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Hi all,
What polyurethane lacquer do you favor and whats your application process.
Best regards Geordie

As far as I know, there's no such thing as polyurethane lacquer. I use either automotive acrylic finish or nitrocellulose lacquer. With either one I follow a nitrocellulose finish schedule, more or less. This is pretty much it. http://www.stewmac.com/freeinfo/Finishing/Finishing_schedules/i-nitrocellulose.html
Except for the last part. 4 days is really optimistic, IMHO. I wait 4 to 6 weeks before final wet sand and buffing.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

"Polyurethane lacquer" is really two part automotive finish, which is more difficult to use but are almost bulletproof.

I won't use it on acoustic guitars... but many commercial manufacturer uses them because they are more production friendly.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Cool! Thanks, Tai fu. Learn something new every day.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

There's alot of overlap in terms used to describe finish types. I'm pretty sure there's hybrid finishes available that are nitrocellouse lacquer/polyurethane blends, but I haven't used any, and don't know if anyone uses these on musical instruments. Some builders use automotive 2K urethane, but it isn't designed for use on wood.

My favorite finish is oil based Varnish. I use Sherwin Williams fast dry oil varnish. I've made a DVD set outlining my varnishing process. It's available in the OLF classifieds http://www.luthiersforum.com/forum/viewtopic.php?f=10124&t=29995 or from the store on my website.

I also offer catalyzed urethane, (ML Campbell Euro series which is similar to automotive 2k urethane, but designed for use on wood) or Nitrocellouse Lacquer (Mohawk stringed instrument lacquer) as an option. I prefer oil varnish, and may stop offereing other options sometime.

I've done finishes with catalyzed polyester in the past, but no longer offer than option.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

I use an automotive clear coat finish and have no problems with it not being designed for wood. I used to use McFaddens catalyzed urethane which was similar but I thought it was not as acoustically transparent as the automotive finish is, had some adhesion problems and was a little harder to apply. As it is I can get a nice, thin, durable finish with minimal acoustic impact that doesn't take long to apply.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

I used a 2 part polyurethane finish system on five guitars. The guitar I have kept & play all the time has this finish on it. I really like using this stuff. Other than the careful mixing required, it is easy to apply, sands & buffs out super easy, to a brilliant high gloss.
It IS easy go get too much finish applied. Especially for someone used to using nitro.
The system I used is made by Becker Acroma & comes in three parts.
A sealer - Recommended for oily woods or wood with a very open pore structure.
A filler - Levels beautifully, but builds fast & is noticeably milky on pale woods like maple.
A top coat - Which BA calls lacquer, even though it is a two part Poly finish. I really like this stuff. I'm planning to do some adhesion testing in the spring, to see if I can use the Laq coat without the primer & base coats.
This finish will shrink down into pores, but not near as badly as nitro. One of the things I want to try, is to let the test pieces cure a month or so before levelling & buffing. If the tests come out well, I will probably go back to using this finish.

Thanks for your advice
Hmm this is intriguing.
Heres a quote from George Lowden on a Lowden players forum -
"We use a polyurethane material ( although from 1985 to 2003 we used an
acid catylised laquer ) The system of working to achieve our satin
finish involves sprayings several coats of lacquer and rubbing down
very thin in between coats. Then the final coat is rubbed with #1000
paper used wet in parallel lines and then steel wooled, also in
parallel lines. Other factory satin finishes are simply sprayed on and
left as is "off the gun" as we say".
I have a '86/'87 and the finnish is still "bullet proof" though it has gone cloudy / white on the lower
bout where by upper arm rests according to his info above it will be acid catylised laquer (what ever that is) is there any way of removing this "opaqueness" ?
I just like the finnish on Lowdens and wondered about using it myself.
best regards
Geordie

Geordie, "acid catalyzed lacquer" sounds to me like conversion varnish. I use varnish, but not "conversion" varnish, which isn't the same thing. Some of the cabinet builders here may be able to advise you how to remove the haze. I believe Mr Lowden is usually responsive to questions. He may have some advice to offer if you ask him. I've never spoken with, or e-mailed him though.

