Need advice on repair of tung oil finish (Carvin koa)

Oil is the easiest finish to repair. As you've mentioned you need to clean it first which will make the spot larger. The fix will likely be visible still, just less obvious. Also it will get dirty again with just tung oil.

You can fix it with skill. If you can get your hand on some mahogany or mahogany substitute you can practice on wood that will react very similar to koa.

 

I have a Rickenbacker 650S, it has a walnut/maple body finished in tung oil. Where the previous owner left it in the case with the strap still attached it has a dark stripe across the body. I would be interested to know how I should treat it. A light sanding took the stripe off the maple, but has not touched it on the walnut;



Sorry, not the most helpful of photos.

 

Wax should give some protection from getting dirtier, it may also darken the dirt already there. Oil finishes are fragile and I just accept wear like this.

 

I would imagine that wax may interfere with you subsequently using tung oil if you don’t like the results of the wax.

 

Try using some Murphy's Oil Soap to get rid of the dirt. Rub with the grain. You might find that the finish is in better shape underneath. I have an oiled Koa Carvin and I eventually wanted a glossier finish so I put on a couple of coats of Tru-Oil gunstock finish. It has held up very well. I also used it on the fretless ebony fingerboard. Gives it the look of a polyester coating without the expense. The fingerboard coating actually improved the fretless "buzz" that we all like and has shown very little string wear.

Rick B.

 

+1 on Murphy's as I've never seen it hurt wood or finishes
Send it to a pro to touch up as it is easy to screw up and the pro (either luther or furniture guy)
will probably not be that expensive.

 

I had a koa carvin in the early nineties. Great bass but the Koa was soft and it definitely degraded under the strings where my fingers kept wearing on it. I guess it's just the nature of Koa wood.

 

I'd go with the Tru-Oil on this one. Once cured, finish it off with some BriWax or similar.

I've also gone as far as to apply a faux scratchplate on the vulnerable area. StewMac sells Mylar sheets just for this purpose.

Riis

 

for me, it's a bit like having a dinged car fender repainted. you will always see it afterwards. if it were me, i would leave it as 'character'. alternatively, strip the entire instrument and have it oiled once again. but...it won't last if you play it out.

 

also..it would be nice to see a pic of the entire bass. carvin koa represent!

 

I do alot of woodworking including with open-grained wood like koa and mahogany. I agree with others that a cleaning should be the start (denatured alcohol, then murphys diluted with warm water). Dry it well and make sure to let it sit for a day or two to dry before doing anything else. If it were mine, I'd apply more tung oil once it was clean. But you need to read labels carefully - lots of stuff is labelled tung oil finish, which contains other materials such as varnish. You want to use 100% tung oil. Easy to use - wipe it on, let it soak in for a bit (keep the surface moist with oil), buff it dry with a clean cloth and let it dry.

If you are going to apply oil, then its ok to give it a light sanding first to remove any marks. I'd use 400 grit followed by 600 grit wet/dry sandpaper, very lightly to avoid taking off anything but the very surface. Make sure to wipe off all of the dust - alcohol on a clean cloth should do the trick.

 

I use Tru-Oil for any number of reasons. Here's a link which will help choose the right product for the job:

Tung Oil - Woodwork Details

 

Do not dry sand. Use wet/dry sandpaper (fine) WITH some tung oil. Let dry and apply more tung oil (wiping off excess) as needed. Easy peasy.

 

Not a bad idea, since you will have sticker shock buying pure Tung oil for such a small repair.