Might be dust or air bubbles. Either way, if they are small nobody but you will ever notice them. My rule of thumb is if it looks good from ten feet away it's okay. I had some white streaks where dust got under the epoxy on the hybrid deck. I painted over them with model railroad weathering paints that were similar color to the cedar. -Wes

Thanks Wes.  I think I will treat the spots as you suggest.

I've read and re-read "Twofootartist's Random Ramblings" on the construction of your Shearwater and Merganser Kayaks.   Your work is exceptional.  Thanks for the insight and the construction progress reports.  ~ Roger

you can try to use compressed air to blow it out. if this are air bubbles, that's the only way I found to remove the white dust. I've tried a lot of different things so far. And I fully agree with Wes: If they are small, nobody than you will recognize them :-))

Rudi (aka burningman)

I discovered the same thing (tiny white spots) today after sanding my WD tandem deck for the first time.  Wondering if anyone has come up with further thoughts or solutions since dunhr's post last month

Here's background:  Building in my heated garage which has been kept at pretty constant temp of 62-65 degrees.  Applied 5 thin weave filling coats to deck per CLC tips for builders (i.e., foam roller followed by tipping with foam brush).  Spots are fairly prominent on bow between coaming and hatch, nearly completely absent on rear deck--both of which were done at the same time on all five coats.  Spots are all in sapele, none in okoume.

Ideas re: cause or cure?

Dave

The white spots are air bubbles caused by outgassing during the epoxy curing stage. Then filled with epoxy dust during the sanding stage. Vacuuming with a shop vac will get some of them out. Compressed air for the others.

Thanks, jnjclark.  The spots were very tiny and patterned like a grid.  I assume they originated with air that came up through the weave.  I was concerned because they didn't disappear when rubbed with alcohol or even diminish noticeably with compressed air.  But you guys were correct--altho still visible, they are much less so when covered with a skim coat of epoxy.  All has ended well, and I'm now a full fledged member of the "ten foot club." 

Dave