and forth.
He applied a final coat of poly and the marks disappeared..but he used a brush instead of the roller.
So proceed with a light oil wipe test.
And let me know.
Eileen