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 Post subject: French Polish Repair
PostPosted: Wed Jul 09, 2008 4:14 pm 
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Contributing Member
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Joined: Tue Nov 21, 2006 4:02 pm
Posts: 801
Location: United States
First name: Gene
Last Name: Zierdt
City: Sebastopol
State: CA
Zip/Postal Code: 95472
Country: USA
Focus: Build
Status: Amateur
I'm working on my first french polished guitar. It's coming out fine, except for
one spot on the top where I went back after the first finish sessions, and sanded
out a shallow trough from a scraper. Now I'm having a devil of a time matching
that area to the rest of the top. It's an oval, roughly 1" x 3/4", and I can't get
it to blend in with the rest of the top. What seems to be happening is that I can't
get the thickness of that small area back up to match the rest of the top. I get
a consistent level change (thicker) around the periphery, and the area around
the patch is slightly darker- because the film is thicker, I believe. I've tried just
bodying that section, but it's too small. Stiffing-off with almost pure solvent helps
a little, but the repair still shows. Is there a trick to blending in a small area like
this, or do I have to strip the top?

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain


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 Post subject: Re: French Polish Repair
PostPosted: Wed Jul 09, 2008 4:29 pm 
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Joined: Mon Mar 19, 2007 7:05 am
Posts: 9191
Location: United States
First name: Waddy
Last Name: Thomson
City: Charlotte
State: NC
Focus: Build
Status: Semi-pro
I want to see the answer to this too. I hope Michael will chime in here.

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 Post subject: Re: French Polish Repair
PostPosted: Wed Jul 09, 2008 4:35 pm 
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Old Growth Brazilian
Old Growth Brazilian

Joined: Tue Dec 28, 2004 1:56 am
Posts: 10707
Location: United States
Yep you have got the only real hard FB repair there is. the reason it build at the edges as you body that area is the that the new film is being push out to the periphery because the muneca is not really traveling it is just rotating in basically one location.

There is two ways to address this. The simplest is to drop fill very thinly each day and spirit-off as it firms up. It will take 6 or seven fills to get there as you want the to be very sparing with the fill.

Unfortunately the other effective method is to strip and redo the top complete. The fill method leaves less amalgamated area but will not be noticeable, the full strip and body is the best way to go.

One nore thing. If you went into the seal coat you may have issues with color match. If this is the case the full strip and rebody is in order.


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 Post subject: Re: French Polish Repair
PostPosted: Wed Jul 09, 2008 4:45 pm 
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Old Growth Brazilian
Old Growth Brazilian

Joined: Tue Dec 28, 2004 1:56 am
Posts: 10707
Location: United States
Also if you do the fill method be sure your sprit-off session are full body length and over lap the good area, you can have a lighter touch after you pass the affected zone. In fact go a good inch or more past the affected area. As you spiit off you melt and drag a fine amout of shellac so you want to spread this evenly.


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 Post subject: Re: French Polish Repair
PostPosted: Wed Jul 09, 2008 6:03 pm 
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Cocobolo
Cocobolo

Joined: Wed Apr 09, 2008 11:13 am
Posts: 281
Location: Los Angeles
I tried Michael's first suggestion. I found it beyond my abilities. I've decided (that for me) the best thing to do is level and build again.

Please let us know how it goes.

Best of luck to you! If you have to sand, you have my condolences!


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 Post subject: Re: French Polish Repair
PostPosted: Wed Jul 09, 2008 7:01 pm 
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Joined: Tue Nov 21, 2006 4:02 pm
Posts: 801
Location: United States
First name: Gene
Last Name: Zierdt
City: Sebastopol
State: CA
Zip/Postal Code: 95472
Country: USA
Focus: Build
Status: Amateur
Michael, Thanks for the response. I'm seeing exactly what you describe- a ring of material that builds
up around the low area. I even tried stripping the bald spot out to a bigger diameter- about 3 inches
across. I used a very small muneca and found I could do a better job in building up just inside the
thick outer ring, but it was still not up to my standards. I'm going to strip the top- it's just too easy to
do that compared to noticing the problem every time I pick up the guitar...even if most people
would never notice it.

I also made another mistake on this guitar [headinwall] . I glued the bridge down before the french polish was finished.
We had a family reunion and I wanted to show my dad the (almost) finished guitar, so I mounted the
bridge and strung it up. As long as I'm stripping the top, I'm going to pull the bridge also

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Politicians and diapers must be changed often, and for the same reason- Mark Twain


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