When to drop fill?

The Achilles' Heel of Luthiery
MKlee
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When to drop fill?

Post by MKlee »

I just completed the pore filling process (4 coats) on my first guitar and I'm ready to start spraying rattle can lacquer. However, on the sound board (sitka spruce ... NOT pore filled) I noticed a scratch running with the grain that I hadn't noticed before.

I have already sprayed 2 coats of vinyl sealer and 1 coat of lacquer on the soundboard to protect it during the pore filling of the back and sides. Should this scratch fill-in during finishing the soundboard OR would it be better to drop fill it before applying the finishing coats? I'm planning on 10 - 12 coats of lacquer. The scratch is about 1 1/2 inches long and barely catches my fingernail when dragged across it. It can't be seen unless held up to a bright light. My wife thinks I'm insane!

Mark
Mark Klee
Mark@HeartForAfrica.org
Swaziland, Africa
kencierp

Re: When to drop fill?

Post by kencierp »

No amount of finish or drop filling (which is done after almost all the finish applied) is going to cover up or hide a scratch. Actually more finish layers will more often then not make the scratch stand out - amplify! So to do it right you need to sand everthing back (off) and remove the scatch, re-sand with progressive grits and start your finish application over. $.02
Tony_in_NYC
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Re: When to drop fill?

Post by Tony_in_NYC »

Ditto what Ken said. No amount of lacquer will disguise a scratch. You will see it every time you look at the guitar even if it is barely noticeable. It will be a big neon sign to you even if others barely notice it. Fix it right and you will be happier in the long run.
MKlee
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Joined: Mon Feb 14, 2011 10:31 pm
Location: Swaziland, Africa

Re: When to drop fill?

Post by MKlee »

Okay, I'll sand it back and restart ... uggghhhh.

Just for clarity ... why won't the lacquer fill the voids??? When I went into my local Woodcraft store they all thought I was crazy for even using pore filler ... without exception, they ALL said I just ought to use the lacquer and sand back - no need for pore filler.

I've finished many wood projects (furniture) with Poly and it worked like a dream ... just wondering the difference.

Mark
Mark Klee
Mark@HeartForAfrica.org
Swaziland, Africa
MKlee
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Joined: Mon Feb 14, 2011 10:31 pm
Location: Swaziland, Africa

Re: When to drop fill?

Post by MKlee »

BTW, I'm not even sure it's actually a "scratch" as much as an indentation ... I'm assuming the resulting corrective action is the same.
Mark Klee
Mark@HeartForAfrica.org
Swaziland, Africa
Kevin Sjostrand
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Re: When to drop fill?

Post by Kevin Sjostrand »

Hi Mark
I am not the expert here, Ken and John are, but just for clarification: it sounds like you don't think the scratch is in the spruce, just in the finish?
Ken, John. Correct me if I'm wrong here okay!

If it is in the wood, then you have to sand it out. If it were in the finish, you should be able to apply more lacquer and just build it up......however.....with the amount of lacquer you have on there, if you can feel it, then I doubt it is only in the finish. You would have to have a pretty good build up for the scratch to only be in the finish, so I sounds like you are going to have to sand it out.

Kevin
tippie53
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Re: When to drop fill?

Post by tippie53 »

I do not sand with the grain on the final sanding and never with the grain on finishing. I like to do circles and light touch. I agree is the scratch is in the finish you may be able to hid it but it is best to sand it back at this point for best results
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Ben-Had
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Re: When to drop fill?

Post by Ben-Had »

If it turns out to be a "slight" indentation what about steaming it out?

Tim B
Tim Benware
tippie53
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Re: When to drop fill?

Post by tippie53 »

if your scratch is in the wood , the sanding should be in an area large enough to repair it. Then as you finish , the layers should be totally thick enough to allow you to level sand it and all will be well.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
MKlee
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Joined: Mon Feb 14, 2011 10:31 pm
Location: Swaziland, Africa

Re: When to drop fill?

Post by MKlee »

I believe it's in the wood and NOT just the finish, the finish around it looks fine. It is very small almost like the wood was scratched with a needle. At first I thought it was a hair in the finish, but it's definitely a scratch.

Are you guys saying to sand it out only at the location of the scratch? I was thinking I'd need to sand the entire soundboard down?

I thought about steaming, but that only works on bare wood doesn't it?
Mark Klee
Mark@HeartForAfrica.org
Swaziland, Africa
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