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I cracked My Finish! finally...
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=14219		 Page 1 of 1
Author:  Dave-SKG [ Wed Oct 24, 2007 11:40 am ]
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In a previous thread I briefly discussed the need i have to crack the finish on an electric guitar I am building for a customer. I don't think I will have any problem with the body because I sprayed it with nitro. I am curently letting it harden so I can crack it. The problem is with the neck. The neck was purchased on ebay and apears to be a fairly current model. I sprayed it with antique amber nitro and then scratched, chiped, stained, burned, and wore down the back of the neck in all the spots you would expect. THE PROBLEM came when I tried to crack the finish...first I tried the air duster upside down method...no good...next in the freezer for 15hrs...no good...next dry ice...2-3 hrs...nadda. This finish, which I assume is Poly from Fender (it's a fender american neck) just won't crack...any suggestions?


It's unbelievably tough!


Any/all help is greatly appreciated.


Thanks,


Dave


 
Author:  Rick Turner [ Wed Oct 24, 2007 12:09 pm ]
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Cryognic treatment...maybe...

Fuggedaboudit. Strip it, do it in nitro, crack it.

Let's see...go to a funky auto junk yard and puncture the compressor lines on an old auto air conditioning unit?   Not PC...but it'll do it...
Author:  David Collins [ Wed Oct 24, 2007 1:57 pm ]
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If rapid, drastic temperature change doesn't do it, it could just be a really
flexible finish. One of the goals of finish makers over the years has been
to make finishes that will resist cracking, while trying to keep it hard and
dent resistant. You may very well have one of the better "new and
improved" finishes on your neck. I've never tried crazing a modern poly,
but if after 15 hours in the freezer it didn't crackle like mad the second it
hit room temperature, you may have an uncrackable finish. The canned
air is even colder and drastic, and I'm surprised that didn't do anything. If
it was going to crack, I would think that even if you didn't see cracks you
would have heard it.

I wish I had some better ideas, but I think Rick may be right. If it won't
crack, there may not be any easy way other than refinishing it in nitro.
Good luck, and let us know if anything does end up working.
Author:  Wayne Clark [ Wed Oct 24, 2007 2:22 pm ]
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[QUOTE=Rick Turner] Cryognic treatment...maybe...

Fuggedaboudit. Strip it, do it in nitro, crack it.

Let's see...go to a funky auto junk yard and puncture the compressor lines on an old auto air conditioning unit?   Not PC...but it'll do it...[/QUOTE]

Here is a more PC suggestion. If there is a university nearby, contact the physics or chemistry department. They would likely have access to liquid nitrogen. Just thinking back to my college days, I would have fixed you up for the price of lunch or a pitcher of beer.

Author:  SniderMike [ Wed Oct 24, 2007 5:09 pm ]
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Have you tried the dry ice yet?
Author:  Dave Rector [ Thu Oct 25, 2007 12:32 am ]
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Dave, maybe you could try hitting it with a blast from a heat gun immediately after removing it from the freezer. Faster temp change might help.
Author:  Dave-SKG [ Thu Oct 25, 2007 1:51 am ]
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Thanks for the suggestions everyone. Liquid Nitrogen did occur to me but I am affraid it will also affect the wood too much...Rick's idea about old auto refrigerant is probably the answer except I doubt I'll find any here in Sarasota...


The only reason I didn't completely strip the neck and spray nitro was that I wanted to prserve the Fender Logo and the serial Number .


I guess I don't have a choice...I tried everything including hitting it with an extremly hot heat gun right out of the freezer. Even tried laying it out in the hot Florida sun (95deg)straight from the freezer. N.G.


Science is amazing isn't it?!


Worst part is, with all the other wear and tear treatments that I did to it, the  neck does look authentically old...just missing those cracks..


Well maybe I can find some old freon cans somewhere...?
Author:  grumpy [ Thu Oct 25, 2007 2:51 am ]
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If it makes you feel batter, necks don't often craze anyhow, at least not to the degree that acoustic bodies do, due to their mass.

On the more helpful front, try freezing it to colder temps, and for a longer period. Your freezer isn't -that- cold.  Find a way to get it past -50 or so, and leave it there a few days, then expose it directly to the hot afternoon sun, immediately.

