Oil finish and spalted maple...

[bassgasser]

Ok i'm building a bass that has a spalted maple top and a swamp ash core.. i want to oil finish it but i know the maple can be soft, is there something i can use on the top before the oil to harden it? Or, should it be ok if i just oil it all with a lot of coats. Also, i know i have to grain fill the ash but what about the maple? isn't it non-porus enough to not need it? thanks

 

[SkuttleFunk]

regular Maple is OK for an oil finish, but spalted Maple is a different story. spalting can range from simple discoloration of solid wood all the way to a complete breakdown of the wood structure (i.e. rotted) that resembles a graham cracker (or worse!) dry bread.

in the case where the wood is simply discolored, you could possibly use oil to finish it - but you'll always have a soft spot where the finish surface is different than the surrounding areas. in the case there the wood structure is soft, spongy, or worse you will need to finish with something that will provide structure to the wood as well as a shiny surface that looks nice. in this latter case, the thin layer of oil that is built up with an oil finish will not provide the structure you'll need to properly finish the spalted areas.

all the best,

R

 

[-CB-]

I'd be real nix on using oil on spalted maple, since also it would make correction of a problem hard if it doesn't turn out well.

There are commercial "rotten wood" strengtheners... those might be of some use, but it would be nice to test on an area that wont show.

For a home finish, I'd be inclined to get a boatload of water thin CA adhesive and use that to fill and strengthen the wood.   You'd do that after staining/toning if wanted the base wood to have a color (ie the middle of a tobacco burst). 

StewMac sells a "clear" grain filler that does an "ok" job too, but I've not used it on deep really porous wood like spalt maple can be.  I mean, I've seen spalt that is pretty much like coarse cork board.  Whaddaya gonna do with that?   It needs epoxy or CA flowed into it.  Not beyond the home finisher, but neither is it just a wipe and play finish.

There are commercial finishes you can get at places that specialize in marine wood.   I've got a place local to me called "Glue Products" that sells all the marine, furniture and custom auto finish materials and supplies.  You might seek out such a place and get something similar to the epoxy they use to coat bar tops with (just use it thin of course). 

For certain, spalt is a challenging thing to get a finish on.

 

[der-watz]

Hi!

I know, a couple of guys use epoxy glue to stabilize spalted woods on guitars. You apply it with a scraper. when it has hardened, sand back and level the surface again. Next, apply a washcoat of shellac (sticks on almost everything). On top of the shellac, you can continue with oil!

Cheers,

Ole

 

[ibob74]

Hi!

I know, a couple of guys use epoxy glue to stabilize spalted woods on guitars. You apply it with a scraper. when it has hardened, sand back and level the surface again. Next, apply a washcoat of shellac (sticks on almost everything). On top of the shellac, you can continue with oil!

Cheers,

Ole

Would the oil adhere to the shellac?

 

[-CB-]

Tung oil would.  Shellac is interesting stuff, even works when painting metals.

Any time you have a coating though, it can peel.  Lacquer can peel.  Poly can peel.  Shellac can peel (not often).  Oils tend to not peel because its hard to build up enough to get a real film-like finish going.  I have done tung oil (pure) with a film like coating, but it was MANY coats.... MANY on a set of Ruger Security Six grips (a long time ago).