Spraying Urethane vs. Polyurethane

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Danley
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Spraying Urethane vs. Polyurethane

Post by Danley » Mon Jul 22, 2019 9:20 pm

So I’m about to get a Squier neck someone sanded the back finish from - hate it when people do that :fp: Anyway, part of me wants to just shoot nitro on it and wet-sand down for a satin finish, but realistically this is my knockaround guitar and I’d rather have it be durable. Speaking of which, I really like the urethane finishes on my recent American Fenders- thin, durable, feel less plasticky than poly, doesn’t crack like an eggshell etc.

This neck has a polyurethane finish - or there are remnants of this finish still attached elsewhere on the neck anyway. Since urethane is softer than poly, is it reasonable to spray urethane over existing poly, or is there some possible reaction between the two? Further - has anyone ever used ‘spar urethane’ on a guitar? Apparently this has a yellow tint (good) and is meant primarily for outdoor use; it seems readily available.

For that matter has anyone ever bothered finishing a neck with spraycan poly or urethane of any sort? Experience?
King Buzzo: I love when people come up to me and say “Your guitar sound was better on Stoner Witch, when you used a Les Paul. “...I used a Fender Mustang reissue on that, dumbass!

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ludobag1
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Re: Spraying Urethane vs. Polyurethane

Post by ludobag1 » Tue Jul 23, 2019 2:58 am

i don't know the compatibility of the 2 but my 2 cents is otate all the older finish before redoing it ,if not will have change of colours or miss of adhesion from the new
if you have trouble to sand it ,scraps it with a razor blade and after sand the all with 320 grit

i have use a can of urthane of poly urethane one time and it doesn't dry ,2 years after it stay soft and take the marks :fp: too bad cause this varnish spray well ,and was easy to polish and buff ,then i redo this neck in true oil ,and i like the touch of trus oil on neck ,more fragile than 2k varnish but if you make a bump it doesn't crakle

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Ronkirn
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Re: Spraying Urethane vs. Polyurethane

Post by Ronkirn » Tue Jul 23, 2019 8:36 am

urethane and polyurethanes are the same thing... within the bounds of, there are many different formulations of the coating... some use no additive for the catalysts. instead they use the moisture in the air to catalyze the finish,.. these are what ya find in rattle cans... run away from 'em.

the two part coatings are what's used professionally, they require the "paint" then you must add a certain amount of another chemical which is what causes the poly to harden..

However there are "polys" that use light, UV light, Heat, High frequency sound and other weirdness to act as the catalysts...

so... now you're even more confused, hum??

r
“It’s easier to fool people than to convince them that they have been fooled.” Mark Twain

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Danley
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Re: Spraying Urethane vs. Polyurethane

Post by Danley » Tue Jul 23, 2019 9:52 am

More encouraged to just use nitro :D I’m figuring since I don’t want a gloss finish anyway, I can perhaps lightly dust coats on and give ample time for each to dry (as they are catalyzed by the air/sun/whatev.) Unless it’s not too difficult to run to a separate catalyst?

As for oil finishes - my understanding is the durability of these (at low thickness) is less than nitro?
King Buzzo: I love when people come up to me and say “Your guitar sound was better on Stoner Witch, when you used a Les Paul. “...I used a Fender Mustang reissue on that, dumbass!

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Re: Spraying Urethane vs. Polyurethane

Post by ludobag1 » Tue Jul 23, 2019 11:59 am

my true oil neck have 3 years now and it is one of the guitar i use the most ,at home i play really often on it and at rehearsale ,it is like at the beguin
it is not bullet proof but is it really easy to do ,a varnish is more hard

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