PVC & Nitrocellulose Lacquer: Do they react?

[John Cartwright]

Greetings, haven't been on in a good while, but I'm still here!

OK, so I have a question that is a bit off topic, but a little bit related on account the finish/chemistry issue I'm faced with. I hope it's OK that I'm asking here, I would have asked elsewhere, but I really trust you guys, and your expertise, so here goes...

I recently purchased a fantastic vintage desk by Standard Furniture Company, probably 1940's, and from solvent tests, it appears to be nitrocellulose lacquer (softens with lacquer thinner and a Q-tip, reacts only a little with alcohol and the same method) I'm currently reviving the the top with a light sanding to level, and a fresh French polish with de-waxed shellac from LMI. Now, I wanted to protect the top with a clear desk pad that showcases the grain but gives an extra barrier in the work area of the desk. After receiving the desk pad from Amazon, I see now that it is made with a semi-soft PVC. My first thought was 'great, I might as well throw a bunch of vinyl Ace guitar straps on there and wait for the melt!'

I looked up the differences between vinyl and PVC, and while they are related, they are different, but all technical notes I've read give me no clue as to whether or not it is safe to use this desk pad, or to send it back for a polycarbonate one.

Thoughts? ...and Thank You!

-John

[Frank Ford]

Since you're using shellac as the new surface coating over the old lacquer, I doubt you'll have any problem with chemical reaction.  The PVC won't be interacting with the old lacquer - it'll be touching shellac.  Just look under there from time to time and see what happens.  If there's a problem you can always add more shellac.    

The display counters in my shop take quite a chemical beating with everybody's hands and arms leaning on them, and the lacquer finish turned to tar in some areas years ago,  I scuffed them and added some coats of nice shellac - no problem since.

[John Cartwright]

Frank,

My wife informs me that her office desk, clearly finished with a more modern finish, could use the protection offered by this desk pad. I may opt to give it to her and find an alternative for the antique desk, to be safe. However, it's good to know that PVC can be a trouble maker too, and that shellac has yet another fine application to add to it's list of virtues. Good stuff, shellac!

I appreciate your input! Thanks!

-John

[Andrew]

The nice thing about french polishing the top is that you can always just give it a quick scuff and top up the fp again if it gets a little worn. Maybe you dont need a pad?

[John Cartwright]

With a nice buffing of Butcher's wax as an added layer of protection, you are likely right. The PVC pad, as I've found, looks a bit chintzy no matter the surface one places it on, so doing the naked thing might be best. Even if she doesn't use it for her work, I'm sure I can repurpose it - not worth the effort and cost to send it back.

Still, it's good to know to watch PVC as much as vinyl when it comes to nitro  As always, good advice here at Frets!  

Steering back toward the guitar side of the issue, does anyone here use French polished shellac on non-classical guitars? I'm not sure I'd use it on the back of a neck, but I'm intrigued by the idea of using it on an electric at some point. 

Thanks!

John

[Ned Knepp]

I don't know why it wouldn't work, John. Of course it's not a durable but it doesn't matter what you use it on, that's not going to change. 

 I've used it on mandolins and some parlor guitars when it's appropriate for the age of the instrument or on an instrument not worth enough to worry about originality. I honestly haven't had any issues with wear even on necks so far. I'm pretty careful with my instruments so I may not be a good judge. Even if it's an issue, shellac is so easy to fix that I'd use it anyway in these cases.

[John Cartwright]

I restored a 'basket case' Bay State back in 09 for a friend which was originally french polished, so once the back was repaired I used that method and shellac. It was my first FP job - aside from the practice work I did on scrap leading up to it - and it came out great. I loved the process, the fact that it's much better for health and planet and it's kinda fun too. Just never heard of anyone using it much, especially on an electric. I might give it a go on my next frankincaster. 

