Sap?

The Achilles' Heel of Luthiery
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aaron
Posts: 24
Joined: Thu Feb 21, 2013 4:13 pm

Sap?

Post by aaron »

Hello all! I've been finishing my second guitar this week with tru oil. The back and sides are Rosewood and the top is spruce. The challenge I have come across is that for the most part the finish is looking great except there are some places on the sides where it looks like Sap or something is coming through. The finish resists it and it is a little sticky even. What should be done?
tippie53
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Re: Sap?

Post by tippie53 »

what kind of wood ?
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
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B. Howard
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Re: Sap?

Post by B. Howard »

Must resins and sap can be cleaned off with DA. You may need to scrape back the finish around it a bit to clean it up at this point.
You never know what you are capable of until you actually try....

Brian Howard
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tippie53
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Re: Sap?

Post by tippie53 »

DA Denatured Alcohol
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
aaron
Posts: 24
Joined: Thu Feb 21, 2013 4:13 pm

Re: Sap?

Post by aaron »

Thanks guys. I may try the DA route. Should I just rub it on the trouble spots or is there a more effective technique you have used?

John, the wood is rosewood. And the problem areas are only on the sides, not the back which is also rosewood.
tippie53
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Re: Sap?

Post by tippie53 »

it is not unusual for rosewood to emit a resin during the bending process. While this normally is sanded off , there may be condensed pockets. I would just clean up the bad area and see what it looks like.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
mjmeehan
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Location: Bethlehem, Pennsylvania

Re: Sap?

Post by mjmeehan »

I had a similar problem with tru oil over rosewood. I found it necessary to sand back to the wood, apply a layer of shellac, then proceed with the tru oil. It worked well and I have used this process many times since.

I figured that the tru oil didn't cure fast enough over oily wood and allowed the oils to mix. The shellac formed a barrier between them. That's a guess, though. All I know for sure is that it worked. Good luck.
glasalle1
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Joined: Sun Aug 22, 2010 5:02 pm

Re: Sap?

Post by glasalle1 »

My method for Tru oil is:

- Pore fill with Z-poxy
- Seal with Shellac
- wipe Tru Oil on thinly with the grain
- Wipe it off with the grain
- Put on 12-15 coats (up too 2 coats a day)
- if required, I "level sand" with 0000 wool every 4 or so coats (gently!)
- when done, let cure for 2 weeks
- Buff out with Micro mesh from 3000 thru 12000
- hand polish Meguirs swirl remover
- Meguirs #7

Glenn
aaron
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Joined: Thu Feb 21, 2013 4:13 pm

Re: Sap?

Post by aaron »

Thanks guys! The DA is working... Slowly. Next time I will use the shellac first. But this time I think I can make it work. I'm pretty happy with this one so far. I should be stringing it up soon!
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