More progress

[sebastiaan56]

Great outcome Bob! Sounds typical of Neil as well. His products are great, non toxic, well supported and for general woodwork info his forum is #1.

[James Mc]

I’m not sure if this is relevant or related but the old luthier who got me started only used one finish, French polish, and had been doing so for 40 years. He warned me about a similar issue with button lac, he wouldn’t use it on soundboards because he found that if you built it up to a good finish then it tended to craze after a few years. He thought it was probably ok to use on necks and bodies but he had his doubts so only use it on furniture (where it was his preferred finishing product).

I though this was worth mentioning because button lac is heat-treated to be harder than normal shellac.

Happily spraying shellac isn’t going to be an issue for me because I love the whole French polishing process. But for me it is only a hobby so time isn't a cost issue.

[kiwigeo]

I cant say Ive had alot of success French Polishing my latest classical with hard shellac. Its very likely that my technique is the issue but an earlier guitar I did with normal blonde shellac flakes went without a hitch.

I'm currently replacing the back on the latest classical after numerous failed attempts to get a good finish on same. I sanded back the finish and cleaned up with shellite assuming that oil trapped in the rosewood pores is the problem. I french polished again with hard shellac but got exactly the same result....tiny breaks would start to appear on the finish surface after a few hours. Pore filling was done with Z-poxy so maybe that is an issue with hard shellac.

Will be watching this discussion with interest.

[Paul B]

Nope, not an issue with z-poxy. I pore filled with TimberMate wood filler and still got crazing. No epoxy involved.

Just needs a dash of propylene glycol or similar to make it a bit more flexible.

Even if Neil adds a plasticizer like propylene glycol, you'd still be able to eat the stuff without ill effect. Can't say that about many other finishes.

We're on a winner, just needs a bit of tweaking is all.

[Dominic]

Hey, I really like hard shellac. I have finished an electric explorer guitar and added black stain for a black finish. I did use thinned about 40/60 meth/HS. That was a year ago and no cracking whatsoever. Finish is the same as I left it. Also finished 2 acoustics with it. Again no problems. Over time it seems to sink into the grain a little bit which i don't mind. i used Zpoxy filler sanded back to wood then sanding sealer then thinned HS sprayed on. Back and sides on both are EIR and have a nice hard shiny surface.

You guys should have a look at your techniques before giving up on it. The only other thing that I can think that I have done is that I have left plenty of time between recoating with light sanding in between and that I leave the finish on the tops very thin, maybe too thin for you guy who sell guitars. I like it anyway so i will be very interested to see what Neil has to say and if he can improve it.
Cheers
Dom

[Craig]

On reflection , I think I may have been a bit tough on Neil. I guess my dissapointment , and the thought of taking off the bridge and refinishing the lot,overcame me a little.

Bob asked me to send him some pics of mine ,( which I've just done) ,so he can have a look at it tomorrow when he visits , and maybe nail the problem.

It doesn't surprise me that a solid body finish behaves O.K. My headstock is also O.K.. It seems it's the thinner wood that is affected most. The thinner wood moving quite quickly with humidity changes.

A big thanks goes to Bob for his effort with this matter


Cheers, Craig

[Bob Connor]

Anyone else who has any ideas or theories please chuck 'em in here before Tuesday.

One thing that has become apparent talking to Paul and Craig is that there is no cracking or crazing on the necks, headstocks of these instruments ie it only happens on backs and tops (thin wood)

I don't think it's Epoxy fillers either. The two instruments of ours that have been affected it's only the tops. Plus Paul uses Timbermate for filling.

Bob

[Arnt]

Thanks for your reports on this, guys. I have said many times when I have seen your instruments how good your finishes looked, and I have been wanting to try it out out. Hopefully these problems can be worked out, I would really like to knock my nitro habit!