Daniel, if you like the Becker Acroma 2k urethane but don't like the shrinkage, pore filling with epoxy before applying the sealer may help. When I use 2k urethane I still wait 2 weeks before buffing. Becker Acroma is now owned by Sherwin Williams.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Dave,,, Have you ever used Acid Catalyzed laquer? If so, what's it like to drop fill and touch up...if you ever had too?

Ken,,, What brand of catalyzed urethane do you use? I have tried Dupont Nason spot panel brand that Todd suggested and liked it, durable, little shrinkage, relatively inexpensive and able to buff in a couple days. I did miss the amber tint and ease of touch up of nitro, so predominantly use nitro.

Thanks
Chuck

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Dave, which one?
I found the site recently (after reading this thread)
I take it you have tried one or more of them.
I am interested in a water based, any guidance would be appreciated - being in the UK I fwould have tried the EM6000 but can't find a supplier here, and importing more than doubles the cost.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Chuck - No I use their pre-catalysed lacquer - the high solids one that new coats burn in on and can be easily re-sprayed/repaired.

Colin - My guidance on water based lacquer is don't touch it with a bargepole. That's just my personal view of it and others who love it and use it may chime in for you.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Geordie: On furniture, hazy finish is often from moisture trapped underneath. Could be from perspiration where your arm touches the lower bout? I've read it can be removed by giving the area a wipe with a little denatured alcohol. Theory is as the alcohol evaporates it draws the moisture to the surface. I don't know how it will effect your guitar's finish tho.

At the last cabinet shop I worked at we used a conversion varnish called Krystal. It sprays easily and is super clear and durable. I met an amateur builder who used it on a few instruments and had good results. The biggest downside I imagine is that it can't be repaired easily like nitro.

Anyone else tried this stuff?

-Jake.

Many thanks all,
Dave, there's a supplier in Glasgow I'll give them a visit.
chinito, yeah I was thinking it probably is twenty odd years of sweat from my oxter (u might need to Google that)

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some tunes on acoustic and guitar synth.
http://www.youtube.com/user/TheGeordieAdams
http://www.myspace.com/geordieadams

I'm happy with this one...
mix 1:1 apply and tomorow you can buf it


best
fric

Chuck, I use Dupont Chroma Clear HC-7776S snap dry clear coat. The second part comes in various 10 degree temperature ranges. The disadvantages are shrinkage and repairability. It also lacks an amber tint, a little of which would be nice. But it's water clear and has none of that bluish tint of some finishes. It buffs nicely with Menzerna compounds. To combat shrinkage I make sure that my CA pore fill has hardened for a few days and I let the two base coats cure for a few days before spraying the top two coats. Then I can buff the next day. For repairs it's best to sand and spray a whole panel.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Ken, I knew there was a builder/finisher that I respect and admire using an automotive urethane. It was you, but I had forgotten who it was. Do you use any kind of isolate type sealer/ barrier coat or spray it directly on the wood? (or is the CA a barrier coat)

Reguarding amber tint, I know a couple finishers (using polyester) who use a coat of Waterlox over their pore filler, under their barrier coat to warm up the wood colors. It may work with your finish.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

You're right, Woody, for me the CA is the sealer. There is no sealer on the top though and the adhesion is excellent there. The first coat on the top can be a little rough but it sands out fine. Thanks for the tip on the Waterlox. Sometimes I use shellac before the CA and that warms things up a little.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

How do you use CA as a filler? the fumes must be overwhelming.

There has to be better way to seal wood pores than using CA... I think polyester is better for that.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

I use goggles and an organic vapor mask. I spread medium viscosity CA with a latex glove and do a panel at a time. Then I leave the shop or hang it outside. With the mask and goggles I can't sense the fumes. The medium viscosity CA fumes less than thin CA. They have a low fuming CA but it is quite expensive.

_________________
Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com