Also, a fresh finish, even nitro, is much more flexible and able to withstand temperature swings than a fully cured finish. Give it time, if you can. Fresh nitro over a cured nitro finish will be very flexible for a few months and unlikely to craze easily.
Author:  Dave-SKG [ Thu Oct 25, 2007 5:37 am ]
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Thanks "grumpy". I think I'll try lashing the dry ice to it while in the freezer. I think the problem is, however, that fender has come up with some super poly finish that doesn't crack...I may have to sand it down and re-finish...or maybe I'll just crack it over the customer's head...just kidding
Author:  Dave-SKG [ Fri Oct 26, 2007 1:55 pm ]
Post subject: 

Well,


I think I have it...it's cracked/crazed...I listened to the advice of the great minds here at OLF and concluded that I must not be getting the finish cold enough. So I bought more dry Ice and this time sandwiched the headstock between two large chunks of the dry ice ( I put the DI in zip lock bags first and then left a  small opening for the gas to escape). Left it on Ice for 4 hrs. It got so cold that there was frost on the bottom of the table it was sitting on. So then I figured why not give it a little assistance and tap the headstock with my soft head fretting hammer...The finish cracked...I then used a heat gun dried/heated it quickly and traced the cracks with a sharp new razor...re-froze the headstock and did it again...more cracks...but you really had to look for them under a strong light at the right angle...again taced with razor (lightly) re-froze and tapped some more...this time I took some nice medium brown soil from my daughters garden and rubbed it into the cracks...They look pretty good. I think the customer is going to be happy...and that's all that matters right? I'll take some pics and post if they show anything well enough.


Thank You everyone who gave advice. I appreciate your help.


Dave
Author:  Dave-SKG [ Fri Oct 26, 2007 2:17 pm ]
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Some pics...


 


 





 
Author:  KenH [ Fri Oct 26, 2007 3:09 pm ]
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Dave, you come up with some weird stuff my friend. As hard as I try to perfect finishes and keep them from cracking.... here you are happy because you got yours to crack.  Makes a guy wonder....



By the way, I got all my stuff you sold me on the swap. Thanks for the great deals!
Author:  grumpy [ Fri Oct 26, 2007 3:41 pm ]
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Way cool! Glad the dry ice worked. Where I live, all i need to do is wait for winter <bg>

But if you would have asked, i'd have told you to stop when the cracks were barely visible, and not use the knife. Once the finish has split, repeated warming/cold cycles accentuate the crazing naturally. While your work came out very nice, it may have appeared more natural if no knife had been used.

that said, we all forgot to mention that one trick that antiquers use is to use a sharp knife to extremely lightly score the finish, -before- doing the deep freeze/heat cycles. That way, they force the cracks/crazing to eares that would have them first.

Also, the dirt is overkill. Natural body oils(rub your forehead, the side of your nose, whatever, with a finger and rub -that- into the cracks0 lends to a more natural, subtle look that will age correctly in the years to come. Not sure how the dirt will age...

That said, your work turned out very well(the above is fodder for the next time). well done!
Author:  K.O. [ Fri Oct 26, 2007 3:51 pm ]
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Methinks ye hev crecked mon!


Knew I was in the right place.

anutter bit plum in me ed.


Tanks I tink?

                K.
Author:  Dave-SKG [ Sat Oct 27, 2007 5:15 am ]
Post subject: 

 


Thanks Ken, I hope they work well for you.


Mario, many thanks as well. I know...after all that...I looked at it and said the front is better because I didn't do the "trace" part. The back looks like overkill...intentional...I know...But like you said I'll know better for next time. I am sure the customer will be happy with the results as the guitar he wants to duplicate is really beat badly and the more natural, subtle look wouldn't havve satisfied as much.


I was going to ask you...it must be getting cold up there already. Next time I ship the neck to you and you can just stick out side for a day and it will be perfect.


Another wierd note...if you noticed the "chip" on the h.s....I did that by hitting the h.s. with a real hot heat gun...it bubbled the finish...the finish dried, cooled, and then was very brittle...a little finger nail action pealed/cracked it right off. So much for the "tough" Fender finish...


Thanks Again everyone!
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