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OK, so I'm finishing a tele from warmoth. Alder that I stained and I now have 11 coats of General Finishes High Performance Polyurethane on it. (supposed to be very hard for tabletops etc.) It looks great. But if I take my fingernail I can dent the finish. Why is it so soft? I have followed the instructions explicitly. Wipe with foam brush, let dry over 4 hours. Lightly scuff with 400 grit, wipe with tack cloth and reapply. Do I just need more coats to toughen it up? And how many coats is normal? Thanks!

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Sounds like it's not fully cured yet. After 11 coats I'd imagine it might take 3 weeks+ before it will be fully cured. What does the instructions say about coat thickness/cure time? How long has it been drying?

I'm using a water based poly. Are there cure time with water based?

http://www.generalfinishes.com/finishes/wa...thane_Top_Coat_

There was nothing about coat thickness. Normal dry time is 2-4 hours. 8-10 hours in non ideal conditions. Been in my 70 degree house the whole time. Nothing about cure time on website or can. I put the first 3 coats on 4/28, coats 3-6 on 4/29, coat 7 on 5/1, coat 8 on 5/4, Coats 9-10 on 5/5 and coat 11 5/6.

Thanks!

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Consider 14 a minimum. Let it dry until you can't dent it with your thumbnail. Assemble it any sooner than that and you'll damage the finish when you start tightening the nuts and bolts on your bridge, tuners, pots, etc.

It's always good to allow as much dry time as possible before sanding/buffing and final assembly.

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You might have to wait longer than normal now because you applied additional coats before the previous coats had a chance to cure. When I used poly clearcoat I usually waited about a week before scuffing and reshooting.

+1

Too many coats too close together, you can get away with it on nitro, but on can cheap poly no! It will never dry complete! Happened to me and it took at least 6 months to get to the point that I could put the guitar together without marking it, after that it dried completely but shrinked like crazy... if you can remove the finish and start over! Use nitro this time!

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Thanks for all your help guys.

Except for Maiden. You really didn't help at all. Do you really think I care about you're Nitro is better blah, blah?

I applied coat 12 last night and I think I'm gonna leave it hung up for at least a month; let the waiting begin.

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Well, the "nitro instead of poly" advice isn't really something everyone will follow. Lots of people do fine with poly or other non-nitro finishes. BUT, *if* the information is correct that you shot too soon between coats, you might have more problems in the long-term than you want to think about.

*If* another independent source or two can confirm that you're doomed from shooting too soon without curing in-between, there might be SOME merit to the idea of starting from scratch. I can't be that source, not having enough experience, but the information presented DOES set off a few alarm bells.

Greg

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WOW, I'm flattered!!! I guess that the little experience I got count for nothing when I give advise!!! :D

Look here grasshopper!!!

DSC01188.jpg

DSC01038.jpg

This guitar was finished with Duplicolor poly. And this picture is after 7 months after the last coat was on. I could still dent the paint with my fingernail after I polished it. Same for this one!

http://img.photobucket.com/albums/v195/Maiden69/DSC00812.jpg

Like you I blew off anyone that posted that I had made a mistake by shooting too many coats too soon. Well, needless to say, when that LP dried completely it look like the skin of an orange, and as you can see in the picture, it was smooth as glass once I polished it!

After thta Iturned away from poly and finished everything else in nitro. It is ready available on spray DEFT, but this is an inferior quality and not very durable (all my guitars that were shipped got marks from the case inside) or you can buy the quarts from Stew Mac, and use a preval to shoot it. Like this 2

http://img.photobucket.com/albums/v195/Maiden69/DSC03377.jpg

http://img.photobucket.com/albums/v195/Maiden69/DSC03034.jpg

But, this will be my last post here, just to enligthen you, take it or leave it, is your guitar, and it was your hard earned money (I hope) that bought it!

:D

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Remember here guys that "poly" is a very general term when it comes to finishes, at least on this board. God forbid someone find this thread someday and get them confused. The poly you two are/were using is polyurethane, which air dries. The "poly" used on production guitars is polyester based and catalytically cures. I use polyester and w/ proper UV lighting, can have a fully cured finish in a day or two, after putting 10 medium-wet coats on with maybe 10 minutes between. Plus it's as hard as a rock and as clear as water.

Anyhow, the way maiden presented that information may have sounded harsh, but I'm sure it wasn't meant that way. Maiden just likes his exclamation marks a little too much. As I see it you probably have 2 choices: 1)wait a few months to find the finish is in fact not curing and needs to be stripped off, or 2)strip and refinish the guitar now and have it completely dried in a month or two.

peace,

russ

Edited by thegarehanman
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WOW, I'm flattered!!! I guess that the little experience I got count for nothing when I give advise!!! :D

Look here grasshopper!!!

