Polyester basecoat with nitro-cellulose topcoat - What's the point?

[tildeslash]

Really what's the point of this?
Does it offer anything of value in protection or just a talking point that "hey it's nitro?"

hmmm......not sure what to think of this?

 

[kennymac]

I've been doing a lot of research in guitar finishes and it seems to me that the color base coats are only supposed to be only heavy enough to cover, that's it. The nitro clear coats are there to provide the top coat that eventually gets buffed out to the high gloss shine.

Check out the stewmac videos by Dan Erlewine and Don MacRostie, they outline the process pretty well.

Again, I've only been researching this and do not have experience to speak from. I have a guitar that I am building where I am right at the finishing stage, so I've really looked into this a bunch.

 

[Bob V]

Really what's the point of this?
Does it offer anything of value in protection or just a talking point that "hey it's nitro?"

hmmm......not sure what to think of this?

What's the point of asking? Do you have something against the word "poly"? Your question seems to suggest that polyester ruins the value of having nitro, but maybe I misunderstand the post. There certainly is an advantage to a nitro topcoat, but it's not the end all and be all of wood finishes. Nitrocellulose lacquer is pretty. It's very easy to spray and get good results in different conditions of temperature and humidity, you can gum up a coat really badly and just shoot another layer and it will all smooth out, you can recoat almost immediately without a curing window, it doesn't clog the gun very often, you can leave it in the sprayer for like a year without cleaning the gun so long as you keep using it regularly (ok an exaggeration). The point is the stuff is very forgiving to use, and the results are great. Some people also like the idea that certain nitro finishes can be coaxed into flaking and checking if the "relic" thing is your bag. So, what's the point of nitro? Plenty. Mind you, it's not what I use to finish woodworking projects (including guitars) as a hobby, but I will use it to repair a guitar or piece of furniture that has it already.

Now theres the poly situation, long story there. There's the undeniable fact that cheap import guitars have poly-something finishes on them. This gives it a stigma, so much that people react to the idea of a polyester undercoat as if it devalues the guitar.

The sealer and color coats have their separate jobs to do, and nitro isn't necessarily the best stuff in those applications. Commonly nitrocellulose lacquer is formulated in a product line that also includes a vinyl sealer for use as an undercoat.

Also consider that the drawbacks of nitro are sometimes cherished when they become part of a vintage finish. When I do a piece of woodworking I don't want the finish to shrink and have the grain print through in a year, so I use a polyester or acrylic undercoat before I do the clear topcoat. If you wanted to replicate the mojo of a shrunk-back finish on a vintage guitar, then you're going to be going about it a very different way.

 

[doublee]

I think maybe the OP was wondering, or maybe I am wrong, is why say for example Fender bothers to put nitro over poly as in the Tele 52 RI....why bother with the nitro at all?

 

[BBender]

I don't really know...but I get the feeling that they did it because that is what people are into right now....the whole "nitro" thing. I would think that having a Poly undercoat would defeat the purpose of the nitro...if you are looking for the resonance factor. Nitro is supposed to make the tone of the wood come through....so having a suffocating layer of poly to start and then spraying nitro on top would defeat this whole purpose.

Maybe I am wrong...

 

[outtahear]

I think maybe the OP was wondering, or maybe I am wrong, is why say for example Fender bothers to put nitro over poly as in the Tele 52 RI....why bother with the nitro at all?

Tradition?

FENDER used Fullerplast as a sealer in the 60s w/ Nitro and acrylic lacquer color, and nitro topcoats.
Ever hear some motherfu@ker drone on about how custom color 60's Strats just don't have the tone of earlier bursts?







Me neither.

 

[mattmccloskey]

Bob V hit on it. Undercoats are there to fill grain, seal the wood, provide a level base on which to build.

A pure nitro finish, which is rare, shrinks, and shrinks, and shrinks... you end up with a dimply and rippled surface, unless of course you do tons of sealer coats with lots of sanding over the course of months. Even then some shrinkage occurs.

If you want a mirror surface, something more stable needs to seal and level the wood. This actually makes it possible to shoot less paint because it doesn't keep shrinking into the wood and requiring more and more nitro to level it.

 

[tildeslash]

What's the point of asking? Do you have something against the word "poly"? Your question seems to suggest that polyester ruins the value of having nitro, but maybe I misunderstand the post.

I ask to learn.
I have nothing againt poly - I love it - it protects.
Yes you did misunderstand.
But I loved your explanation.

I think maybe the OP was wondering, or maybe I am wrong, is why say for example Fender bothers to put nitro over poly as in the Tele 52 RI....why bother with the nitro at all?

Yes why bother at all.

If poly protects and you have nitro on top you're not really getting the nitro effect - it's like sex using a condom.

I understand why manufacturer do it but it seems illogical.

With the relic thing I understand that you're simulating wear and tear.
But with nitro over poly - that just baffles me.

 

[mattmccloskey]

I ask to learn.
I have nothing againt poly - I love it - it protects.
Yes you did misunderstand.
But I loved your explanation.



Yes why bother at all.

If poly protects and you have nitro on top you're not really getting the nitro effect - it's like sex using a condom.

I understand why manufacturer do it but it seems illogical.

With the relic thing I understand that you're simulating wear and tear.
But with nitro over poly - that just baffles me.

you seem to be missing something though - fenders always had a non-nitro undercoat from the late 50's on.
You are assuming that there is a 'nitro effect'. The only effect is that you can get a certain patina over time to the finish, yellowing characteristics, checking - this will still happen even with a poly undercoat - for example on an early 60's strat (with fullerplast poly undercoat).

