PDA

View Full Version : stripping / refinishing advice needed



strumsilly
09-21-2014, 12:36 PM
I just purchased a 40- '50's ?Favilla baritone. and undisclosed to me this instrument has been badly refinished.lots of runs, dust, and it's thick and soft. I don't know what it is, but I wish they left it alone. There is a stunning one piece mahogany back and top screaming to be released.. I'd like to go to a satiny oil [tru-oil?] finish. advice? I have refinished furniture, but never a ukulele. should I get the belt sander out. just kidding. what is the safest way to get this stuff off. I am thinking of starting with a mild stripper in an inconspicuous spot . I would leave it alone if it wasn't such an amateurish job.

Matt Clara
09-21-2014, 01:26 PM
Is there any binding on the instrument, and if so, does it look plastic? If it looks like plastic, I would strip the uke entirely with sandpaper. If it looks like wood or there is no binding, I would use a chemical stripper on the instrument, and then sand carefully starting at something like 120 grit through 220 or 300. Tru-oil sounds good and simple.

billten
09-21-2014, 02:07 PM
I'd try a very sharp scraper before sandpaper, it often removes finish a lot more cleanly than the grit of sandpaper. Keep it very flat and very sharp though...

strumsilly
09-21-2014, 03:11 PM
Is there any binding on the instrument, and if so, does it look plastic? If it looks like plastic, I would strip the uke entirely with sandpaper. If it looks like wood or there is no binding, I would use a chemical stripper on the instrument, and then sand carefully starting at something like 120 grit through 220 or 300. Tru-oil sounds good and simple.
no binding, solid mahogany.

strumsilly
09-21-2014, 03:12 PM
I'd try a very sharp scraper before sandpaper, it often removes finish a lot more cleanly than the grit of sandpaper. Keep it very flat and very sharp though...
no harm in trying it. but I also need to remove the finish on the neck and bridge, that would be challenging with a scraper.

Matt Clara
09-21-2014, 03:15 PM
I'd try a very sharp scraper before sandpaper, it often removes finish a lot more cleanly than the grit of sandpaper. Keep it very flat and very sharp though...

I'd use a chemical stripper, and then sand smooth. That's what I meant to say, in case I didn't. If the old soft finish is nitro, acetone and lots of clean rags will take it off in a hurry.

strumsilly
09-21-2014, 03:43 PM
I'd use a chemical stripper, and then sand smooth. That's what I meant to say, in case I didn't. If the old soft finish is nitro, acetone and lots of clean rags will take it off in a hurry.
thanks. I might try some solvents , acetone, mineral spirits. maybe I don't need a real powerful stripper. I can almpst crape it off with my fingernail in spots.

Allen
09-21-2014, 04:21 PM
If it's coming off that easily, then one of the quickest ways to strip a finish back is with a single edge razor blade. You use it like a scraper. That is holding it firmly between thumb and forefingers at 90 degrees or there a bouts to the surface. The small size makes it ideal for getting into tighter spots than a conventional card scraper will.

71101

Inksplosive AL
09-21-2014, 05:22 PM
Not rocket science for certain.

~peace~

Chris_H
09-21-2014, 06:59 PM
+1 to what Allen said.. or, the longer 'breakaway' razor knife blades. They make great scraper blades.


And no, not 'rocket science' as Al says..

more like voodoo....



good luck

Beau Hannam Ukuleles
09-22-2014, 04:14 AM
if you have gloves, a mask and acetone, i have used an old towel and splashed acetone and pulled and wiped finish off.

or sand/scrape

Kekani
09-22-2014, 07:10 AM
Scrape.

Actually, what Allen said. I stole the razor blade from him when I saw it used on epoxy. That technique is good stuff. I can't even remember why I bought that big pack of razor blades for in the first place, that was more important than scraping epoxy. . .

strumsilly
09-22-2014, 07:48 AM
here is what it looks like
71113

ericchico
09-22-2014, 08:00 AM
here is what it looks like
71113

I swear I didnt let my 3 year old finish that poor thing. If you were going to use a stripper on that would it be waterbase like Back To Nature or more solvent based like Jasco?

strumsilly
09-22-2014, 10:02 AM
I swear I didnt let my 3 year old finish that poor thing. If you were going to use a stripper on that would it be waterbase like Back To Nature or more solvent based like Jasco?
I don't know yet. I thought if I used stripper, I'd start with the mildest and work from there.

Chris_H
09-22-2014, 10:15 AM
Something you may run into in refinishing this thing... If you sand back down into bare wood, and the bridge is still on, the fretboard still attached, it will be quite difficult to 'cut' evenly through the patina of the old Mahogany, and you will likely forever after see the differences in the wood color where the old patina still kind of exists, and where the fresh wood was exposed. It will mellow somewhat, but likely you will see this for a long time. It is hard to tell exactly what you are up against from that small pic, but, I think that even color in the wood will be the biggest challenge in getting a really nice finish if you strip it completely, or sand / scrape into bare wood. This will be most evident in the places where it is difficult to cut back into fresh wood, like around the bridge, fretboard end, neck body join, etc..

Alternately, maybe you could carefully sand the finish, starting with maybe 320, very carefully on a rubber block, sanding the bubbles and junk out of it. It will require a lot of care to not sand too thin on the corners, and also possible that there is some color in the finish. If you can manage to sand out most of the imperfection in the existing finish, without going into bare wood, and cutting no deeper than necessary (anywhere) that might be the best route to go. For the first coat, a coat of Bullseye Sealcoat, just to ensure good adhesion, and protection from any contaminants which could possibvly have entered the old finish, or deeper. Old contaminants can cause fisheyes in a subsequent re-finish, or poor adhesion. The shellac based Sealcoat is a cure all for that sort of thing.

