Finishing Experiments

Questions and answers for beginners. If you have a question, so do most other people.
scamp
Posts: 63
Joined: Sat Mar 26, 2022 8:19 pm

Finishing Experiments

Post by scamp »

Getting close to the finishing stage of my first guitar build.
After some investigation I think it probably makes sense to try the Tru Oil method.
Seems like good results with minimal experience required.

I would like to try out the Tru Oil finishing technique on something other than the finished guitar to gain experience and see how I like it.
Ideally I would like to try it out on similar woods ( rose wood and spruce ) as similar to the guitar as possible.
Unfortunately, I don't have any scrap to play with.

Does anyone have any suggestions on where to get some rose wood / stika spruce scrap to play with or possible other easily available woods that would work for my experimentation without costing an arm and a leg?

Thanks
jread
Posts: 393
Joined: Wed Feb 13, 2019 9:52 am

Re: Finishing Experiments

Post by jread »

I bought some mandolin sized sitka at alaskawoods.com for under $10 when I wanted scrap. I ended up using a lot of it for center strips later. I bet the suppliers would have scrap or orphaned pieces if you call them. RC tonewoods, Exotic Wood Zone, etc.
Diane Kauffmds
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Joined: Sun Mar 09, 2014 8:13 pm

Re: Finishing Experiments

Post by Diane Kauffmds »

Do you have off cuts from building? Are you pore filling?

LMII sells orphan pieces, but I'm not sure you can specify species.
Last edited by Diane Kauffmds on Fri May 13, 2022 11:17 am, edited 1 time in total.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
Diane Kauffmds
Posts: 2714
Joined: Sun Mar 09, 2014 8:13 pm

Re: Finishing Experiments

Post by Diane Kauffmds »

Instead of rosewood, which has gotten expensive, you could just use a hardwood with pores to gain experience with the TruOil. If you pore fill, there are several methods. All work. I think Aquacoat is probably the easiest.

You would seal your sides/back with a finish (spruce doesn't need pore filling). I use a couple of coats of 1# cut shellac. Allow to set up well, then just rub in a thin coat of Aquacoat. Allow to dry. Sand to level. Repeat as many times as it takes to fill the majority of the pores. In rosewood 3-4x is usually enough. You only use a small amount per coat.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
MaineGeezer
Posts: 1483
Joined: Wed Aug 13, 2014 12:14 pm

Re: Finishing Experiments

Post by MaineGeezer »

Agree -- the species of wood isn't particularly important so much as the surface texture. What you need to get experience with is filling the grain and getting good surface prep. Putting on the Tru-Oil is easy once you get the surface prep done.

In case you aren't aware, Tru-Oil cures in the presence of oxygen. This has a couple of implications. One, a rag soaked in Tri-Oll is the classic "oily rag" that can heat up and spontaneously combust, at least in theory, so be careful where you put used materials. Two, the stuff reacts with the oxygen in an opened bottle and will skim over or possibly solidify. One idea I've heard for dealing with that problem is to take a propane torch (unlit!) stick it in the bottle, blow in a bit of propane -- thereby blowing out the air and oxygen -- and quickly put the cap on. FWIW...
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
carld05
Posts: 135
Joined: Mon Mar 19, 2012 4:19 pm
Location: Forest Ranch, CA

Re: Finishing Experiments

Post by carld05 »

I got this stuff for that. Ain't gonna go BOOM!! https://www.amazon.com/Bloxygen-Preserv ... 687&sr=8-2
scamp
Posts: 63
Joined: Sat Mar 26, 2022 8:19 pm

Re: Finishing Experiments

Post by scamp »

As always, thanks for the suggestions/input.

Unfortunately I don't have any off cuts from the build.
I think I will seek out some easily available wood with some open pores to practice pore filling and then Tru Oil application. Maybe some oak or similar.

I knew that Tru Oil produced an exothermic reaction when exposed to oxygen ( I will indeed be careful as my neighbor set his garage on fire with rags soaked in linseed oil ). I wasn't, however, aware of the problem with an opened container allowing oxygen to make the Tru oil skim over. I will indeed buy the non-boom (Bloxygen) solution to this problem.

A few questions I have about the finishing issues that were brought up.

1) What level of sanding preparation is best before starting the pore filling/finishing? Some say sand to 220 grit. Some say finer .... 320....400 etc. John H indicated that going finer than 180/220 would burnish the surface and cause problems ( I assume with finish adherence ). Is this true with Tru Oil ? Currently the sides and back of my guitar is rather smooth as a result of the scraper used to level the binding ( which also scraped the rose wood smooth). I was thinking of doing the top with 150 and then 220. Some say to sand the 220 against the grain to reduce the ripple effect of sanding with the grain. The sides and back with 150 and 220 with the grain.

2) I watched a good video on Tur Oil finishing based on a technique from Eric Schafer ( https://www.youtube.com/watch?v=UvLL9fzHvRU ). He didn't use shellac just Aqua Coat. Is the shellac necessary and why? Also, I assume you mix your own shellac with shellac flakes and 190 proof denatured alcohol ( ethyl alcohol ). Also, I assume you don't need the shellac on the Spruce top.

3) If you use shellac, do you sand it after it cures between coats and before the Aqua Coat? If you do, what grit? 220?

4) What sanding do you do between Tru Oil coats? 0000 steel wool?

Thanks
tippie53
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Location: Hegins, Pa
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Re: Finishing Experiments

Post by tippie53 »

shellac I use flakes and make my own
zinzer ultra clear dewaxed NEVER USE WAXED
one coat NO SANDING apply filler
another Shellac Scuff sand 320
then finish on top
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
scamp
Posts: 63
Joined: Sat Mar 26, 2022 8:19 pm

Re: Finishing Experiments

Post by scamp »

tippie53 wrote: Sat May 14, 2022 6:32 am shellac I use flakes and make my own
zinzer ultra clear dewaxed NEVER USE WAXED
one coat NO SANDING apply filler
another Shellac Scuff sand 320
then finish on top
To be clear, you are saying...

Make my own shellac using dewaxed flakes and denatured alcohol
Put on one coat shellac and don't sand.
Apply filler ( I would assume you sand each filler coat with 220 grit )

And this is where I'm confused...
You said ... " another Shellac Scuff sand 320"

Are you saying to apply another coat of shellac over the pore filler and scuff with 320 before applying the Tru Oil?
tippie53
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Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
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Re: Finishing Experiments

Post by tippie53 »

yes
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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