MIMF

I used tung oil when building some mountain dulcimers years ago and found it lent itself well to a kitchen table workshop, but took a long time to cure. I learned that it is actually a wiping varnish that contains tung oil. It cures by oxydation and not by evaporation. For this reason care must be taken with used rags or cloths after application. Oxydation releases heat. If the used rags are not well ventilated they can easily catch fire spontaneously. I would simply toss them in a can and leave them outdoors.

I don't know how tru oil dries, but the mfr. recommends that when using it with oil bearing woods like cocobolo or rosewood, it should be thinned slightly with mineral spirits. Tru-oil has been the go-to finish for gunstocks for many years; apparently the U.S. military switched to it from linseed oil in 1941 because linseed treated rifle stocks would begin to smoke under sustained firing and the finish would get sticky. Or so the story goes. I'd like to try it for a guitar neck.

Here's an interesting article about oil finishes. http://www.popularwoodworking.com/techn ... ry-and-use

I am a fan of shellac for the neck. I pad it on until I like the feel, then stop. Super easy and has a very smooth feel.

How well does the OSMO polyx oil fill pores as in mahogany?

Also, has anyone used dye prior to applying OSMO?

I have only used PolyX on maple.
I don't think it would fill pores in mahogany with out a lot of coats. It goes on quite thin.
I only used it on natural wood with no dye or stain.

Stephen, OSMO makes a range of stains and wood fillers that you might check into. I bought a Birchwood Casey Walnut gunstock refinishing kit years back when that was the only way to get Tru-Oil. The walnut colored paste filler might be just fine for darker mahogany if it's still available.

on the last guitar I finished I used a product called Paraloid B72. It's typically used in art conservation, but depending on the solvent dilution it can be used as a stabilizer for punky wood, a fixative, or a very thin finish. It comes in pellet form and it's basically a polymer acrylic, and can be dissolved with Acetone, toluene and isopropanol. I added some tru oil to a 30% cut of acetone and pellets, to get more of a varnish characteristic, since acetone flashes so quickly. It doesn't build the same way a varnish will, as secondary coatings can dissolve the initial application, though I think if you sprayed it you could get past this.

I basically applied two coats on a maple laminated neck, (had walnut stripes), with a rag and used 0000 steel wool in between the coats. As I said its kind of a pain adding second coats, so there were a couple spots where I had some pulling and had to focus on these with a few quick passes of 320 grit, before I moved back to steel wool and then onto some micromesh pads.

Long story short, it's the slickest finish I've ever felt on a neck, even more so than finely sanded shellac. The wood looks like it doesn't have finish on it at all, but it doesn't take any dirt or oil off of your hands. It's been on there for a couple years now and hasn't had any issues.

I originally stumbled across this in a really obscure Bonsai forum that besides this had very little useful information! Someone was using this to preserve deadwood on their bonsai trees which are typically kept outdoors. I figured if it would work for that, I could come up with a way to use it on a guitar. Here's a link to the stuff I'm talking about if anyone wants to experiment with making their own.

http://www.conservationresources.com/Ma ... n40_04.htm

I've used Formby's low gloss tung oil for four guitars, and I don't understand the concern about it not drying completely. Of course, I don't use it as it's typically applied. I give all surfaces a wash coat of 1lb cut shellac, hit it with 0000 steel wool, then wipe on several coats with a folded square of t-shirt. I'll do swirls across large surfaces, then long swipes, in a sort of quick French polish imitation. Bodies get 7 or more applications, maybe 5-6 on the neck and fingerboard, with as little as an hour between coats. It can get quite smooth and glossy, buffed with a dry piece of t-shirt, and I've also knocked it back down with the steel wool for a matte finish. I'm going to try the EnduroVar for the next batch I have on deck, but might keep doing the oil on the neck.

[quote="Jason Rodgers" "and I don't understand the concern about it not drying completely"

Jason, so do they dry out eventually? And do they stay dry?

