Official Luthiers Forum!
http://www.luthiersforum.com/forum/

finish problem/question
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=36885		 Page 1 of 1
Author:  coach [ Thu Jun 21, 2012 3:58 pm ]
Post subject:  finish problem/question
Hey guys,

Hoping for some advice. :) Here's my problem:

I was having trouble with my spray gun on day 1. Spent the whole day spraying finish with mostly air because I didn't realize the resevoir vent hole was clogged. So I sprayed 7 coats, but all were very dry, pebbly looking, thin coats. Day 2, I figured out my problem, unclogged the vent hole, and sprayed 6 really good coats. Before I sprayed, I level sanded the day 1 coats, but not perfectly; I thought my second day of spraying would cover it up. I also sprayed the entire guitar with alcohol because I read it helps the KTM adhere better.

I waited 2 weeks and started level sanding, or tried to anyway. I couldn't seem to get it perfectly level, so to be honest I became impatient with it and started buffing it out with a medium buffing compound on my buffing assembly. Well, it looks much better than my third guitar, which I buffed by hand, but I still have this grainy look, although it's nice and shiny.

My question is: Should I continue with the medium buffing wheel? My intuition, since I really don't have a clue, thinks I should continue because the grainy look seems to get less and less each time I do. However, I also fear I'm going to go through the finish. Any help would be greatly appreciated. Here's some pics:
Author:  Ken C [ Thu Jun 21, 2012 4:05 pm ]
Post subject:  Re: finish problem/question
Coach, When I shoot Target's water based lacquer, I lay down 9 to 12 coats on the top, which sounds about like what you have. I level with 800G sterated paper using a hard rubber sanding block. I sand until there are no shiny areas. Then I sand to a few finer grits and buff.

That finish needs to be leveled good and you may need to go as low as 600G to level it. I usually level after a half dozen coats using 600G. My final top coats go down pretty well, so leveling the final coats with 800G is fairly easy. The key is getting that first leveling job level! You do not want a shiny spot anywhere on the surface prior to buffing.

Ken
Author:  WudWerkr [ Thu Jun 21, 2012 4:08 pm ]
Post subject:  Re: finish problem/question
Quote:
That finish needs to be leveled good and you may need to go as low as 600G to level it. If you have a fairly thick coating, run through some finer grits then try buffing again. If you only have a half dozen coats down, level it with 600G being very careful not to sand through, shoot another half dozen coats now you have your gun problem figured out, level with 800G, then final sand and buff.


+1 [:Y:]
Author:  Fred Tellier [ Thu Jun 21, 2012 4:11 pm ]
Post subject:  Re: finish problem/question
Go back and do some more sanding, the amount of buffing to remove the pebble look will take forever. I always do a trial buff to see what I am getting and often go back a couple grits and sand more. Leveling takes a lot of patience, the finish is directly proportional to the effort.

Fred
Author:  coach [ Thu Jun 21, 2012 4:35 pm ]
Post subject:  Re: finish problem/question
Thanks for the replies guys. If I happen to sand or buff through, is it possible to re-spray? Would I just rough it up with a scratch pad and spray some alcohol on it and then spray?
Author:  jac68984 [ Thu Jun 21, 2012 9:05 pm ]
Post subject:  Re: finish problem/question
coach wrote:
Thanks for the replies guys. If I happen to sand or buff through, is it possible to re-spray? Would I just rough it up with a scratch pad and spray some alcohol on it and then spray?


Assuming you don't have any color-matching issues upon sanding through, wipe scuff lightly with 400-600 grit, wipe with alcohol, and reshoot the affected area, ensuring a good overlap with the surrounding finish.
Author:  Fred Tellier [ Thu Jun 21, 2012 9:27 pm ]
Post subject:  Re: finish problem/question
As long as you do not go past the shiny spots and don't hit the sharp edges you should be safe. You are removing excessive thickness of the high spots to even things out. Even if there is a little roughness it will look much better than where you are now. I have finished 15 guitars so far and still improving my process and results, I think if I ever get it totally figured out I will get bored with it. My latest is a black top and that has been a real bear to get right, I will post pictures of it by this weekend.

Fred
Author:  coach [ Thu Jun 21, 2012 11:29 pm ]
Post subject:  Re: finish problem/question
Fred Tellier wrote:
As long as you do not go past the shiny spots and don't hit the sharp edges you should be safe. You are removing excessive thickness of the high spots to even things out. Even if there is a little roughness it will look much better than where you are now. I have finished 15 guitars so far and still improving my process and results, I think if I ever get it totally figured out I will get bored with it. My latest is a black top and that has been a real bear to get right, I will post pictures of it by this weekend.

Fred


Fred,

If you're refering to the bloodwood guitar on your website...dude that is one beautiful guitar! I love it. Thank you for all your advice. I know you're right. I just spent some time, about an hour and a half, sanding with 600 grit and a block, and got it alot closer. I was afraid to go any further, I still had a few tiny shiny spots, and stopped and started buffing again just to see where I was at. Wow what a difference! I think I'm going to attack it again tomorrow with the sand paper one more time. I want as close to perfect as I can get. This is for my daughter's 16th birthday, and it's really special for me to get this right.

You know what's the craziest thing about this luthier stuff? Waiting to hear what it will sound like! I can't wait to hear this guitar!

Thanks again.

Sean
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/