Poly on binding

[brandonwhite]

Hi,
I've developed a process that I like for finishing my guitars, which involves doing a good clear layer of polyurethane before I apply the nitro color coat. Makes for a nice, hard substrate.

However, I'm doing a guitar with binding now, and the poly is peeling off the binding as I sand the body. Is this supposed to happen with poly? I've seen several poly-finished guitars with binding, so I wonder if I'm doing it wrong...
Any tips?

 

[Gary Gretsch]

First of all I do not know where you got this idea because it sounds like you made a mess of things. You can not put nitro over poly. My guess the poly nitro and plastic binding had a bad effect and do not bond. My guess you are going to have to strip the guitar and start over. I would use all nitro or all poly and not miss match.

 

[brandonwhite]

First of all I do not know where you got this idea because it sounds like you made a mess of things. You can not put nitro over poly. My guess the poly nitro and plastic binding had a bad effect and do not bond. My guess you are going to have to strip the guitar and start over. I would use all nitro or all poly and not miss match.

You can do nitro over poly, but you can't do poly over nitro.
I'm guessing you're correct that the binding and the poly aren't bonding though.

 

[NoTeleBob]

Isn't binding always scraped clean afterwards?

 

[brandonwhite]

Isn't binding always scraped clean afterwards?

Color coats are scraped off of binding; clear coats are not.

 

[Gary Gretsch]

Don’t Put Nitro Lacquer Over That Polyurethane Finish [Here’s Why…]

Nitro lacquer is more than just guitar paint. It’s also used on cabinets, desks, chairs, and much more. But, can you apply nitro over a polyurethane finish?

www.thewoodworkplace.com

But you can try to do whatever you want.

 

[schmee]

You are on shakey ground putting Nitro over Poly. The lacquer can deteriorate poly and make a mess.
But yes, it can be done IF the poly is good and hard AND the nitro first coats are thin, flashing off too fast to effect the poly.

As far as binding goes, I would expect the thin finish to sand off pretty fast on it. If I finish a bound neck I expect to take it off almost to the edge of the binding with find sandpaper..

 

[PixMix]

Don’t Put Nitro Lacquer Over That Polyurethane Finish [Here’s Why…]

Nitro lacquer is more than just guitar paint. It’s also used on cabinets, desks, chairs, and much more. But, can you apply nitro over a polyurethane finish?

www.thewoodworkplace.com

But you can try to do whatever you want.

In fact most nitro finished Fenders employ a poly type base coat. I have a '52 AVRI Tele that has had some finish wear, a nice and thick layer of polyurethane is peeking through.

Poly makes a great base for nitro. I have done it myself with great results.

 

[bparnell57]

Fender has been putting poly and other non-lacquer finishes under their Nitro for decades. I believe since 1963 they used a poly variant under all nitro finishes.

 

[Freeman Keller]

Hi,
I've developed a process that I like for finishing my guitars, which involves doing a good clear layer of polyurethane before I apply the nitro color coat. Makes for a nice, hard substrate.

I have no experience with any poly finishes (of which there seems to be many) but I do have lots of experience with lacquer and binding. It sounds like you are applying the poly as some sort of base coat, possibly to fill pores and to level the surface. A far better choice would be vinyl modified lacquer which is intended as a base coat under nitrocellulose lacquer and is completely compatible. If you need to fill pores use something that you know is compatible and have tested on scrap.

Normally I will do any pore filling necessary (I use a finishing resin called Zpoxy). Sand level, do any staining, shoot the vinyl sealer. Shoot the color lacquer over that, then scrape back the binding (you can do a certain amount of masking but I scrape the small surfaces. Finish with the clear coats of lacquer over both color and the scraped binding - 6 or so coats will reduce the little ridge to nothing. Wet sand and buff as usual.

I really don't know much about polyurethane finishes but I do know that there are both water and oil based, catalyzed and non. It would scare me to put any oil based finish under solvent lacquer - I think that is asking for trouble but I've never tried it so I can't say. I can tell you that the steps outlined above will work with no problems.

