View Full Version : Wood Fill?

Feb-01-2004, 2:05am
Inevitably, on my first mandolin, there are a couple of small spots that need slight fill in the wood. I plan to use stain and I don't want a spot that won't accept the stain. I also don't really want to use wood filler if I can find a better way.

My question is: should I go ahead and stain the body and neck, defects and all and then do some drop fill on top of the dents, sanding out later? Or is there some incredible formula for mixing wood dust with some ingredient that will take stain--sanding it out and staining afterwards?

I've used sawdust and super glue for fingerboard repairs, which worked fine, but I don't think that is going to work for wood that needs to take stain. If worse comes to worse, I have wood fillers, but what I am wondering is if there is a do-it-yourself type of match up technique using fibers of similar wood.

By the way, thatnks to everyone's help, #1 is coming along pretty well. I am thankful and grateful for the multitude of great suggestions. I'd be lost without you all!

Michael Lewis
Feb-01-2004, 2:52am
Crawdad, if you have dents (compressed wood fibers) you can remove them with a soldering pencil and a wet paper towel. Wet the dent, place the dripping wet paper towel (folded several times)on the dent, and immediately apply the tip of the soldering pencil to the dent area for a few seconds. Don't let it burn, keep it wet. You will be amazed at what you can restore. This doesn't work for chips and missing splinters. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/coffee.gif

Feb-01-2004, 2:57am
Michael--Thanks for that. Unfortunately, these were caused by man made slips. (sopmebody must have snuck into the shop while I was pretending to be a master luthier,!) I have to replace the #(now) missing wood. What can I do to remedy that?

Feb-01-2004, 9:34am
Crawdad, If you're talking about big missing pieces of wood, you can replace them with carefully fit pieces of matching wood.
If you're talking about those little spots that just wont fill in the finish, you can learn to fill them with stick shallac and a burn-in knife. If you're not at all familiar with this, there's more to it than I can go into in a post here, but I can refer you to where to read about it and I'll be glad to answere questions and help you if I can.

Jim Hilburn
Feb-01-2004, 9:55am
I got a tube of the wood filler Stew Mac sells years ago. I've long since taken it out of the tube and it's in a plastic bowl and its like a big ,hard rock. At finish time for each instrument ,I break off a little chunk and re-liquify it for any fills I might need. Thankfully ,there are less and less to do as I get better at this.
When I use it ,I get it very wet and force it into the gap as best I can. There's a limit with how deep and wide a gap you can get this in. Nugget always said to use matching wood if possible ,but it has to be fit very nicely ,or you will see the seam ,and in some cases ,filler may be the best choice. Trying to made tiny slivers if wood with the right grain orientaion and color match isn't easy. Thankfully ,sunburst's can hide a lot of problems.
I'm still looking for a filler just to do the binding -wood junctions.What seems like a near perfect fit will turn into the Grand Canyon after the first finish coats but filler won't go in there. I've been drop-filling them with lacquer ,but that's risky when you try to blend and level it. I learned the hard way that superglue is the wrong thing for this. I'm open to suggestions. I've thought about doing paste filler like you would use as a grain filler.

Feb-01-2004, 11:05am
Jim Hilburn,
After looking at the pictures of your mandolins I don't really feel qualified to offer suggestions on binding work. Looks to me like whatever you're doing is working just fine!
But anyway, here are some things that work for me after putting the binding on and before sanding:
If I can actually see a gap between the binding and the wood, I can heat the binding with a heat gun 'til it softens enough to press the gap tight with my fingers. Just hold it 'til it cools.
Any place that I don't see plenty of glue squeezout and I suspect I might get one of those "grand canyon"s, I drool some Duco cement on the area and let it dry. It will disolve the binding somewhat and soak into the gap taking some dissolved binding with it.
If I have a place that needs a minor repair, I use my "ivoroid mud". That's ivoroid binding dissolved in acetone to the consistency of putty.
If the binding you're using is not celluloid plastic, the duco wont help much. You would have to use a heavier bodied glue more compatible with the ABS or bolteron or whatever it is. It wont disolve the binding but it'll help fill the gaps.
Hope some of this helps.

Chris Baird
Feb-01-2004, 11:36pm
I find most of my annoying little binding gaps come from the binding not the channell. I always make sure my binding is dead flat on the bottom edge. If I do get a micro gap I just fill it with ivoroid melted in acetone. This makes the gap invisible because as I said its usually not the channel its the binding. I build blonde instruments so getting perfect bindings has been a real challenging priority.

Feb-02-2004, 4:12am
Good tips for the binding. I'm gonna have to make myself a jar of that liquid dissolved "mud", Sunburst.

I was hoping there was some substance I could add wood dust to in order to get color accurate fills. Is there such a thing?

Chris Baird
Feb-03-2004, 12:19am
I bought a selection of wood fillers of different colors. get the kind made with real wood. Mix and match them then let dry and figure out which matches best. They will take stain.

Feb-03-2004, 12:08pm
Chris--I think the mix and match is definitely a good idea. I have several shades of brown fill which should get me pretty darn close to what I need. I still wish somebody would make a clear wood fill base which I could add sawdust to--that would be so cool!

For things like ebony or rosewood fingerboards, I have used super glue and sawdust to do some pretty perfect little fill repairs. Unfortunately, that doesn't work for any wood surface that I would want to stain.

What about these melt in shellac sticks? I imagine those are more for touch up repairs since they probably don't accept stain either.