I don't use Tru-oil, but it's probably not going to react much differently from any other finish in this sort of application.

I don't know of many glues that bond very well to finishes of any kind except CA, and I would probably avoid using that here. But as long as the inlays are well bonded in their cavities, I wouldn't worry too much about the bonding strength of your filler-- there is not going to be any mechanical action trying to force the filler to fall out.

It might have been better to apply your filler before refinishing the surface, but c'est la vie. Would I suggest you strip it down again? No. As long as you get your mixture right, the filler will probably stay in there.  If you add a little alcohol dye to your glue, you won't need too much ebony dust.   But it would be advisable to seal over the whole thing with another coat or two of finish, to keep humidity and moisture from degrading the filler.

You probably could have cleaned up the Tru-oil surface with 000 steel foil. I think the brush strokes you were referring to were just residue left on the surface.

I don't apply Tru Oil with a brush, but I do get rough surfaces sometimes and have to smooth them before proceeding with finishing. My best method so far is to use worn out 220 grit sandpaper after the second coat, or in your case I would have used that to remove the streaks. Then I do two more coats and use 400 grit sandpaper, and then a last very light coat. I've tried rags and paper towels and my best material for application so far has been Scott Shop Towels, which are expensive but I've been using the first roll for about 6 years and 250 to 300 instruments and it's not all gone yet. I cut each towel into 12 roughly 3x3 pieces and use one for each coat.

I use thick CA mixed with sanding dust for inlay filler. It works well except with rosewood, which seems to consistently kick off almost as soon as it's mixed. Can you use a sharp pointed tool to rough up the surfaces of the inlay cavities before filling them in, and knock off some of the Tru Oil from down in there? That way you could maybe get somewhat better adhesion without having to refinish the whole surface. If you do have to refinish I would sand instead of using acetone.

The finish is already in place, so any "I would have.." suggestions are kind of useless unless the O.P. plans a complete do-over.

I believe Bob Chuckrow's advice, or any other "after-the-fact" procedure is more appropriate. Although I've not used Tru-Oil, I also agree that, handled properly, there should be no real issues with the filler. The only problems I would consider would be a waxy finish, a finish which isn't dry, or a solvent based adhesive that might be diluted by the oil. I don't believe hide glue and ebony dust is very reactive.

If the fill falls out (it happens sometimes with fillers of any sort) it can always be redone.

What strength Acetone? I learned the hard way that Acetone can empty a good fingerboard and bleach at the same time.

I got great luck with 70% or higher Isopropyl Alcohol before COVID made it harder to obtain. I recently obtained 90% at a local grocery store in KANSAS. Beauty Supply/on line are more modern sources.

My new friend is "TIMBERMATE" from Austrailia and at Woodworker's Source. I have the Ebony and the Blond which tints very well.
See what that might do for your patience factor. I sympathize.

Are you going to apply more TruOil on the peghead after the new filler dries? That's what I would do, so that the inlay and everything associated with it is under the finish. Several coats -- because TruOil is very thin. I think that would look best and also help to hold the filler in.

I should go ahead and mention that Timbermate disappears nicely under Tru and Boiled Linseed oil.

Thanks all for your replies and ideas! I really appreciate it. I took a look again under varying angles of light this morning at the headstock and saw streaks left by the applicator pads which are intended for applying finishes. I don't want to keep reworking the headstock, but I knocked it all back down with sandpaper. So I was able to remove the finish from around the inlays with acetone after all.

Zachary, I would use a sharp pointed tool to rough up the surfaces of the inlay cavities but am concerned that I would chip the inlay by doing that. Does it make any sense to thin the Tru-Oil so it will level out more and then just apply twice the number of coats? And, I have heard that paper coffee filters also work well and might try that as I have them on hand. But, I just now picked up some of the blue Scotts Shop towels and will try those as well. The applicator pads just aren't fine enough to apply a smooth finish.

martyjoe, it was the luthier who used a brush on the headstock to apply the Tru-Oil initially. And, it does look like they were brush strokes and he admitted that he wasn't able to knock them down. I can only assume that this is the approach he uses on his own instruments since he exclusively uses Tru-Oil and they look beautiful. But it sure didn't work out for this headstock!

G. Edward Porgie, well the finish isn't in place anymore! So it is a complete re-do. I can then rethink my approach.

Helix, it was the strong stuff from Home Depot but it didn't seem to affect the ebony color and I was able to get a brilliant color back with the Tru-Oil. I did look at my wife's fingernail polish remover as a possibility but it had all kinds of additives. I did wipe it all down afterwards with EverClear (95% ethanol) which I have on hand for French Polishing. And, I happened to find some Ebony Timbermate on my cluttered shelf. I must have purchased it for some other project eons ago. So, it makes sense to try using that.

Old Hickory, yes, I will be applying more TruOil after putting the new filler in place. I will be using the Ebony Timbermate. And, will add several layers to make sure the filler stays in place.

