Lacquer cure time

[aniki]

I’ve just started a new project based on a Fender Dirnt neck and guitarbuild 54 body.

I started with Black water based wood dye to get the (almost white) wood really dark.

Then moved on to a water based wood stain for the final darkening.

Once that was dry I started applying thin coats of water based clear lacquer until I got it just where I wanted it.

The lacquer dries to touch almost instantly but it’s still very delicate.

After 24 hours I still easily scratched it with a finger nail. I’ve read of similar issues on furniture finishing forums and the consensus seems to be that lacquers actually take several weeks to ‘cure’ and become properly hard and resilient.

Does this equate with the experience of builders on here? Obviously I’m desperate to finish the build but I don’t want to wait for weeks only to find the lacquer is still soft and there’s something obvious I’m missing…

Many thanks

[Chienmortbb]

When I researched this some years ago, even many of the solvent based finishes took weeks to fully cure. Of course there will have been advances over the years. It might help if you mentioned the type and brands you have used.

[aniki]

Thanks. The lacquer I used is manufactured by Hemway. Opinions are quite divided on it based on Amazon reviews.

I contacted them and they were quick to respond and advised that all polyurethane lacquers will take at least 2 to 3 weeks to fully harden. Longer for oil based.

I guess I’ll just be patient. If it works I’ll put up a proper build thread. I’m very happy with the final look so hopefully it’ll work out well!

[rwillett]

11 minutes ago, aniki said:

Thanks. The lacquer I used is manufactured by Hemway. Opinions are quite divided on it based on Amazon reviews.

I contacted them and they were quick to respond and advised that all polyurethane lacquers will take at least 2 to 3 weeks to fully harden. Longer for oil based.

I guess I’ll just be patient. If it works I’ll put up a proper build thread. I’m very happy with the final look so hopefully it’ll work out well!

 

Good information, thanks for checking. Please do a proper build thread.

Rpb

[Andyjr1515]

Yes - other than some two-pack products (need equipment and pro-level skill) or industrial processes (need an industrial estate and a small fortune) then most gloss finishing products - whether they are water-based, oil-based, wax-based or spirit-based - that are readily available need a good few weeks to fully harden.  Some take months.

 

Most of the products I use (haven't yet found a water-based that has been successful - but that's probably me and not the products), generally old-fashioned high-volatiles polyurethane varnish or the much more environmentally-friendly wax-based Osmo ranges, are handle-able within 24 hours and some can be polished up within a week, but the fingernail test is a tough one.  Nitro-spray needs special health and safety precautions but is polishable quicker - not sure, though, how they fare with the fingernail test (and some - look up Gibson Sticky Necks on Google - never fully cure).  Some of the finishes I use will never pass the fingernail test.

Edited August 10, 2023 by Andyjr1515

[Waddo Soqable]

I'm rubbish at spraying and refinishing so consequently hate it, it always come out shlt unfortunately, and I've ended up scraping it all off again. I think the only usable results have been with basic Halfords car paint, even then its more the "rat look" that prevails. 

I assume the generally available nitro spray cans from the "guitar tech" type places are viable, with suitable drying time, possibly lack of patience is my main problem 😁

[Richard R]

Dumb question time:

What's the difference between lacquer and varnish? I have varnished tables, floors, etc, in the past and not had to wait weeks for things to harden. 

Or maybe I should have?

Edited August 10, 2023 by Richard R
Typo

[Andyjr1515]

2 hours ago, Richard R said:

I have varnished tables, floors, etc, in the past and not had to wait weeks for things to harden.

Yes - but you probably won't have done the fingernail test.  It is a very severe test, especially with some of the softer woods that are used in guitar/bass building as the finish has to be stronger than the underlying wood, otherwise it flexes, the wood underneath starts to deform and then the whisper-thin finish gives way.

[Andyjr1515]

2 hours ago, Richard R said:

What's the difference between lacquer and varnish?

I'm sure once upon a time there was a difference (I think I remember that all lacquers were types of varnish but not all varnishes were lacquer), but in common parlance the terms are pretty interchangeable 

 

[Andyjr1515]

With all the AI shenanigan's going on, there is no guarantee that this is correct, but according to that great cloud in the sky "The difference between lacquer and varnish is the type of finish used. Lacquers are thin, fast-drying finishes, while varnishes are thick, slower drying finishes."   But maybe the actual facts have been lost in English/Russian/Chinese/Many other World Languages translation...

Edited August 10, 2023 by Andyjr1515

[JPJ]

My general rule of thumb with nitro is 4 to 6 weeks, longer obviously better. Funnily enough, I’ve had a black nitro pass the fingernail test at three weeks, whereas a surf green took 8 weeks and was still softer than I would have liked when flatting and buffing. Mind once the nitro has stopped flashing off (i.e. doesn’t stink) I hang bodies and necks in the airing cupboard (much to Mrs JPJ’s disgust) as the heat helps with the curing.