My great uncle Eugene knocked over a glass of Jim Beam onto my grandma's french polished coffee table (she was less than thrilled) so she had the top refinished. The guy used a satin varnish or poly, and while he did a fine job executing the task, it is no where near as pretty as it used to be. Maybe it's me, but there is something unique about the way it reflects and refracts light ...or something. Maybe it's just the romance of it. Anyway, that's got nothing to do with the discussion, but hopefully an interesting anecdote, at least. :-)

[Ned Knepp]

I agree with you about the look. I really like the process but it's the look that makes me want to keep using it. 

 I have the skill to spray finish ( when I have the right equipment) since I grew up doing that but the process of FP really appeals to me. I don't have to rush, since I'm not being paid for my work anyway and I can get it started and think about other things while I work. I find quite soothing.

When it's all said and done, I love the "almost" bright shine I can get without buffing. Sometimes I buff it out but sometime I leave it there. It''s not a satin finish but it not a deep gloss either. Either way I think it's unique too. 

BTW I like to use carnauba wax on my FP finish because of it's hardness. I feel that it helps with the "less robust" nature of shellac. I have an ancient can of Mother's carnauba wax that doesn't have silicone in it but it's almost gone. I've had it for decades and only use it for thing that I want the hardness factor on. ( works for my saw table too.)  I don't know if Mother's still make it that way or not but I'm going to need to find a replacement soon. Anyway, in my estimation, it's been a very good compliment for my FP finishes.

BT-BTW, I did some experimenting with lacquer thinned enough to "FP" a finish. It didn't work like shellac, probably because lacquer thinner doesn't evaporate as quickly as alcohol but it wasn't too bad either. It WAS much harder to get a build without stripping at the same time. It definitely didn't like a lot of pressure on the pad or the existing finish would start to "roll up".  I was never able to get a good even shine so, since it was on a cheap mandolin that was small enough to use it, I powered up my airbrush to spray a couple of "finish" coats to complete it.

I think it MIGHT work with patience and, perhaps a different, fasting drying solvent but I haven't returned to my experiment yet. I don't know of there is a lacquer out that that could be thinned with alcohol of if there is a similar solvent that would work in it's place. It's just one of a long list of things that are low priority.  

[John Cartwright]

Ned,

I have some paste wax by a brand called Staples. It's been pretty good for me, but I like my can of Butcher's Bowling Alley Wax better - seems to dry harder, though the turps are stronger. Both have carnauba, but both use other waxes too. These aren't named, so naturally you don't know how much of which wax is used. I'll look up Mother's and see what I find. It's always a tough thing to face when a beloved product might well be OOP.

Wax is also underrated, in my opinion. I gave a new setup, pickguard and knobs to my Fender Malmsteen strat (the one you guys helped me with when refretting it - thanks again!) and I used a little wood stain and the Butcher's to add some depth and antiquing to the knobs and pup covers after scuffing 'em up a bit.  Very versitile stuff!

[John Cartwright]

(side note on the Malmsteen Strat: Tried out Fender's "grease bucket" tone circuit. HIGHLY impressed, but I digress...)

[Ned Knepp]

I've looked at a couple sites that have information about home brewing wax. I may give that a try sometime but I don't think I want to experiment on my instruments until I'm pretty sure it works.

 I haven't heard of "Butcher's bowling Alley Wax" before. I'll look it up.

[John Cartwright]

Ned, 

I just added a product called Lundmarks clear paste wax to my Amazon wish list. It claims it's just a mix of carnauba and turps. It's pretty cheap, and might be worth a go. If not ....who knows, it might make a nice pomade. Ha! :-D

While on the subject of shellac and wax and such, I have a jar of de-waxed ruby shellac I mixed up in July of '09 (I wrote the date on it) and I know this stuff isn't supposed to last long on the shelf, but I've tried the 'glass test' two or three times just for the heck of it, and it dries nice and hard, not gummy at all! Is it risky to use it, or do you figure it's OK? We are only talking about 7-9 oz., so it's no big loss, but if it's still good, waste not, want not.

[Robbie Collins]

You could always glue some felt to the bottom of the desk pad.