I think the concern about Tung Oil not drying refers to pure Tung Oil. Formby's is a oil varnish blend. Minwax Tung Oil Finish, Tru Oil and Waterlox are all similar and all very good finishes for a natural look and feel. I find it best to just pick one and stick with it. I like Minwax because I can always find it at Home Depot. I've mixed my own, with Varnish and BLO and mineral spirits, but it's really no better or less expensive than these commercial products.
My procedure with the Minwax is sand to 220 and apply the first coat and work around the whole body twice. Wipe off everything that will come off. Wet sand with 400 and boiled linseed oil. I feel like if the is any residue it will mix with the Minwax. For Mahogany, I add some rottenstone to help fill the pores. Second coat, Wet sand with 600, third coat and it's done.

John,
We had a discussion on the old forum about B72 that goes back probably 10 years now. I guess it's virtue is that is doesn't polymerize further as it dries so that it can always be reversed and removed later with more acetone. It's not unlike shellac in that respect.

All "drying oils" will dry eventually on their own but we typically speed that up by altering the oil to help it form molecular chains and become a polymer solid. With linseed oil, we boil it and add Japan drier https://en.wikipedia.org/wiki/Oil_drying_agent which mostly contain cobalt salts. Some violin varnishes need UV light to help activate the cross linking and speed up the drying. Heat is another good way to dry oils, it's why we oil and bake cast iron pans to season them. Pure tung oil is quite resistant to polymerization which is why it gets a bad rap for staying sticky for months and years and continuing to ooze out of wood pores decades after it was applied.
There's a good rundown of common drying oils here: http://www.woodworkersinstitute.com/page.asp?p=567

And, watch out for the oil-based finishes over Rosewood. A finish that might dry overnight on spruce may stay soft for quite a while on Rosewood. Sometimes a shellac base coat solves this problem.

Stephen Neal Saqui wrote:[quote="Jason Rodgers" "and I don't understand the concern about it not drying completely"

Jason, so do they dry out eventually? And do they stay dry?

Yes, and I guess because of what Weir said. Additives and such.

I have always used DemBart Checkering and Gunstock Oil. Thinner than TruOil and does "soak in" more and dries hard.

With mahogany or walnut a fair amount in an initial coat or two and let it dry. I then wet sand 400, 600 and even sometimes 800 using the oil to create a grain filling slurry, massage it in, let it dry hard then wet sand and wipe as many times as it take for filling. 000 steel wool and then a few or more coats of light hand rubbed [skin friction is your friend].

Maple, dry prepped to 600 doesn't require much wet sanding [no open grain] but basically the same procedure.

Can be renewed or touched up easily at any time.

Bit of DemBart's wax doesn't hurt the end product at all.

Mike

I have now used the Osmo PolyX Oil Satin Finish, for 2 necks. One, the repair I did on my friends bass, and the second, a new build that I am just completing.
I really like this stuff. It is easy to apply; wipe or brush on, and wipe off, laving a thin coat.
It dries quickly and hard, leaving the wood feeling like wood, with no oily residue. The wood will not stain from sweating hands either. I used it on the maple fret board too.
I have even used it on a cherry fret board, and so far everything looks good.

Soap is wonderful - it gives that 'just scrubbed' silky feel to wood. Given how often I get a guitar in that looks as though it's never seen a wipe down, an added benefit is the ability to just hose the guitar down and wipe away all that dirt and oily crud.

And yes - a soap finish is a real thing, and is does have a delightful texture. Organic (in the sense of being free of VOCs and other dangerous chemicals...which are of course themselves 100% organic in the chemical sense...go figure), inexpensive, and easily renewed. For those seeking NO sheen, minimal protection, and the ability to get as close to bare wood as possible, it's a winner-winner-chicken dinner.

https://blog.lostartpress.com/2015/09/1 ... -warnings/

That is crazy-interesting. Finish from milk, eggs, salad dressing, now soap! What's next? pate primer?

Chuck Tweedy wrote:That is crazy-interesting. Finish from milk, eggs, salad dressing, now soap! What's next? pate primer?

Psh, the foie gras would be grain filler, not a primer.

Yea, I was going for alliteration, but you fixed that - thanks

Enough with the pureed meat, this soap finish is neat. https://www.canadianwoodworking.com/tip ... oap-flakes

But don't all the bubbles just add to your troubles?