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Pre-cat lacquer flaking

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Forum topic by michelswoodworks posted 12-16-2018 03:16 PM 577 views 0 times favorited 7 replies Add to Favorites Watch
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michelswoodworks

7 posts in 251 days


12-16-2018 03:16 PM

Topic tags/keywords: lacquer poly-urethane lacquer flaking

I built a red oak table top recently. I did some breadboard ends that I joined with dominos. I allowed for expansion and contraction in the joint. I sprayed it with some pre-cat lacquer. Well, first I applied GF oil based gel stain. I waited 72 hours and then sprayed 3 coats of sanding sealer, sanding with 320 in between. I then waited overnight and sprayed pre-cat lacquer, 3 coats without sanding. I laid it on pretty heavy. It was BEAUTIFUL! A few small imperfections, but it was an even satin sheen that was glassy smooth to the touch. I let it sit for a few days and then went to pick it up to deliver to my sister. To my dissapointment, there was some flaking, crackling, peeling, whatever you want to call it. It only happened where the breadboard ends met the table top. The only thing I can think of causing this is expansion and contraction. The top was sprayed at about 60 degrees or so, maybe less. I’m in Utah so it’s pretty dry. Anyways, it was left in a shop that isn’t climate controlled. There was some guys working there one day so they probably turned the heat up so it was exposed to some temperature changes. Also, I noticed that the flaking only happened where the breadboard end is tight. There are some areas of the joint that have a small void. I’m thinking the lacquer didn’t bridge over the joint, so when the top contracted, the lacquer didn’t break. But where the joint is tight and the lacquer has bonded over it, it broke. I’ve talked to a couple finish gurus and they all seem to agree that lacquer doesn’t have any elasticity. It’s very hard but brittle. They claim that a polyurethane has some more flex to it. At this point, I want to strip the entire top, restain it and spray some two part milesi polyurethane. It’s been recommended to me by two guys so far. A guy at woodcraft seems to think that GF arm-r-seal is the way to go. But I’m already so deep into this project I don’t care how long or how much it costs, I want the best. im also worried about stripping the finish but not getting all the way into the pores of the oak. If there are still traces of sanding sealer in there, will it somehow effect my future finish? The guy at woodcraft suggested I fill the grain and then stain it. At this point I want to strip it and spray the milesi but I want to confirm that my hypothesis is correct before I do anything. Will a polyurethane, which is supposedly flexible, be a better option? Thanks in advance. I’ll include some pictures


7 replies so far

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Phil Soper

25 posts in 255 days


#1 posted 12-16-2018 04:06 PM

You are correct. The flacking is caused by movement in that joint, something you will not stop. Any hard finish that bridges that joint will break when the wood moves. I would suggest cut the top joint with a v cutter in a router, refinish and then cut open the finish at the bottom of the v. That will allow for the movement.

Another option would be to sand enough to remove the lacquer that is bridging the joint or carefully cut the top of the joint and then respray with the special automotive clear-coat that is used on the flexible bumpers

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Rich

4701 posts in 1043 days


#2 posted 12-16-2018 04:32 PM

At what temperature was the table stored? Lacquer — especially catalyzed — is very brittle at low temperatures. It’s particularly an issue within a couple of days of spraying.

Also, who catalyzed the lacquer? Over catalyzing can cause checking as well due to increased brittleness.

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

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michelswoodworks

7 posts in 251 days


#3 posted 12-16-2018 04:33 PM

Thanks for the reply. Do you think something like milesi 2k polyurethane would have enough flex to move wth the wood?

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michelswoodworks

7 posts in 251 days


#4 posted 12-16-2018 04:38 PM

It was pretty cold. I would say around 40-50 degrees. There were some guys working in the shop that turned the heat up when they were working so the top was exposed to some drastic temperature changes, especially because it was stored right under the heater. I bought pre-catalyzed lacquer from a local paint store. I think it was valspar. I thinned it with lacquer thinner about 25%. The reason I sprayed it so cold was because when I was spraying my sanding sealer, I was getting a lot of graininess. I read somewhere that it was caused by spraying when temperatures are too hot so I just turned the heater off and it solved the problem.

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000

2859 posts in 1353 days


#5 posted 12-16-2018 04:49 PM

It doesn’t look like the chips were caused from just wood movement.
To me, and I could be wrong, it looks as if someone pick up the table by the breadboard ends and they flexed, therefore pinching the lacquer and causing it to chip.

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michelswoodworks

7 posts in 251 days


#6 posted 12-16-2018 05:12 PM

I hadn’t thought of that. If that is the case, cutting a v groove and spreading the finish in the bottom of the groove should still work, right?

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Rich

4701 posts in 1043 days


#7 posted 12-16-2018 05:19 PM


It doesn t look like the chips were caused from just wood movement.
To me, and I could be wrong, it looks as if someone pick up the table by the breadboard ends and they flexed, therefore pinching the lacquer and causing it to chip.

- jbay

Sounds right. Unfortunately it looks like a difficult repair due to the sharp edges which will be hard to obscure.

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

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