DSC01188.jpg

DSC01038.jpg

This guitar was finished with Duplicolor poly. And this picture is after 7 months after the last coat was on. I could still dent the paint with my fingernail after I polished it. Same for this one!

http://img.photobucket.com/albums/v195/Maiden69/DSC00812.jpg

Like you I blew off anyone that posted that I had made a mistake by shooting too many coats too soon. Well, needless to say, when that LP dried completely it look like the skin of an orange, and as you can see in the picture, it was smooth as glass once I polished it!

After thta Iturned away from poly and finished everything else in nitro. It is ready available on spray DEFT, but this is an inferior quality and not very durable (all my guitars that were shipped got marks from the case inside) or you can buy the quarts from Stew Mac, and use a preval to shoot it. Like this 2

http://img.photobucket.com/albums/v195/Maiden69/DSC03377.jpg

http://img.photobucket.com/albums/v195/Maiden69/DSC03034.jpg

But, this will be my last post here, just to enligthen you, take it or leave it, is your guitar, and it was your hard earned money (I hope) that bought it!

:D

I agree that Deft is inferior for guitar work. Works nice for cabinets though. But must be allowed to dry completely. 2 weeks min and only 3 to for good wet coats. Now as far as the water based poly. I have found that most polys require at least 1 day between coats and at max use only 6 coats if brushed or sprayed at medium thickness. The last coat needs to sit at least 2 weeks before finish. Just my .02cents of cabinet making and finish over the past 20 + years

personally a good shellac finish is better in my opinion , if it was good enough for Stradivarius it must be good enough for me. LOL:)))

MK

Edited by MiKro
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Remember here guys that "poly" is a very general term when it comes to finishes, at least on this board. God forbid someone find this thread someday and get them confused. The poly you two are/were using is polyurethane, which air dries. The "poly" used on production guitars is polyester based and catalytically cures. I use polyester and w/ proper UV lighting, can have a fully cured finish in a day or two, after putting 10 medium-wet coats on with maybe 10 minutes between. Plus it's as hard as a rock and as clear as water.

Gets way more complicated than that. The TS stated he used a waterbased 'poly', which may be polyurethane, may be a varnish, etc. Production instruments sometimes use Polyester (catalzyed chemically, or by UV light), sometimes use catalyzed polyurethanes, but pretty much always use 2-part products, not consumer grade stuff that's generally not suitable for most instruments. The small shop guys I know of that use Polyester use McFaddens, kicked chemically, and rarely shoot more than 2 to 4 coats, total, within a day, and can buff the next.

In terms of waterbased stuff, I've had pretty good luck with Target Coatings products (USL, and others have used their EmTech conversion varnish with success), others like KTM-9, but none are quite as 'hard' as a 'real' poly finish. Rustin's plastic coating (for those on this side of the pond) also has a good track record, and is an alkyd catalyzed 2-part finish. My experience with the waterbased stuff is that you need to shoot LIGHT coats, let it dry enough between coats, and let it cure at least as long as nitro. It's less forgiving when it comes to drips, spills, etc. and isn't always as hard (although nitro's not exactly rock solid or anything). Nitro's probably the most idiot-proof high gloss finish you can find, easiest to repair when still fresh, easy to fix up, easy to buff to a shine, very forgiving of suboptimal spray schedules and conditions, in a way waterbased products, in my experience, simply aren't.

Nitro is nasty stuff (well, the thinner, mostly); poly's even nastier, but not really in a volatile substances way, generally. Waterbased stuff still contains toxic solids and still requires respiratory protection, but at least cleanup isn't quite so carcinogenic.

Seriously, if I could find a vendor who would sell me chemically kicked polyester, I'd go for it in a heartbeat. Until then, I'll stick to Rustin's and the occasional Target/KTM guitar (still have some in stock, and have yet to use Rustins on an instrument, but test panels look promising. Very promising).

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That's quite a reply.... Anyhow, two part, water based polyurethanes are far from perfect at the moment, though the trend seems to be that the automotive industry wants to make the switch as soon as possible(ie as soon as they'll take the beating that the current finishes take) to make the EPA happy...or to get them off their backs. I'd like to give the current products a try, but so far I've only found the leading brands in unusably large cans. I'm well aware of the different varieties of polyesters, vinylesters and polyurethanes etc. out there. I've sprayed many varieties of two part clears and gelcoats, some in worse conditions than I'd prefer... :D My main point was that the two part stuff is not going to yield these problems from putting it on too fast. If you manage to get the surface film to cure too quickly, which is admittedly quite hard, with two part products, you'll likely get bubbles.

chemically kicked...that's new slang to me. i dunno, i've always been fond of "catalyzed."

Actually...I think I'm trailing off. What were we saying? Oh yes, STRIP IT AND START OVER

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