Nitro on top of Truoil

jonnyschanny · #1 05-17-2018, 12:56 PM

Hi all. I've got my guitar basically done now...however the finishing has been pretty bad. Uneven. I think my truoil got a bit too thick. Anyways, whats on there now has curred but I still want to add a thicker coat but I want to stay away from truoil if i can. Can you spray Nitrocellulose on top of Truoil? Thanks.

redir · #2 05-17-2018, 01:19 PM

My guess is that Tru Oil is softer then Nitro and you don't ever want a harder finish on top of a softer one.
FWIW I have used just about every finish in the book except Tru Oil. I decided to give it a go on a Uke I built a while back and was quite impressed with it. What dont you like about it?

C_Becker · #3 05-17-2018, 01:43 PM

I guess its possible, I've read before that you can shoot nitro over tru-oil.

But what I'd do is buff the tru-oil you got on there with some fine steel wool, so you get a nice and even surface.

After that I'd just add more coats of tru-oil.

Make sure to put it on very thin, but lots of coats. That way you'll get a really nice glossy finish.

arie · #4 05-17-2018, 03:50 PM

just level it and hit it again -sparingly.

fwiw, a "thicker coat" of anything on an acoustic is generally not the pathway to tonal enlightenment.

redir · #5 05-18-2018, 07:13 AM

Quote:

Originally Posted by arie

just level it and hit it again -sparingly.

fwiw, a "thicker coat" of anything on an acoustic is generally not the pathway to tonal enlightenment.

That's what I did too. Build up, level, then top coat. I 'cut' the Tru-oil considerably too and it wiped on nice and thin for the final coats.

Rodger Knox · #6 05-18-2018, 11:10 AM

Heating the TruOil up to about 120°F before wiping it on helps thin it out.

yellowesty · #7 05-18-2018, 11:36 AM

Thinning Tru-Oil with naptha (around 1:1, not critical) slows the drying to allow spreading the finish more easily and thinly. I use thinned Tru-Oil applied with coffee filters and bare hands. It typically takes 7 to 10 coats (no more than 2 coats a day with light sanding after every 3 coats and finishing with 0000 plastic wool) to get a finish I like. I don't pore-fill and get a "mildly glossy" result. The only time I had trouble was with a very oily wood -- and inadequate acetone prep (my bad).

JDaniel · #8 05-18-2018, 12:41 PM

Quote:

Originally Posted by redir

My guess is that Tru Oil is softer then Nitro and you don't ever want a harder finish on top of a softer one.
FWIW I have used just about every finish in the book except Tru Oil. I decided to give it a go on a Uke I built a while back and was quite impressed with it. What dont you like about it?

Maybe I have this upside down, but Behlen recommends vinyl sealer underlaying nitro for the reason that it is flexible; nitro without that flexible base is apparently subject to checking when the wood's moisture content moves. I haven't experienced this, but I'm a rank amateur with lacquer. Tru Oil on the other hand can produce a really nice finish and I believe there is a lot to like with it.

Rodger Knox · #9 05-19-2018, 01:51 PM

Quote:

Originally Posted by JDaniel

Maybe I have this upside down, but Behlen recommends vinyl sealer underlaying nitro for the reason that it is flexible; nitro without that flexible base is apparently subject to checking when the wood's moisture content moves. I haven't experienced this, but I'm a rank amateur with lacquer. Tru Oil on the other hand can produce a really nice finish and I believe there is a lot to like with it.

More flexible doesn't necessarily mean softer, but I'm no expert either, except maybe with TruOil. I've used TruOil extensively.

Peegoo · #10 05-20-2018, 01:13 PM

Nitrocellulose lacquer is actually quite soft.

It will work fine over Tru Oil, which is a wiping varnish--not an oil. Unlike an oil finish, Tru Oil cures and hardens.

Just be sure to completely de-gloss the surface of the Tru Oil with nothing more coarse than 400 paper. It makes getting a level surface easier with no sanding marks showing through the nitro. Also, if you go too fine, like 600, it will be too smooth and there will not be enough "tooth" for the nitro to grip.

A very cool way to apply Tru Oil is to wet-sand with it. It's an old gunsmith's trick to create a self-leveling surface that is glass smooth. Back in the old days they used boiled linseed oil for this purpose.

After leveling the wood with 320 grit, you apply a few drops of the oil to the wood and lightly sand with 400 grit in a small area. The cream that builds up (oil and wood dust) packs the pores in the wood, and you leave it on the wood; don't wipe it off. When the paper starts dragging, add a drop or two more and keep going. It takes a week or so to do right, but the results are pretty amazing. If you've ever seen older rifle and shotgun stocks with finishes that look a foot deep--this is how they did it.