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Lacquer still sticky/gummy 4 months latter?


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Title says it all, and I would *really* appreciate any tips you all might have.  I finished a guitar in Mohawk Satin lacquer from rattle cans about 4 months ago, thinking it would work well because I've used Mohawk in the past for spot repairs and it worked wonders.  I've previously used StewMac and Re-Ranch rattle cans with great results, and like I said I've used Mohawk for smaller stuff so I started shooting without a care in the world...

However, after following all the usual lacquer spraying rituals (lots of can shaking, 12ish light/medium coats spread out over the course of a week or so with some mild level sanding in between, ventilated indoor spray booth at moderate temps and approx 40% humidity, let it dry for about 2 weeks before assembling) this finish is still the stickiest I've ever felt and we're about 4 months out from when it was done.  I sanded the neck to 1000 grit to try to solve the issue months after it was finished, and when I did it felt just like lacquer does when you sand it too soon after shooting (the finish's sanding residue starts rolling up in those little clumps underneath your sandpaper and gums up the grit in the sandpaper very quickly). 

I have no idea how it happened but it's as if there was a major issue with the solvent mixture and a bunch of it is trapped in there still; the whole finish all over the guitar just feels wet, like it never really dried.  Maybe the cans I bought were ancient and something went wrong with the contents?  Even the 1000 grit sanding didn't do much for the situation, and the neck was feeling gummy and gross again not long after.  I've heard that you can potentially save lacquer finishes like this by spraying the entire guitar with blush-out to re-flow the finish and hope whatever solvents may be lingering therein will get another chance to dry out.  Is that true?  I've only used blush remover for actual blush problems, not "fixing" a wet lacquer finish that never dried.  

I'm getting close to tearing the entire finish off and refinishing with something else, so if someone's got any easier ideas I'm all ears!  Even if saving it with blush remover is a long shot I can't really see a downside to trying it I suppose, cause if that doesn't work I'm just going to have to refinish it from bare wood anyways.  The sticky body and neck are absolute deal breakers for playing live - it's super distracting and uncomfortable.  

Any and all advice welcome!

 

 

 

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No advice from here but I think I know what you're talking about. The tabletop my brother-in-law lacquered with a brush remained sticky for years and got worse every summer - either because of the heat or because our arms weren't covered.

Rather than having solvent trapped within the layers I suppose that the solvents may have evaporated from the cans because of aging or poor storaging, causing plain lacquer being sprayed. Logically thinking the reason for using solvents is to make the sticky lacquer dry faster as the layers will be thinner, thus getting thoroughly dry before the next layer. With plain lacquer several layers in a week might just be too fast a pace! All that assuming that there wasn't enough solvent left in the cans to start with.

If that's the case I'm afraid there's no valid method of reapplying solvent to the semi-dry finish so tearing the finish off and refinishing may be the only route.

In some tutorial I've learned that despite what the manufacturers say, there's no such thing as too much solvent! The more evaporating solvent you use the thinner layers you get and the faster they dry.

Just for clarification I'm not talking about water which is a solvent widely used in water based finishes!

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You said you left it 2 weeks then assembled, what about levelling and buffing? If you didn't do any sanding then I reckon theres a chance that you've got a lot of finish on there with some trapped solvents, so it stands to reason that it didn't cure for long enough. Even after levelling I think you need to leave it a while before buffing so the newly exposed lacquer has time to harden. I see all over the internet that lacquer must be left for a month before buffing, I don't leave it that long but I'm so crap at spraying that I end up sanding at least half the finish off so there is a lot less finish on there to cure, the precat stuff definitely doesn't need as long to cure either - When I spoke to Morrells (the lacquer I use) they reckoned 3 or 4 days should be enough cure time but I still leave it a couple of weeks between final wet sanding at buffing.

I doubt any of the above actually helps your current situation but I think ultimately you just didn't leave it long enough.

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8 hours ago, Bizman62 said:

Rather than having solvent trapped within the layers I suppose that the solvents may have evaporated from the cans because of aging or poor storaging, causing plain lacquer being sprayed. Logically thinking the reason for using solvents is to make the sticky lacquer dry faster as the layers will be thinner, thus getting thoroughly dry before the next layer. With plain lacquer several layers in a week might just be too fast a pace! All that assuming that there wasn't enough solvent left in the cans to start with.

If that's the case I'm afraid there's no valid method of reapplying solvent to the semi-dry finish so tearing the finish off and refinishing may be the only route.

 

This sounds like it might be what happened - whether there's solvents trapped under the top layers of lacquer or the layers below the top one it never had enough solvent to begin with and were really shot closer to "straight up lacquer" level of mixture, I'm not sure.  All I know for sure it that the finish is still wet somehow.  One thing that I might try is sanding down the finish a bit with a rough grit paper like 220 or 320 to expose as much of it as possible without getting down all the way to the wood, and then trying the blush-out trick to reflow the freshly-exposed lacquer and giving it a few weeks to dry and see what happens.  If it still feels wet after a month or so after that I'll know it didn't work.  It's a satin finish that I initially thought I might have matte/flat, so I don't mind if it sinks down in the grain again and I get an open pore look as long as it hardens.  If that doesn't work I guess I'll just strip it.  

 

6 hours ago, ADFinlayson said:

You said you left it 2 weeks then assembled, what about levelling and buffing? If you didn't do any sanding then I reckon theres a chance that you've got a lot of finish on there with some trapped solvents, so it stands to reason that it didn't cure for long enough. Even after levelling I think you need to leave it a while before buffing so the newly exposed lacquer has time to harden. I see all over the internet that lacquer must be left for a month before buffing, I don't leave it that long but I'm so crap at spraying that I end up sanding at least half the finish off so there is a lot less finish on there to cure, the precat stuff definitely doesn't need as long to cure either - When I spoke to Morrells (the lacquer I use) they reckoned 3 or 4 days should be enough cure time but I still leave it a couple of weeks between final wet sanding at buffing.

I doubt any of the above actually helps your current situation but I think ultimately you just didn't leave it long enough.

It's a satin finish so there was no final sanding a buffing.  I sprayed 2 or 3 coats a day over the course of a week with a day in between, after which I would sand level and let dry for another day before adding more coats, and the final spray was a fairly light 2 coat process, so whether I assembled the guitar the very next day after that or months later wouldn't change anything about how long the finish had to dry out after that since there was no "final" sand and buff.  I think either I sprayed coats too quickly, too heavily, or there was a solvent mixing (or missing solvent) issue, or some combo of all of the above.  Obviously I have no way to confirm my theories, but like I said above I think I'll sand the finish down a good bit and try to re-flow it, if that doesn't work, it's orbital sanding time!

 

 

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My very first build I sprayed acrylic lacquer (automotive) from rattle cans and experienced the same thing. 6 months after spraying it you could lay it on a tee shirt for a couple days and when you picked it up there was an impression of the fabric in the clear. It did finally get hard after about a year.....

SR

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2 hours ago, ScottR said:

My very first build I sprayed acrylic lacquer (automotive) from rattle cans and experienced the same thing. 6 months after spraying it you could lay it on a tee shirt for a couple days and when you picked it up there was an impression of the fabric in the clear. It did finally get hard after about a year.....

SR

It's been so long since I used regular lacquer (usually using oil these days) that I just didn't anticipate this at all.  Oh well, we'll see how the coming months treat it, maybe it will dry up in the long run after all!

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3 hours ago, Lumberjack said:

maybe it will dry up in the long run after all!

Most stuff will do that, the problem is that it might take years or decades. Hopefully not, though!

 

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