cocobolo finish problem 411

[FRANK]

well I am using nitro and it is not liking it very much the top was great the back and the head cap looks like oil and water ? yin and yang what could be the problem besides contamination in my gun doubtful ?

[Len Biglin]

Hi Paul , if it's forming fisheyes , sand it smooth wash with grease and wax remover (auto store) and cover with shellac (spraying seems to work)or brush and lightly sand.Then try again with the nitro, the nitro company probably has a sanding sealer also and they tend to cover better than laquer.But if you do use sanding sealer , make sure you sand it before the nitro , it's slippery and the laquer can peel off.Len

[Dave Yelverton]

Paul, I've never had a problem with cocobolo, but I haven't tried putting nitro on the bare wood. Usually put a wash of vinyl sealer or shellac 1lb cut and then follow by filling with epoxy and another washcoat after sanding down. Both shellac and vinyl sealer are good at sticking to waxy surfaces, but it wouldn't hurt to degrease with naptha or acetone as a belt and braces exercise. Had to refinish a Strat once which must have been exposed to silicone grease . It was fisheying like you wouldn't believe and degreasing wouldn't do the job. However two wash coats af shellac and the nitro went on like a dream.

Good luck

Dave

[Len Biglin]

Dave are you saying you use epoxy as a grain filler ? How do you apply it? and do you sand down to wood again?I am building again after a 6 year break Len

[FRANK]

yea dave whats going on there with the epoxy pleas tell us

[FRANK]

THANK YOU GUYS

[Dave Yelverton]

Mix up epoxy (rapid-setting. I use West's.) with micro beads or colloidal silica. Make it fairly stiff, then you can thin it down with alcohol to apply more easily. Use a credit card (expired preferably) to pack the mix into the grain, then to skim the surface. You want to remove as much from the surface of the wood as possible. To keep it moving you can use a hairdrier, but not set too high as you don't want the epoxy to go off whill you're moving it about. Hopefully you won't need to sand too much, but get rid of ridges and inconsistencies. You may need to do it more than once to get the grain completely filled. The advantage of this is you don't need to match the filler colour. The epoxy is near enough transparent when set. If you've got some neat way of holding the guitar, you can do the whole lot at once; otherwise wait until the front is set before attempting the back. Problem areas are at the heel; you have to work hard to stop leaving ridges on the curved surfaces. Seal with a shellac or vinyl wash otherwise I don't think the nitro adhesion is too good
Hope that's some use.

Dave

[FRANK]

great Dave off to the hobby shop cheers PHB

[Dave Yelverton]

Paul, don't forget to wear gloves, otherwise you might achieve a closer bond with your wife/girlfriend/significant other than either of you might desire!
Incidentally, I have heard of some builders using a high build polyester basecoat to provide a stable ground for laquer. I've never tried it and I would be interested to hear from anyone who has experience of this. I doubt if I could spray this stuff with my 1.4mm jet HVLP setup but perhaps someone could set me straight.

Dave

[FRANK]

ILL KEEP YOU INFORMED THEN I BOUGHT EPOXY WAS TOLD I COULD USE M.E.K. TO THIN IT OUT

[Dave Yelverton]

I use alcohol to thin the epoxy as I use a vinyl sealer on the bare wood and don't want a solvent which will cut through that. MEK will take out nitro, vinyl and many gums and resins, so may not be a good choice unless you fill the bare wood without a sealer. Meths or de-natured alcohol should do the trick.

Dave