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  #1  
Old 02-15-2019, 12:12 PM
hartguitars hartguitars is offline
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Default Lacquer over CA glue issue

I'm finding using medium CA glue to fill little gaps in bindings and the plates works well but then when I spray NC Laquer the lacquer beads away from the CA glue spot. Like oil to water. Does anyone have experience with this? I was wondering if de-waxed shellac on top of the filled spot to seal might help the NC bond better. What's the trick? This guitar was at buffing stage, and the buffing revealed a couple gaps. So I want to just fill with CA and then spray one final coat of NC.

Thanks for your thoughts
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Old 02-15-2019, 12:22 PM
Rodger Knox Rodger Knox is offline
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I don't use lacquer, but those that do usually do drop fills with thickened lacquer. CA is good with poly finishes, not so much with nitro lacquer.

I'm not sure where you should go from here, I suspect that the shellac would stick, but might be visible. Wait for someone that does use lacquer before proceeding.
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Old 02-15-2019, 01:08 PM
hartguitars hartguitars is offline
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Thickened lacquer makes sense. I've been drop filling with normal lacquer and its slow going. Shrinks, do it again... How does one thicken lacquer?
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Old 02-15-2019, 01:38 PM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by hartguitars View Post
How does one thicken lacquer?
Leave it out to evaporate some of the solvents.


It might be something in the accelerator, if you are using one, that is "oily". Have you tried a light sanding prior to applying lacquer? a coat of shellac might help. Try it, let us know. (I haven't used NC lacquer is a decade or two.)

If the neighbouring woods are dark, using the same material as the pore filler might work. Epoxy might also work: some use it as a pore filler. I've been using a water-based pore filler that dries entirely clear: dries in 1/2 hour, ready to coat.
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Old 02-15-2019, 03:11 PM
hartguitars hartguitars is offline
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Leaving it out did occur to me. I don't use an accelerant for that reason. I wouldn't want to add another substance. Since I'm working between the purfling and the spruce, i didn't want to use pore filler. (i don't have the clear which I should get) Is that the Aqua Coat you're using? I will keep you posted. For now I just did a drop fill along the CA filled spot. It's probably just patience I need. Eventually it will bond I'm sure. But I will try the shellac on a test piece of spruce to see if that allows the lacquer to bond. What finish are you now using?
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Old 02-15-2019, 03:24 PM
redir redir is offline
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I've used Nitro over CA and have never seen that behavior. Odd. What kind of nitro are you using?
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Old 02-15-2019, 05:27 PM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by hartguitars View Post
Is that the Aqua Coat you're using?... What finish are you now using?
In the last 40 years, I've tried a lot of things but not UV-cured finishes, catalytic lacquer or Taylor-style urethane. The current instrument is being finished with Royal-Lac. The one before that was Target EM6000. The tops of my classical guitars are usually finished with French polish.

The pore filler I used with the Target was "Brite Tone" made by the folks who make CrystaLac. It works okay, but takes numerous applications. It scrapes well but hopelessly clogs sandpaper nearly instantly. I very much liked that it dries FAST and is entirely clear, imparting no color to the wood. It doesn't smell great, but neither did the Target EM6000. Epoxy may be the next pore filler I'll try.
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Old 02-15-2019, 05:51 PM
hartguitars hartguitars is offline
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Quote:
Originally Posted by redir View Post
I've used Nitro over CA and have never seen that behavior. Odd. What kind of nitro are you using?
Seagraves NC Lacquer
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Old 02-15-2019, 09:44 PM
Glen H Glen H is offline
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I think you may have wax from the buffing in it, assuming you used a buffing compound.
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Old 02-16-2019, 06:50 AM
B. Howard B. Howard is offline
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What brand CA? I have seen issues similar with the gluboost stuff.
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Old 02-16-2019, 08:23 AM
hartguitars hartguitars is offline
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Quote:
Originally Posted by Glen H View Post
I think you may have wax from the buffing in it, assuming you used a buffing compound.
The fact that the lacquer lays down nicely everywhere else around the spot makes me think not, but thats a good point. I wasn't aware there is wax in the compound.
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Old 02-16-2019, 08:30 AM
hartguitars hartguitars is offline
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Quote:
Originally Posted by B. Howard View Post
What brand CA? I have seen issues similar with the gluboost stuff.
CA was Stewmac I think. medium
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  #13  
Old 04-16-2019, 02:53 PM
Terry Fritz Terry Fritz is offline
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Default Identical Problems with NL over CA

I have had the exact same problem using my lacquer over GluBoost products. I am using Mohawk Stringed Instrument Lacquer (thinned up to 10% with Mohawk Lacquer Reducer) and GluBoost Fill & Finish as well as GluBoost accelerator. There is clearly some kind of chemical reaction between these two products. It perpetuates in successive coats of lacquer. I have tried "sealing" the GluBoost with fresh shellac, tried sanding, tried wiping with naphtha. Nothing works.

For now, I have given up trying to use this brand of CA and accelerator under my lacquer finishes. A long time ago, I contacted the Technical Department at GluBoost and they said it was because I was using thinner to reduce my lacquer when the can says the lacquer is ready to spray.

I love GluBoost for other applications, but until someone can help me figure this out, I have ceased using it underneath of any NL overspray.
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