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Problems with epoxy filler under nitro
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=21619		 Page 1 of 1
Author:  Rvsgtr [ Tue Mar 24, 2009 10:09 am ]
Post subject:  Problems with epoxy filler under nitro
Anybody had any troubles with epoxy filler, as in around inlays, showing through the nitro? It seems the lacquer looks a little rippled around the edges of some inlays I've done and its where the epoxy based filler is. This is after normal application/build and one week cure time before buffing. Its not in dips or valleys. I've always used Smith's All Wood epoxy but have recently switched to McFaddens nitro. I'm hoping a good build and longer cure time will solve the problem or I'll have to redo this finished neck which don't sound like fun. Any help would be greatly appreciated.

SR
Author:  Michael Dale Payne [ Tue Mar 24, 2009 10:15 am ]
Post subject:  Re: Problems with epoxy filler under nitro
many things have issues sometimes adhearing to epoxy. that is why I always seal epoxy with shellac
Author:  Barry Daniels [ Tue Mar 24, 2009 11:39 am ]
Post subject:  Re: Problems with epoxy filler under nitro
Could be insufficient drying time with the McFaddens (one month is whats recommended) or insufficient curing time with the epoxy filler. Is this on a fretboard?
Author:  Rvsgtr [ Tue Mar 24, 2009 3:22 pm ]
Post subject:  Re: Problems with epoxy filler under nitro
It is for a peghead and the inlay was done about 3 weeks ago so the epoxy should be cured all it is going to do. I thought about the shellac thing only after I tried buffing. The rest of the peghead looks great just right around the inlay and it looks like it should after wetsanding down to 1000 which is my normal protocol. You can't tell a thing until it is buffed. Now I don't know whether to strip it to wood and use the shellac or just count on the cure time solving the problem. The entire project, and its future owner, wait on this issue unfortunately. Any other inlay guys out there that has seen this?

thanks guys for your replies, BTW.
Author:  Rvsgtr [ Tue Mar 24, 2009 5:23 pm ]
Post subject:  Re: Problems with epoxy filler under nitro
Sorry Filippo. I'm not very computer literate and couldn't figure out how to change my username.

I did use Mcfaddens sealer first...several coats. Then my normal routine for the lacquer. Something either chemically between the epoxy/nitro/sealer is going on or it's an adhesion issue. I never had this problem with Behlen's sealer or lacquer for some reason. Have always used epoxy to inlay.

I like the Mcfadden's but can't say it is any better and this issue is going to make me go back to Behlen's I think. I only use lacquer for pegheads now (just for durability) and almost always use a french polished finish everywhere else unless the customer requests nitro.

I just scraped the finish off and sanded in preparation for the shellac. I will try that and pray it pans out. Thanks.

Steve R
Author:  TonyKarol [ Tue Mar 24, 2009 6:00 pm ]
Post subject:  Re: Problems with epoxy filler under nitro
Having used both McFaddens and Behlens (Mohawk is the mfr), I cant see how you wont get some shrinking back into the pores after buffing the finish after only a week of curing. I use Zpoxy and still get some after a while, and thats with 3-4 weeks of cure. Its looks like glass for a bit, but still sinks. Thats nitro.

For pore filling headstocks, I like to use thick CA, razor blade it on. Fast, and easy to add more if reqd.
Author:  Aaron O [ Wed Mar 25, 2009 11:57 pm ]
Post subject:  Re: Problems with epoxy filler under nitro
I use West Systems to fill, and I've used CA in the past. No problems with either, shooting McFaddens over both. (boy, that sounded like Yoda, didn't it?)

Steve, do you thin your nitro, or shoot straight? Part of what's bothering me in your process is the fact that you said "couple" of coats of sealer.

FWIW, when shooting nitro I usually just shoot a tack coat, then start spraying, 3 coats a day, 45-60 minute spread, depending on the weather. I've used sealers in the past, 2 light coats, then sanded back down. Sort of doesn't make sense (to me).

Also, not that nitro would use a mechanical bond like poly, but what is your final grit on the inlay?
Author:  TonyKarol [ Thu Mar 26, 2009 7:18 am ]
Post subject:  Re: Problems with epoxy filler under nitro
Cant say I ever had probs with nitro over CA either ... I was usig a Mohawk sanding sealer on a couple guitars, but that stoppped when I discovered that the nitro didnt stick to it all that well .. it would give the grey/opaque blister look if you knocked the guitar on something. Nitro right over the Zpoxy for me now.
Author:  Rvsgtr [ Thu Mar 26, 2009 4:17 pm ]
Post subject:  Re: Problems with epoxy filler under nitro
FWIW, I use two thinned (50/50) coats of sealer, wait 24 hours then on to the nitro. Been doing that for years and alot of refinishes, new guitars, etc.

Also, doesn't make sense why you would use sealer and then sand "back down". Is that to the wood? That would defeat the purpose of sealing.

Since I'm not sure anyone really gets the gist of what is happening I will just say this...after sanding the peghead, which is ebony inlaid with pearl "things", to 220 the inlay, filler it was inlaid with and wood is all nice and smooth. After shooting two thin coats of the sealer the epoxy seemed to raise up and feel rough around the edges of the inlay. Almost like it swelled up. I have just done the shellac and it seems to have done the same thing maybe not quite as much. I'm going to go ahead and shoot the nitro as normal and wait 3-4 weeks. If that doesn't work I'm going to be heartbroken, broke, and building a new neck I reckon. [headinwall]
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