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Sap?
Posted: Sun Jan 19, 2014 10:24 pm
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?
Re: Sap?
Posted: Mon Jan 20, 2014 7:57 am
by tippie53
what kind of wood ?
Re: Sap?
Posted: Mon Jan 20, 2014 8:20 am
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.
Re: Sap?
Posted: Mon Jan 20, 2014 10:38 am
by tippie53
DA Denatured Alcohol
Re: Sap?
Posted: Mon Jan 20, 2014 12:04 pm
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.
Re: Sap?
Posted: Mon Jan 20, 2014 2:44 pm
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.
Re: Sap?
Posted: Wed Jan 22, 2014 11:26 am
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.
Re: Sap?
Posted: Wed Jan 22, 2014 1:17 pm
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
Re: Sap?
Posted: Wed Jan 22, 2014 8:46 pm
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!