I am working on finishing a rosewood guitar and have many spots where the tru oil is not soaking in / bonding 9whatever it does) to the wood. I have sanded TO off and sanded wood down, but keep getting same results.
https://goo.gl/photos/dPJuZYGE1WicUpVc8
any suggestions?
tru oil not bonding to rosewood
Moderator: Dave Bagwill
Forum rules
The purpose of this forum site is to provide a means for acoustic guitar makers at all skill levels to forward information, share experience and ask questions if project obstacles are encountered. We ask that egos be left at the door – the highest levels of courtesy and respect are to be shown to all. Posts containing disparaging comments will be removed. The “Acoustic Guitar Construction Forum” is owned by Kenneth Michael Guitars and is copy protected. Direct links to luthier suppliers are not permitted and will be edited.
The purpose of this forum site is to provide a means for acoustic guitar makers at all skill levels to forward information, share experience and ask questions if project obstacles are encountered. We ask that egos be left at the door – the highest levels of courtesy and respect are to be shown to all. Posts containing disparaging comments will be removed. The “Acoustic Guitar Construction Forum” is owned by Kenneth Michael Guitars and is copy protected. Direct links to luthier suppliers are not permitted and will be edited.
Re: tru oil not bonding to rosewood
I have tried a few things with this, but had same results. I washed with mineral spirits and DNA. have done a couple thin coats of shellac under TO. have done sanding slurry with TO / mineral spirits. I have sanded to about 1200 grit but originally tried sanding to about 220/320.
I suspect that maybe something is in the wood - glue or other - although I don't recall having spilled anything on it. not sure if this could be because of the oily nature of rosewood - which I have not worked much with before. I did not have similar problems on mahogany instrument previously.
I have not tried acetone to clean it - that was recently suggested. but need to get to the store to see if that makes any difference.
I suspect that maybe something is in the wood - glue or other - although I don't recall having spilled anything on it. not sure if this could be because of the oily nature of rosewood - which I have not worked much with before. I did not have similar problems on mahogany instrument previously.
I have not tried acetone to clean it - that was recently suggested. but need to get to the store to see if that makes any difference.
-
Hans Mattes
- Posts: 105
- Joined: Mon Jul 04, 2016 6:32 pm
- Location: Petaluma, Calif.
Re: tru oil not bonding to rosewood
I had EXACTLY the same problem with a guitar I built last Fall. The picture of your guitar could have been a picture of mine. At least on mine, the issue was only on the back; the sides gave me no problem. I tried a number of remedies, some of which helped, some of which didn't. What finally did work for me was cleaning the surface VERY aggressively with acetone and then sealing immediately with shellac before applying the Tru-Oil.
Like you, I thought I had damaged the wood or gotten glue on it, but no, it was oil leaching out of the rosewood and mixing with the Tru-Oil before it had set up. Depleting the oil with multiple acetone wipes and then sealing the surface before more oil could migrate to the surface seemed to be the trick. The final finish with Tru-Oil came out just fine.
Keep at it.
Like you, I thought I had damaged the wood or gotten glue on it, but no, it was oil leaching out of the rosewood and mixing with the Tru-Oil before it had set up. Depleting the oil with multiple acetone wipes and then sealing the surface before more oil could migrate to the surface seemed to be the trick. The final finish with Tru-Oil came out just fine.
Keep at it.
Re: tru oil not bonding to rosewood
This knowledge is helpful. My sides on mine are fine too.
I picked up some acetone on way into work today. Can you give more details about what you did with it?
My plan at this point is to
- sand off the latest coat of TO
- clean with acetone. you said very aggressively - what does that mean? - wipe down many times? scrub? let sit on wood. I've not used acetone before, so any insights would be helpful - guess I need to do some research too.
- shellac immediately after - does that mean first coat, or very quickly after cleaning with acetone?
- then begin thin TO coats.
I picked up some acetone on way into work today. Can you give more details about what you did with it?
My plan at this point is to
- sand off the latest coat of TO
- clean with acetone. you said very aggressively - what does that mean? - wipe down many times? scrub? let sit on wood. I've not used acetone before, so any insights would be helpful - guess I need to do some research too.
- shellac immediately after - does that mean first coat, or very quickly after cleaning with acetone?
- then begin thin TO coats.
-
Hans Mattes
- Posts: 105
- Joined: Mon Jul 04, 2016 6:32 pm
- Location: Petaluma, Calif.
Re: tru oil not bonding to rosewood
I'm not sure that you need (or want) to "sand off the latest coat of TO." Where the TO has cured without interference from rosewood oils, it should be fine. I'd just lightly sand the back, focussing on the oily areas, and then, using a paper towel that's fairly wet with acetone, wipe on and wipe off repeatedly, turning the towel often to pick up the maximum rosewood oil and avoid spreading it around. When the towel is no longer getting color from the rosewood, it's time for a thin coat of shellac and then the TO.
I thin the TO about 20% with naptha and apply, literally, by hand. I start with a drop on my index finger and rub it in circles, spreading it as far as it will go. I tend to finish the spreading with a full palm moving with the grain and finish with a wipe (with the grain) using a coffee filter. Then I wait at least 6 hours between coats (typically 2 coats a day) and level with grey synthetic steel wool after 4 coats and again after 8 coats. I finish with a rub down using white (0000) synthetic steel wool after another two coats and call it done. The results don't mimic a gloss lacquer/nitro finish, but are shiny and have, to my eye, a less "plastic" look.
I'm NOT qualified to justify this, but I don't use a glove for either the acetone (it's a major ingredient in nail polish remover) or for applying TO. I do find that the residual TO washes off my hands easily using auto shop hand cleaner if I don't wait long before washing.
As an aside, I'm now completing a build using Black Acacia instead of rosewood, and I've had no issues with the TO finish, even though I didn't wipe with acetone and didn't seal with shellac. And it's a very attractive wood. We'll find out soon how it sounds.
I thin the TO about 20% with naptha and apply, literally, by hand. I start with a drop on my index finger and rub it in circles, spreading it as far as it will go. I tend to finish the spreading with a full palm moving with the grain and finish with a wipe (with the grain) using a coffee filter. Then I wait at least 6 hours between coats (typically 2 coats a day) and level with grey synthetic steel wool after 4 coats and again after 8 coats. I finish with a rub down using white (0000) synthetic steel wool after another two coats and call it done. The results don't mimic a gloss lacquer/nitro finish, but are shiny and have, to my eye, a less "plastic" look.
I'm NOT qualified to justify this, but I don't use a glove for either the acetone (it's a major ingredient in nail polish remover) or for applying TO. I do find that the residual TO washes off my hands easily using auto shop hand cleaner if I don't wait long before washing.
As an aside, I'm now completing a build using Black Acacia instead of rosewood, and I've had no issues with the TO finish, even though I didn't wipe with acetone and didn't seal with shellac. And it's a very attractive wood. We'll find out soon how it sounds.