Haze on Wood Finish

[kwik_wurk]

On my latest woodwork project (which happens to be not a Whaler), my finish coat ended up with a satin finish instead the expected semi-gloss finish and looks hazed. I am perplexed as to what would have caused this, as all the prior coats went down fine, and I really didn't change much, other than the wood was slightly warmer. I say this because the prior coat was actually much glossier, and was actually what I wanted and expected.

The finish is a urethane, and this was the fourth coat that was applied to the lightly sanded (220 grit) third coat at about 65 to 70°F and about 40 to 50-percent humidity. This was done in a garage inside screened section with plastic for dust control. All for most of the day the wood was indoors at 70 to 75°F temperature, and inside the garage I had two temperature sensors, with the temp starting at 70 and in the morning was 64°F.

The can of urethane was pulled from what I call my "clean finish" jar, that is only used on the final coats so there are not debris from prior coats (such as bits of dust, sanded materials). And another project looked fine.

Any ideas on the cause of the haze? From what I can tell it is only the surface of the finish that is affected, and not the entire coat being cloudy. I am a little perplexed, as I have done a many, many projects and never seen this happen.

Luckily it is only a small table top, so scuffing and re-finishing is not too much effort. However I do need to wait another day or two to get the paint fully cured, as the pieces have a holes and notches with pooled urethane that needs to completely dry. Or, I was thinking of polishing, but re-coating would be much easier.

Thanks.

[Binkster]

If you have to wait a couple of more days for the varnish in the crevices to dry, you must have applied the last coat too heavily. That might be the reason for the hazy finish.

rich

[Dutchman]

kwik_wurk
Thanks for giving the temperatures and humidity as that from my experience is what caused your hazing.
I had this happen to me once while varnishing the transom of an old Chris-Craft. It had never happened to me before and I did as I always had done.
After research I discovered that due to the heavier final coat together with the temperature difference overnight (although slightly) and the change in dew point the varnish absorbed some moisture. Waiting for a full cure will not gloss it, it had to be re-sanded and re-coated with great final result.
Sorry,

[kwik_wurk]

The final coat was thick but not excessive. The only thing I can come up with is the slight temp swing and having the wood warmer than the garage itself. I use a remote temp sensor when doing wood/fiberglass projects just to keep an eye on the temp.

The wood is actually teredo wood (aka shipworm) so it has lots of holes, and places for finish to pool up. Hence an extra few days are needed for the pockets to cure. (And I deliberately did not fill the holes.) -- I'll try and get a picture (without the haze).

[Dutchman]

One other thing you can try next time is using an accelerator/hardener.
The holes(pin) might also had more moisture in them that the surface had.
Good luck.