Official Luthiers Forum!

Hey Everyone,

I am spraying a nitro finish, and just noticed that I have a run. I sprayed 5 coats last weekend, and thought I had sanded it out, but it still seems to be there as I am spraying today. Do I have to sand it back to wood, or how do I go about getting it out?

Thank you.

Jeff

Jeff Doty38473.8087615741

Just wet sand it with 280-400 using a block. No need to sand it back to bare wood. I would let it dry for a week or you will have it gum up the paper.

_________________
tim...
http://www.mcknightguitars.com

Hi Jeff,

One of the best tricks I know for removing a run is to scrape it level with a razor blade. for best results wait until the run or drip is well cured. If the drip is still gummy it can tear out, so be dam sure its well cured dammit!

set up your blade with a piece of celophane or thin electrical type tape on either side so the ends wont scratch and center the scrape over the drip.

go slow and good luck

Also if you leave the run to dry wait AT LEAST 3 WEEKS!!

Then and ONLY then can you sand it down, the reason is that a drip will cure slower than the rest of the finish and if you sand it too early it will be flat for a short time and then you get a reverse run because that area still has more gassing off to do.

Don't ask how I know, but trust me on this one :)

In fact I have one of these to sand out tomorrow

Cheers

-Paul-

_________________
-Paul-

Patriot Guitars

Hey guys. I'm having trouble understanding why all the cure time is necessary to fix a run. I don't normally get runs with McFaddens nitro but when I do I just scrape it level with the rest of the finish the next day and then continue with the subsequent coats.
I may be missing something here but seems like if the run is leveled with the rest of the finish that it shouldn't take any longer than normal to cure.
I have, on occasion, wiped a run with my pinky and then continued spraying. This would be on the sealer coats before any color is applied.
Nelson

If you level it right at the start it will be fine, but if you let it cure it will take longer than the rest of the finish because it's so much thicker.

Frank Ford says that if you do drop fills in a cured finish to wait three weeks before you level off or it will continue to shrink and you'll end up with a dip..

-Paul-

_________________
-Paul-

Patriot Guitars

I have knocked off a drip the next day, while its still a bit gummy. Like Paul, I first scuff sand the top of the drip to let it gas out a bit, then I scrape with a very light touch.

I have also actually cut them flush with the razor,but it is very easy to get a tear out doing this so I cant really recommend it.

Paul--what you said on letting a drop fill cure several weeks.
A little off the subject here but, regarding drop fill, do any of you guys (or gals) use CA for drop fills? I've read a lot of pros and cons and probably the most intimidating is that CA and lacquer don't buff to exactly the same sheen.
Nelson

[QUOTE=npalen] Paul--what you said on letting a drop fill cure several weeks.
A little off the subject here but, regarding drop fill, do any of you guys (or gals) use CA for drop fills? I've read a lot of pros and cons and probably the most intimidating is that CA and lacquer don't buff to exactly the same sheen.
Nelson
[/QUOTE]

Nelson,

I use CA to drop fill and it works like a charm. However, I am using catalyzed urethane for my finish.

If I get a run I let it dry for one day in a warm room. Then I take a new razor blade and slice the run right off the surface. Sand it with 400-grit until it’s perfectly smooth and level with the rest off the finish. If it tears when I slice it, I just sand it a little and drop fill with more nitro until I get it level.

Thanks for the help Everyone.

I used a block and 320 this morning and was able to sand it out level. Worked great!

This is my 1st time spraying nitro, and so far I am pretty excited about the results. I have never sprayed anything before, so trying to learn how to use a spray gun, and use lacquer is all new to me. Can't wait to spray the last few coats and then buff it out in a few weeks.

Jeff

Jeff--I can tell you from experience that a few weeks can seem like an eternity when you're excited about buffing out that brand spankin' new lacquer finish.
If you're tempted to jump the gun, remember, we're all here to support you.
Nelson

Hi Nelson,   I have not had good luck with CA drop filling. In fact the few times I have tried it have been disasterous, and I have ended up with a mess on my hands.

I perfer to use lacquer for drop filling, I like to set a small amount out in a jar and let it thicken to the the desired consistancy ( thicker for open wounds and thinner for thin lines).
This works great, I have been able to build it up to level low spots like where the pearl is slightly under flush.

Matt