If it were my project, I would be thinking in terms of minimal invasiveness, of repairing instead of replacing.

Beware of starting with too coarse a grit of abrasive, and use a block on the flats, a soft block on the curves. A block will prevent the abrasive from following the irregular surface you are trying to repair. 320 might be a good place to start. I would definitely not start cutting into that finish with intent to repair it with anything coarser than 220, and I think that is a little too coarse anyway. At 400, a little water with soap added may help, wet sanding style. If you could get that finish to where the color is still consistent, and all the runs/ drips/ irregularities are sanded out, and it is smoothly sanded to at least 320, put a coat of Sealcoat on it, then maybe a couple or three coats of very thin varnish, you could have a nice finish, and that nice color that the instrument already has, at least the part in that pic. If you sand through into bare wood, unevenly, you might make something that looks just as bad as it already does, just different.

To sand out the imperfection to a place where repair might be an option is an advanced project, so take it slow and careful. Whether scraping or sanding, every stroke/ pull/ push, is a 'cut. Watch the color closely. Watch everything often and carefully. It looks like it might be possible to end up with a nice finish.




Just guessing,,, I would probably start with a rubber block, 3m 400 grit, and a bit of water. Careful not to let ANY water get inside, or into raw wood.


And if you use a stripper.... barefoot!! no heels ...

strumsilly
09-22-2014, 10:43 AM
thanks Chris. It wouldn't hurt to go that route, the light sanding. I might be able to live with it if I could get all the runs and bumps out.

Chris_H
09-22-2014, 11:56 AM
Runs are most easily scraped out, if the finish scrapes without chattering or shattering. Sanding out a run without a block will thin the adjacent finish as much as it will take down the run, and getting that last little line around the run will be very difficult without a block. Many people will use a razor blade with tape wrapped around both edges of the cutting blade, with a gap just wide enough to scrape the run down, and the tape giving at least some protection to the surrounding finish.

strumsilly
09-27-2014, 04:49 AM
I'm going the sanding route, and started wet sanding the back with 400 grit, it was taking forever so I went down to 320. It's looking really nice. I went through the finish in one small spot and it lightened up there so I learned to be more careful. I'm not going to be able to get all the imperfections out, but it already is looking and feeling much better.

Timbuck
09-27-2014, 05:09 AM
I'd be tempted to part dismantle the uke before re finishing it....remove bridge and fretboard and neck, then scrape, sand, blowlamp, paint stripper, whatever works best...But thats me ;)

Titchtheclown
09-27-2014, 05:16 AM
Sometimes just a little heat helps the scraping.

strumsilly
09-27-2014, 05:25 AM
I'd be tempted to part dismantle the uke before re finishing it....remove bridge and fretboard and neck, then scrape, sand, blowlamp, paint stripper, whatever works best...But thats me ;)
that would probably be best , but that is beyond my expertise. I did take the strings and tuners off.

Chris_H
09-28-2014, 07:23 PM
If you went through the finish and through the patina in the wood, Pandora's box may be opened already. It might be a good idea to seal up any bare wood now with the sealcoat. If you are going to refinish it, removing the bridge is a good idea.

Careful sanding...

Good luck

strumsilly
09-29-2014, 05:02 AM
the sanding went really well. it's not perfect, but it is vintage. After the 600 grit I went to buffing with meguires polishing it looks 100% better. I'm going to stop and put some strings on it for now. will post some pics when I get er done.

Chris_H
09-29-2014, 05:41 AM
Waxes like Meguires often introduce things that soak deep into the finish, and even into the wood, which, when someone in the future goes to refinish the instrument again can cause problems like fisheyes.

I use waxes on automotive finishes, but never on nitrocellulose lacquer. Maybe someone knows of waxes that are safe over nitro? I do not, but I have not researched it. Personally, I recommend keeping those waxes far away from lacquers and varnishes, and instrument finishes in general. If anyone out there knows different, please correct me.

Looking at the photo posted by the OP, I would have taken the route of repairing the finish, very carefully, mostly taking care to leave the original patina of the finish and the wood intact, but smoothing the finish. Then I would have applied a couple of thin coats of something. After the Meguiar's has gone on, applying coats of finish is tempting fate.

strumsilly
09-29-2014, 06:05 AM
I used Meguiar's ultimate compound, which is a rubbing compound. I smoothed the finish by sanding , then buffed. I don't plan on doing anything else for now. It does recommend waxing after the compound, but I'll follow your advice and not wax it.

strumsilly
09-29-2014, 06:21 AM
pics...........................
713727137371374

RichM
09-29-2014, 06:32 AM
Can't speak to the technical aspects, but as far as aesthetics go, that thing looks a million percent better than it did.

Chris_H
09-29-2014, 06:46 AM
Yes, Meguairs is designed for automotive finishes on metal. Stay away from waxes on wood finishes, unless you are doing a shellac and wax finish.

I did not see your sand through in the pics. How did that look? Can you get a pic that shows the texture of the rubbed finish? Curious to see. Were you able to completely remove the sags and bubble marks?


It is difficult to see in the pics, but if you managed to remove/ reduce the previously existing flaws in the finish, and at the same time, leaving minimal trace of your work, great job! And you did not even have to pull out any finishes, nor from what I can see, mess with the existing gorgeous patina of the Mahogany. :)

strumsilly
09-29-2014, 07:09 AM
thanks for all of your advice Chris. I was not able to remove all the sags and bumps, but compared to how it looked and felt, it's lots better. One of my main goals was not to mess up the beautiful color the mahog has , very similar to a gibson baritone I once had [another member now has]I'll try to take a picture of the texture, but it is hard, you have to get just the right angle without glare. I need to go back and buff some more, but hand buffing is time consuming and I was anxious to get er playing.