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Polymerized tung oil - curing to a clouded finish. Help!

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Forum topic by daveingva posted 05-26-2011 03:24 PM 5714 views 0 times favorited 8 replies Add to Favorites Watch
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daveingva

10 posts in 2019 days


05-26-2011 03:24 PM

Topic tags/keywords: question

Hello there,

I have a query about Lee Valley Tools polymerized tung oil. I’ve used it as my preferred finish – usually as a medium luster (1 part Sealer to 2 parts High Luster) – for many years.

This January I was unusually for me using the tung oil straight as a High Luster finish on a pear wood coffee table I was making for a friend. I was on my 4th and final coat, after having given 24 hours between coats. When I came out to my garage to check on my final coat I was shocked to see the finish had dried in a “clouded” fashion, with streaks of very matte type finish interspersed with the rest which was a brilliant gloss. I put that down to a rapid temperature drop and my workshop garage being unheated. It meant stripping the table and redoing the finish. One thing I did notice was the high luster tung oil I was using was the dregs of a can that had been opened for some time (perhaps even as long as 2 years) and which had congealed a skin across the top which I had poked through and worked with the uncured oil underneath.

Anyway, I had thought the January episode was a one off bit of bad luck related mostly to cold weather that dropped my workshop temp from 12C to around 4C and perhaps was also somehow related to using “old” tung oil which had skinned over.

Fast forward to today, where I have been applying some touch up maintenance coats of medium luster polymerized tung oil to a coffee table I’ve built and which sits in our living room. The tung has been drawn from a jar of a medium luster mix which I made back in January or so. I cannot remember if I was mixing sealer and high luster from cans that had been open a long time but as I live in Switzerland I have tended to buy things like tung on one off shipments and I cannot remember buying tung from LVT in the last 4 years. So probably whatever I am mixing up has been in the can for a good few years, although at least initially the stuff has never been exposed to air. So anyway, the medium luster mix would have been made in January but then had been sitting in a glass jar at a half full level and I started using it for my living room coffee table about 4 days ago. Once more I have been applying the tung with a cheesecloth and 24 hours between coats. The first 3 coats went on well, and last night I put on the 4th coat. I was surprised and very depressed this morning to find the 4th coat had again cured in a cloudy, matte fashion over approximately half the table surface.

This time the table was in our heated home, so a temperature drop is not the culprit. I have noted that in the jar I have been using there has been some congealing of some of the tung oil around the edges so that seems to be the only common factor between the two episodes. Is it possible that my entire stock of tung oil is simply out of date? Has anyone else seen this kind of thing? Does anyone have an explanation for what has happened? And is there any way I can salvage my table without stripping it all off and refinishing?

The followin photos show the sad story.

Thanks for your comments and advice.

Dave M


8 replies so far

View Steven H's profile

Steven H

1117 posts in 2521 days


#1 posted 05-26-2011 04:59 PM

BEfore applying any finish, what grit of sandpaper did you sand up to?

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daveingva

10 posts in 2019 days


#2 posted 05-26-2011 05:12 PM

Hi Steven,

I handplaned this table slab from a length of sipo. Sanding after my finish planing would have been my standard – up to 240, then raise grain, then cut back gently with 320 grit.

Between coats of tung I typically pass very lightly with 600 grit. In this case I actually used 2000 grit as this was some maintenance touch up tung oil I was applying as the finish has been “finished” for about 2 years and just needed a bit of freshening up. I can assure you that table top is perfectly flat and mirror smooth….

Dave

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Bertha

13003 posts in 2155 days


#3 posted 05-26-2011 05:15 PM

I’m wondering if a coat of wax might brighten it, now that it already there? I honestly can’t help you but I’m confident someone here will. I love Tung Oil but I’ve never used LV’s. What a reward for all that handplaning, huh? I hope you get it resolved.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Loren's profile

Loren

8301 posts in 3109 days


#4 posted 05-26-2011 05:17 PM

May be water vapor trapped under the varnish. Give it time –
the vapor will off-gas (if that’s what the problem is) and the
clouds will disappear.

It won’t be hard to scrape off the top coat with razor blades
anyway, so don’t panic. I’ve seen and dealt with far worse
finishing problems.

View Jack_T's profile

Jack_T

623 posts in 2493 days


#5 posted 05-26-2011 09:27 PM

I suggest contacting LV and asking them about the problem and possible solution.

-- Jack T, John 3:16 "For God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life."

View Steven H's profile

Steven H

1117 posts in 2521 days


#6 posted 05-27-2011 04:09 AM

Something tells me that you hand planned up to a point where the oil sit on top of the surface not into the wood. I could be wrong. I suggest you ask the folks at sawmillcreek.org

http://www.sawmillcreek.org/forumdisplay.php?23-Project-Finishing

View Billy_M's profile

Billy_M

1 post in 2016 days


#7 posted 05-29-2011 04:37 PM

I looks like what happens when I don’t sand or scuff the existing finish enough to give it some tooth. The new coat doesn’t stick so it just shrinks onto itself. Adding mineral spirits to thin older product seems to help as well. Just my 2c.

-Billy

View daveingva's profile

daveingva

10 posts in 2019 days


#8 posted 05-30-2011 05:32 PM

LVT customer service consulted 6 books and surmised that the final coats may have been a bit too heavy and not sufficiently cured. Another possibility is settled out flatting agents from the sealer component and it is true I do not remember shaking well etc.

They recommended trying a partial strip using turpentine which I did. After sanding I am now back to the original surface and have applied two (very thin) coats of a (newly mixed and well shaken) batch of medium luster. So far looks perfect. Will get a third coat on tomorrow and topcoat with pastewax.

Tx for all the inputs people, hope this info helps someone down the road.

David

PS: By the way, Lee Valley Tools continues to amaze me with their customer service. I cannot think of any other entity in the woodworking business that is so customer oriented, has such a deep range of woodworking products, and is a tool design innovator. If anyone here has never dealt with them you are missing something very rare these days. No connnection whatsoever to LVT….just a long time and completely satisfied customer.

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