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PostPosted: Tue Jul 31, 2012 3:35 pm 
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Brazilian Rosewood
Brazilian Rosewood
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Joined: Mon Dec 27, 2010 9:06 pm
Posts: 2739
Location: Magnolia DE
First name: Brian
Last Name: Howard
City: Magnolia
State: Delaware
Zip/Postal Code: 19962
Country: United States
Focus: Repair
Status: Professional
John Sonksen wrote:

Thanks for this Brian, lots of good info there. I'm going to get a couple coats of lacquer down before I try to get the burst going, hopefully that'll be in the next week. Here's another question, how many coats after the burst color goes on would be a good amount to do a safe buff out with? 5? 8? 10? I'm not accustomed to doing so many coats of lacquer, we're usually a coat of sealer and then a couple coats of lacquer at my shop but obviously we're not cutting and buffing our cabs. Is there anything I should know about laying down so much lacquer? Can I recoat in a few minutes, a few hours or what? I'm a little concerned that if I go too fast with too many coats I'm going to end up trapping solvent under a skinned over topcoat and have problems.

Thank you so much for your help!


If your shop is like mine, you are most likely spraying a high solids acrylic lacquer on the cabs, either a pre or post cat. It may help for you to think of this process more like a glaze than the fogging. Acrylic cat lacquers have higher solids contents, usually around 40%, so two wet coats at 4 mils yeilds 3-4 mils finished. Plenty good for a crosslinked acrylic finish. That is a different finish from pure nitro. Even the high solids nitro from my supplier is only 25% solids at best. So that means if I can hang a coat at 4 mils I will wind up with a 1 mil film build after it is completely out-gassed. I am not sure of the solids content of Behlins lacquer but their tech dept should be able to tell you. Then you can get an idea of how much material you are putting down by how thick you can hang your wet coats. I never want to see more than 8 mils after all is said and done, usually shooting for about 5-6. Burst generally go a bit thicker because of the shade coats in between. I find I lose about 1.5 mils in sanding and buffing, but that can vary greatly depending on how well your coats flow. That is another difference from the cabs, we generally don't level and buff them. My figures are based on amount of material left when it is completely out-gassed. So if you spray a card and measure, your green measurements will be higher. That's why I prefer to do the math and check my spraying with a mill card periodically. No guesswork on how much lacquer will be left at the end and less worries about failures like crazing. Don't forget to account for additional thinners/retarders in this equation. How long between coats depends on a lot of things, but basically you should not be able to leave a finger print in the coat with moderate pressure. About 20-30 minutes works for me, but I like the booth hot.....85 degrees if I can get it.

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PostPosted: Thu Aug 02, 2012 11:29 pm 
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Cocobolo
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Joined: Wed May 30, 2012 11:00 pm
Posts: 498
First name: John
Last Name: Sonksen
City: PORTLAND
State: Oregon
Zip/Postal Code: 97216-2013
Country: United States
Focus: Build
Status: Amateur
so this happened:

Image

as I looked at it more and more I just felt kind of disappointed with the depth of the grain. Whoever said that popping the grain makes for a good photo and not the greatest finish in person was onto something. It took quite a bit of effort, and it's not back to pre-stain perfection, but it's close. There is just a little stain left in some of the deepest parts and once I tone it I think they'll be less noticeable, or at least it'll look more like a naturally occurring inclusion. From here I'm going to spray my color over the top of a couple of coats of lacquer and I hope I'll be happier with the outcome.

Here's what it looks like under a coat of sealer:
Image

I'm glad my top and back were as thick as they are...


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PostPosted: Fri Aug 03, 2012 10:17 am 
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Contributing Member
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Joined: Fri Jun 22, 2012 11:12 am
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First name: Rodger
Last Name: Knox
City: Baltimore
State: MD
Zip/Postal Code: 21234
Country: USA
Focus: Build
Status: Amateur
Sometimes the magic works, some times it does not....

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PostPosted: Sat Aug 04, 2012 7:25 pm 
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Brazilian Rosewood
Brazilian Rosewood
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Joined: Sat May 22, 2010 10:32 am
Posts: 2616
First name: alan
Last Name: stassforth
City: Santa Rosa
State: ca
Zip/Postal Code: 95404
Country: usa
Focus: Build
Status: Amateur
If it makes you feel better,
I've had to grind the finish completely off of 2 guitars,
which had about 10 coats on!
Nice wood!
Looks like the stain soaked into the rolls in the figure.
Good luck!


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PostPosted: Sat Aug 04, 2012 9:18 pm 
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Cocobolo
Cocobolo

Joined: Wed May 30, 2012 11:00 pm
Posts: 498
First name: John
Last Name: Sonksen
City: PORTLAND
State: Oregon
Zip/Postal Code: 97216-2013
Country: United States
Focus: Build
Status: Amateur
alan stassforth wrote:
If it makes you feel better,
I've had to grind the finish completely off of 2 guitars,
which had about 10 coats on!
Nice wood!
Looks like the stain soaked into the rolls in the figure.
Good luck!

Thanks for that Alan, it does!


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