Helix, thanks for letting me know that the Ebony Timbermate will disappear nicely under the TruOil. It looks like it dries to a slightly grayish black color.

I’ve used Tru-oil quite a bit, including over inlayed headstocks. I’ve never had a problem with it sticking to epoxy. I don’t think I’d use hide glue on top of a finish. I think I’d take a needle and scratch the oil finish out of the cavity to be filled. Then I’d use a toothpick to fill the cavities with tinted epoxy. Epoxy with a short setting time will shrink more than long setting types, so don't use five minute epoxy gel, and expect to get done in one afternoon. When the filler has cured, level it with a razor blade. Sand the whole surface lightly, then put another couple of coats of finish. Then sand it all level, put on a couple more smooth coats and you’re done. I apply Tru-Oil with a thick, smooth paper towel like a Viva, or those shop paper towels from a paint store. Wipe it on, then wipe most of it back off.

Yes, Truoil can be thinned. I have found it helps in the last couple of coats where you want streaks and strokes to level out. Build coats are used full strength.

I went ahead and cleaned out the inlay cavities with acetone after taking down the Tru-Oil finish back to bare wood. And then worked in Ebony colored Timbermate and knocked it down with a paper towel. I then let it dry and then sanded it down to the level of the inlay. That's where I'm at right now. I'm debating right now whether to start with diluted Tru-Oil or full strength. If I can get smooth coats on without streaks and strokes with full strength Tru-Oil I would prefer to do that and then apply a couple of final coats with thinned Tru-Oil as lightgauge suggests. However it seems like thinned Tru-Oil will more easily self level but will obviously require at least twice the number of coats. I will use the blue Scotts Shop towels as Zachary suggests.

I would use it without thinning. Strokes are not an issue with the build coats. You can steel wool between coats if you want. Build up is slow enough at full strength.

I just put on the first coat without thinning and it looks good!

TruOil is so thin to begin with, I wouldn't thin it. 

My recollection of my one time using TruOil 10 years ago on a mahogany neck and resonator is that I sanded with #320 every third coat. But at one point late in the process, I sanded aggressively (probably removing coats) to reduce yellowing and to go after a drip that had developed and that I missed. I did about 30 coats.

My process was Zinsser's SealCoat (dewaxed shellac), pore-fill with black-dyed drywall compound (SealCoat prevented wood from absorbing color), sand off the filler, then lots of coats of TruOil. I don't remember if I sealed the filler under another thin coat of SealCoat before going to TruOil. I think not.  Allowing TruOil to dry 3 hours or more between coats, I'd usually do three a day. Sometimes four.

Old Hickory, your photos really speak to the beauty of a Tru-Oil finish and the work you put into it! Beautiful! I am going with the Tru-Oil straight out of the bottle without thinning.

Thank you so much.

Up close in person, you really can't tell what it is. TruOil has solids in it, so it does build a film even from the first thin coat. It's a wiping varnish in that respect.  Plus it can be buffed to a shine. Maybe not the highest gloss, but to a luster that lets you know it's there.

quote:

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Originally posted by Old Hickory

Thank you so much.

Up close in person, you really can't tell what it is. TruOil has solids in it, so it does build a film even from the first thin coat. It's a wiping varnish in that respect.  Plus it can be buffed to a shine. Maybe not the highest gloss, but to a luster that lets you know it's there.

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Agreed! It comes out very nicely on bamboo with very little penetration below the surface. 

Way to go, Bill, Timbermate does dry to a gray and then it just makes it seamless Ebony. Glad you had some.

Hi All, I really appreciate all the help you have offered. It really helped get to my goal of getting a smooth Tru-Oil finish on the headstock. And the spaces around the inlays are filled and look great. I have ten coats of Tru-Oil on and will let them cure for at least two weeks. I will then apply a wax finish. The banjo is a Chuck Lee Marble Falls with an 11" pot. When I bought it used there was a finish defect about the size of a half dollar coin near the low D tuning peg string post. It looks like someone had spilled solvent or something that removed some of the finish.

Here's what the headstock looks like now:

banjohangout.org/forum/attachm...ID=296900

Thanks all!

I used Tru-Oil on the one banjo I've built (1979). I just dipped my finger in it and spread it on the wood. It dried smooth and tough without any sign of application strokes. It has been impervious to any kind of wear and small dings. It did yellow just a bit over the abalone inlays on the head stock and heel after a number of years but I'm not gonna worry about that at this point.
From your pictures, your banjo turned out beautifully.

Way to go, Bill, thanks for showing us.

Jim, Yes, using a finger to spread the Tru-Oil is mentioned on the label and it would certainly be a great way to get it rubbed in with no sign of any brush strokes or other application strokes. The Tru-Oil is a great finish as you say and easy to repair if needed. And, thanks for the kudos!

And, Helix, yes, after everyone offering their help I thought I should post a photo of it. I am still letting the finish cure before applying the wax that Chuck Lee uses on his banjos as the final finish. I'm giving it a total of four weeks to cure. I'm anxious to get it back in playing condition again!