Here is a maple guitar (no pore filling) that has been finished with vinyl sealer and red lacquer. I'm scraping the binding back to plastic

And clear over that

 

[brandonwhite]

I have no experience with any poly finishes (of which there seems to be many) but I do have lots of experience with lacquer and binding. It sounds like you are applying the poly as some sort of base coat, possibly to fill pores and to level the surface. A far better choice would be vinyl modified lacquer which is intended as a base coat under nitrocellulose lacquer and is completely compatible. If you need to fill pores use something that you know is compatible and have tested on scrap.

Normally I will do any pore filling necessary (I use a finishing resin called Zpoxy). Sand level, do any staining, shoot the vinyl sealer. Shoot the color lacquer over that, then scrape back the binding (you can do a certain amount of masking but I scrape the small surfaces. Finish with the clear coats of lacquer over both color and the scraped binding - 6 or so coats will reduce the little ridge to nothing. Wet sand and buff as usual.

I really don't know much about polyurethane finishes but I do know that there are both water and oil based, catalyzed and non. It would scare me to put any oil based finish under solvent lacquer - I think that is asking for trouble but I've never tried it so I can't say. I can tell you that the steps outlined above will work with no problems.

Nice! Thank you for the tips. The poly I'm using is water-based, so that's good. In the past, it's been a great grain filler for me. Sands down really level and makes for a hard base to put the nitro on. Problem now is that it's not sticking to the binding on this one. I managed to strip all the poly off the binding. The poly on the wood is solid and smooth. I guess I'll just hit it with some vinyl and spray nitro over that. Might be a tiny lip from the poly to the binding, but that shouldn't be too big an aesthetic issue.

Do you find your vinyl sealer bonds to the binding just fine?

That red 335-ish guitar looks real nice. Did you build it?

 

[brandonwhite]

Here's a previous guitar I built (without binding) if anyone is curious about using poly as a base coat. It's been around for a few years, and no problems with the finish. I guess time will tell if there are any latent negative effects.

 

[Freeman Keller]

Thank you. I have used Behlen vinyl sealer on almost all of my guitars now under both Behlen and Cardinal lacquer. I've used PVC, ivoroid and wood bindings, almost always attached with CA. I scrape binding before finishing (rather than sanding). My only other experience has been with water born lacquers, which I no longer use. I have absolutely no experience with any poly finish.

I've had no issues with bonding. I did have once guitar where the lacquer chipped away from the wood (maple), in that case I had not used vinyl sealer but had thinned the lacquer and shot directly onto the wood. Since then I have always used the sealer (a couple of early guitars I sealed with shellac, they came out fine too).

Yes, I have built two semi hollow 335 style guitars. Interesting critters with the pressed laminated tops and backs.

 

[Gary Gretsch]

I believe Fender uses a 2 part Catalyzed product called Symtec Sealer. I may have spelled it wrong. It works great for a grain filler and sealer and. It is very expensive and can be top coated with anything. I have used it. and have never had a problem with it.

 

[dsutton24]

Well, back to the OP... You're throwing a lot of half-terms around. I'm assuming that you're talking about polyurethane over the binding. You see a lot of talk about Fender and their 'poly', a lot of their 'poly' finishes are actually polyester.

Is the binding ABS? If so, that's the problem. ABS plastic is very slick and not at all porous, so there's no tooth for the polyurethane to stick to. I know in the automotive world there are special primers for use on ABS, but that's of no help when clear coating.

Since you're going to spray lacquer (I assume) anyway, I'd scrape the Polyurethane from the binding and overspray as usual with your lacquer.

 

[brandonwhite]

Well, back to the OP... You're throwing a lot of half-terms around. I'm assuming that you're talking about polyurethane over the binding. You see a lot of talk about Fender and their 'poly', a lot of their 'poly' finishes are actually polyester.

Is the binding ABS? If so, that's the problem. ABS plastic is very slick and not at all porous, so there's no tooth for the polyurethane to stick to. I know in the automotive world there are special primers for use on ABS, but that's of no help when clear coating.

Since you're going to spray lacquer (I assume) anyway, I'd scrape the Polyurethane from the binding and overspray as usual with your lacquer.

Yeah, my binding is ABS. Makes sense. I think I'm going to do as you suggest here.

Regarding the Fender finishes, I had heard that fender uses polyester on the Mexican models, but polyurethane on their American (non-nitro) guitars. I don't really know if that's true or not.