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I'm just about at my wits end with the guitar I'm working on right now. It has to do with the finish I'm trying to put on it. I think I understand now what I did wrong, but I didn't when I took a leap into the unknown in a moment of desperation.

Let me back up and explain, so you know what's going on.

I've french polished all the guitars I've built so far, which is the expansive number of eight. I learned sort of a short-cut way of doing it from Brian Burns, but then I'm sure I've added a few short cuts of my own that Brian may or may not approve of. Basically, I was using a 1lb cut of superblonde shellac, and would apply mineral spirits onto the finish just about every other application. This sort of served to level the finish. Whatever. It ended up going on very quickly, and drying very fast between applications. And best of all, I was able to sand it down with micro mesh, progressing from 1500 to 6000 after just a few hours of applications. Then I would polish the surface with the little bottle of white liquid polishing paste that comes with the Micromesh kit. Worked pretty well, really, but I wasn't getting the deep shine, and the finish was quite thin.

So, I decided to try the Milburn's technique. I dunno, maybe I missed a page or something from their website when I was printing out their tutorial, but I was able to get the deep shine, for the most part, but inevitably I'd have a few cloudy spots that would crop up here and there. Reapply and wait a couple hours, and try polishing it out again, and still cloudiness, albeit usually in not exactly the same place.

Frustrated beyond belief -- I mean I've been FP'ing this guitar on and off for two weeks now -- I decided to sand down the back -- just enough to level the finish, I didn't sand through the shellac. And I grabbed a bottle of Formby's Tung Oil Finish, and wiped it on with a clean cloth. Man did it ever look great! Sets up pretty fast, too. I tried to ignore the statement on the back of the bottle that states that it is not recommended for applications over any finish other than a penetrating oil type of finish.

So, now it's been on for a few hours. Still a little tacky. But still looking good.

Only after this did I call a friend of mine who's been building guitars and custom furniture longer than I've been alive, and as soon as I told him about the technique I'm using now, he asked me how long I was waiting before polishing out the shellac. I told him a few hours. He replied that I shouldn't touch it for a week. A week! Turns out, I guess, the reason why I was able to get away with buffing it out so soon before was because the total shellac depth was very thin.

So, anyway, I'm waiting til tomorrow to decide whether or not I should sand off the tung oil finish -- it was only applied to the back, so it'll be easy enough to take off. But I can't help but wonder if maybe I should just leave it on, and apply it to the sides and the neck as well. If I do this, what sort of trouble can I look forward to down the road with a tung oil finish over shellac?

Tell you what, next guitar's gonna be KTM-9. I'm tired of this.

Best,

Michael

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Live to Play, Play to Live

I've had tung oil need a full two+ weeks to harden here in Atlanta in the summer. Humidity slows it down a lot.

I just gave up on KTM-9 and went back to french polish. I won't try it again until I get a spray gun. I don't think a french polish finish will every look like either nitro or the other high-gloss water based finishes. Though I saw a Serge DeJonge guitar once that was almost flawless and had that same "sheet of glass" look but still had the warmth of french polish.

As for the tongue oil, I think that it is probably just sitting on the surface of the shellac and staying wet which is why it looks so shiney. It may never dry. I'd rub it down with naptha to remove the oil and see what it looks like. If it is dull but smooth, I'd just buff it up after giving it a week to dry.

Michael,

The cloudiness you were seeing in the FP was probably due to the mineral spirits. You could be introducing a small amount of humidity into the finish which becomes trapped and then goes cloudy in the final product.
About tung oil... there is a wide variety of formulas available on the market that differ greatly in dry time and working properties so it is difficult to comment on the brand you used. In general I would not put tung oil over a FP or any other finish for that matter. The more coats you apply however, the more build you are going to get and you shoud consider rubbing it out with steel wool and possible a coat of paste wax.     

Hi Robbie,

With this guitar, I have used no mineral spirits. Just shellac at about a 1.5 lb cut and the occasional light drop of olive oil, as per the Milburn's tutorial.

An interesting thing I am now noticing. The area where it was cloudy is now showing through the tung oil finish. Perhaps "dull" would be a better description than "cloudy." "Cloudy" suggests a milkiness, and there isn't any. It's just duller in a few spots.

Prior to applying the tung oil, I sanded the back down. None of the dull areas were noticeable after sanding. So this is something coming up out of the fp. Probably still a bit "wet" right there.

Best,

Michael

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Live to Play, Play to Live

It is hard to say Michael without actually looking at it. It could be also that you didn't get enough coverage in that area when doingthe FP. Maybe you "pulled" the shellac off of that area with the pad when applying.    

Maybe, but I kinda doubt it. I reapplied shellac to that area a couple of more times in the hopes of building it up. Let it sit for an hour or so, then sanded the back down.    Then maybe an hour or so after that, I wiped on the tung oil finish.

Best,

Michael

_________________
Live to Play, Play to Live

Hi Michael

I don't know if it is any help, but a few months ago I was in a hurry to finish a guitar and polished it too soon, On the top the french polished finish looked patchy and dull. I can't be surer but it was almost as if the polishing compound had contaminated the varnish. I know leave them for a minimum of a week before I polish them. In the end I stripped it back and refinished it.

You mentioned at the start you had polished it.