 

[Stike]

Yes why bother at all.

If poly protects and you have nitro on top you're not really getting the nitro effect - it's like sex using a condom.

I understand why manufacturer do it but it seems illogical.

With the relic thing I understand that you're simulating wear and tear.
But with nitro over poly - that just baffles me.

I think Bob V explained it very well. What specifically do you find illogical?

The sealer and color coats have their separate jobs to do, and nitro isn't necessarily the best stuff in those applications. Commonly nitrocellulose lacquer is formulated in a product line that also includes a vinyl sealer for use as an undercoat.

Also consider that the drawbacks of nitro are sometimes cherished when they become part of a vintage finish. When I do a piece of woodworking I don't want the finish to shrink and have the grain print through in a year, so I use a polyester or acrylic undercoat before I do the clear topcoat. If you wanted to replicate the mojo of a shrunk-back finish on a vintage guitar, then you're going to be going about it a very different way.

 

[GtrDr]

Manufacturers are trying to make the Finnish as thin as possible but offer durability as well. The base coat wont fade out, it's also thinner than a base coat / clear coat system. The lacquer makes for a brilliant finish and it's thin & it's easy to fix scratches. Sounds like a great solution.

 

[Keyser Soze]

...
If poly protects and you have nitro on top you're not really getting the nitro effect ...

You are still getting the effect of a nitro topcoat.

Please note that in my book this effect is strictly visual, but it is noticeable.

Poly looks like poly (plural would be more proper.) Shellac looks like shellac, Nitro lacquer looks like nitro lacquer. They all have different visual characteristics - depth, sheen, gloss, the way they respond to rubbing out and polishing, the yellowing, and or aging, etc.

Sure, you could stop at poly (or use a poly topcoat) but then the topcoat would not look like nitro.

It's that simple and nothing more.

 

[57special]

actually, not all lacquer looks the same. Some is very clear, some has anti yellowing agents, plasticizers, etc.. Some shellac has wax in it, some not.

It is possible to go all nitro (but WHICH Nitro?) with closed pore woods quite easily, but it's another matter when finishing Mahogany, Ash or other open grained woods. You can use oil based fillers like Gibson did in the old days, or water based fillers, but you must use some sort of grain filler if you want a smooth finish.

To me it's mainly a matter of proper application rather than the specific material that's used. The horrid, thick Poly finishes used in the 70's by Fender, Music man, etc. shouldn't be considered as benchmarks.

Having said that, when I become President my first act will be to outlaw any finish but shellac.

 

[Stike]

Having said that, when I become President my first act will be to outlaw any finish but shellac.

As a fan of all things metalflake you will not have my vote.

 

[Keyser Soze]

Shellac is the all-purpose-sticks-to-anything finish. And it can be sprayed.

So, conceivably it could be used with (or more simply on) metalflake.

I could live without nitro, life without shellac would be tough.

 

[MikeMcK]

I ask to learn.
If poly protects and you have nitro on top you're not really getting the nitro effect - it's like sex using a condom.

And that right there is the can of worms... what exactly is the "nitro effect"?

Some think it's a significant part of a guitar's sound, and some think it's all in the mind of the owner. Lots of people insist on pure nitro finishes "like they used to make 'em" on high-end guitars, even when they're replications of guitars that weren't even close to being pure nitro.

Whether it's important is a decision made by the owner, but some previous posters have brought up some oft-ignored facts.

 

[pyt]

It seems the real issue is less the type of finish and more how the finish is applied. Older fenders generally had reasonably applied finishes and that seemed to correspond with a good sounding guitar. When fender went with thick poly finishes, that seemed to correspond with not so good sounding guitars.

I prefer a nitro top coat because I like how it looks and feels. But I agree, from my limited experience finishing a body, that a solid base coat is desirable because you do have to apply more and more nitro to mitigate the shrinking effect. If a thin finish is the goal it's really a mixture of different finishes that will provide that result.

With that said, I had a fender nitro-over-poly Strat body. Looked great, sounded like crap. On inspection you could tell it did have a thick poly undercoat. But, my early 80's Jazz Bass 60's reissue appears to be all poly. It's not a thick heavy finish and it's a great sounding instrument.

 

[vortexxxx]

The nitro available these days isn't the same as the vintage bad for your health and ozone stuff. Another can of worms....

 

[GM Reszel]

As I understand the question of the original post it would pertain to the sound. If you believe that finish thickness makes a difference, less is better. If you're like the guy that turns the gain to 10 it's less relevant.

But I'll never forget when I was stripping the thick plastic off my IMC Charvel. Including fill the coatings totalled about 3/32" thick. I had not set out to change the sound, I was just a kid wanting a bare wood body that I could put stickers and cigarette burns on. When I strung it back up it was a very different sounding guitar (even on 10 the harmonics were much more prominent).

 

[homerayvaughan]

Bob V explained it best, but here's my .02 uninformed opinion. Does sealing a body with a poly undercoat mean that all potential resonance is gone? The poster above me also referenced the thickness as being a factor, regardless of the type of finish. So if conventional wisdom (for some) is that nitro is better and thinner is better, what difference would a base coat make if it is just that, a thin layer "base" coat, whether it's poly or not? And I feel Fender does the reissues/relics with nitro because that is what was used originally, even if the formulas today are different. It will show wear more quickly if that is something you are looking for.

1000th post - YIPPEE