Finish Problem

Cody Colston

Member
Messages
336
Location
Tyler, Texas
I made an Eastern Red Cedar blanket chest on consignment. The lumber was kiln dried from a local sawmill where I have bought before.

After construction, I applied a coat of BLO, waited 15 minutes and wiped off the excess. The next day I did the same thing. The chest then sat in the shop with the BLO curing for 18 days.

This Saturday I applied two coats of Zinnser Shellac seal coat about four hours apart and sanded in between coats with a gray Scotchbrite pad. This afternoon, I applied three coats of USL with about 2 hours between coats. I did not sand between the USL coats.

After the last coat of USL had dried I noticed that the finish had a sort of crackled look in places. It's smooth to the touch but some light sanding with 320 grit made the crackle look really show.

I was thinking the Zinnser seal coat was dewaxed but the crackle look makes me think it wasn't. Does anybody have any ideas why it turned out like that? I'm probably going to have to sand it off and start over now.
 
I hope someone more knowledgeable than me chimes in, but I recall reading somewhere about issues finishing some types of cedar due to the natural oils in the wood. I wonder if that might be what's causing the problem? :dunno:
 
Cody...

I don't much about BLO, but fwiw I've been studying polymerized tung oil which has become my preferred finish. Sutherland Welles website instructs that even if wiping it on it's important to let the first coat thoroughly cure before wiping on the second coat. Otherwise you can trap moisture between the first two coats, which causes "flashing"...don't know how flashing relates to speckling. In the case of pto the day in between coats would have been okay...maybe blo takes longer to fully cure (in Sutherland Welles vernacular "fully cure" means not that the solvents have evaporated, which happens fairly quickly, but that the oil itself has cured).

I've also read the thing about cedar that Vaughn mentions, but have no first hand experience.

Sorry about the lean advice.

Good luck with it. Would like to know how you eventually solve it.

Cheers.
 
Cody,
It has been commonly posted on other forums that the Zinsser SealCoat has coused problems with the Target USL when the SealCoat has been applied in too thick a film. Below is a post from the Target Forum, by Jeff Weiss, of Target Coatings. There have been many posts regarding your problem and it appears that SealCoat seems to work fine when applied sparingly under most WB finishes.
Conard


Jeff Weiss
Site Admin


Joined: 23 Jul 2005
Posts: 1220
Location: Little Falls, NJ USA
Posted: Wed Dec 05, 2007 8:07 pm Post subject:

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Dave,
You should be ok with the SealCoat. It is wax-free.
However, there have been reports of SealCoat crazing/crackling underneath mild pH WB finishes such as USL and othe brands of WB's. Make a test panel to ensure compatibility.

JW
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