Nitro vs poly on a semi hollow

danishbacon

According to Andertons:

Many purists and luthiers therefore believe that a nitro finish allows a guitar's wood to breathe, yielding a more open sound and greater sustain. Although nitrocellulose lacquer may give a guitar an airier sound, its softer texture does make it susceptible to cosmetic damage.

My question is this, given that a semi hollow is not finished on the inside and it is very much open, does this theory not hold for semi hollows as they can still ‘breathe’. 

Note this is a semi-serious post about semi-breathable guitars. 

ICBM

Given that the whole premise is nonsense anyway, does it even semi-matter?

GoldenEraGuitars

Isn’t the wood used for a guitar dead and dry? Does it really breath? 

p90fool

If you want the "greater sustain" nitro gives you, buy a solidbody.

WezV

A semi hollow made from Ply, like a 335?

Seziertisch

There was a discussion the gretschpages (I think) and a well-respected restorer/refinisher of guitars by the name of Curt Wilson opined that the issue with a poly finish on a laminate guitar is that the wood expands and contracts to a certain extent while the finish doesn’t. By comparison nitro is apparently a bit more flexible

crunchman

Nitro feels nicer and looks better when it ages.

I'm not sure it's inherently better tone wise than a thin poly finish. I don't think a thick poly finish helps any guitar.

Sassafras

Spray your face with a gallon of nitro and then see how well you can breathe.

Seziertisch

crunchman said:

Nitro feels nicer and looks better when it ages.

I'm not sure it's inherently better tone wise than a thin poly finish. I don't think a thick poly finish helps any guitar.

That's the thing, nitro feels nicer and the feel is a huge part of the cues that contribute to the enjoyability of playing an instrument.

Also, the issue with poly is that with any damage to the finish, it looks like a brand new guitar that has this one scratch or ding even if the guitar is 30 years old. Nitro is more forgiving in so far as aside from it being more susceptible to picking up dings, the finish itself ages in such a way that scratches and dings tend to look less out of place 

Whitecat

Pretty hard to take seriously any statement which begins with "According to Andertons" ...

Sassafras

FFS!
There's a big difference between polyurethane and polyester.
When will people differentiate between the two?

Kalimna

Wood only 'breathes' in the sense that it expands and contracts with humidity changes - so yes, if one surface is unfinished and open to the atmosphere, then it will allow the wood to 'breathe' whatever is on the other side.

Regarding anything other than durability and aesthetics, a thinner finish is better than a thick one. The type makes no difference.

There will be a differential across the thickness of the wood (be it solid or laminate) in expansion/contraction if only one side has finish applied, but I would not want to comment on any effect that will have.

Adam

ICBM

WezV said:

A semi hollow made from Ply, like a 335?

It would be interesting to know what the glue between the ply layers is made from...

crunchman said:

I'm not sure it's inherently better tone wise than a thin poly finish. I don't think a thick poly finish helps any guitar.

Exactly.

Seziertisch said:

Also, the issue with poly is that with any damage to the finish, it looks like a brand new guitar that has this one scratch or ding even if the guitar is 30 years old. Nitro is more forgiving in so far as aside from it being more susceptible to picking up dings, the finish itself ages in such a way that scratches and dings tend to look less out of place 

This is simply not true. It all depends on the thickness of the finish. Polyurethane can be sprayed very thinly and then it wears very much like nitrocellulose, just a bit more slowly - it can even check in a very similar way. I have posted proof of this more than once .

Example -



For what it's worth polyurethane is also water-vapour-permeable too, just a little less than nitro - how much is very dependent on the thickness and number of coats - so the idea that "nitro allows the wood to breathe and poly doesn't" is nonsense in the first place.

https://www.fpl.fs.fed.us/documnts/fplrp/fplrp462.pdf (Warning, this article is very heavy going!)

It is true that poly*ester* is much harder and even when applied very thinly it does tend to chip and crack rather than wear - as far as I can see it's not mentioned in that article and I don't know what its permeability is, but I would guess less than polyurethane.

I know I'm fighting a losing battle on this, but there is no such finish as "poly", and no-one outside the guitar world will understand what it's supposed to mean. It's become almost entirely just another term that's used for snobbery and marketing, even if quite a few "nitro finish" guitars didn't have it applied over a base coat of polyester anyway... intentionally to seal the wood.

NelsonP

Sassafras said:

FFS!
There's a big difference between polyurethane and polyester.
When will people differentiate between the two?

OK then.

Polyurethane


Polyester

prlgmnr

Many people Make Up Unfounded Shit when it comes to discussing construction and finish of Electric Guitars, most often in an attempt to Charge More Money for What They Were Going To Do Anyway.

Corvus

Seziertisch said:

There was a discussion the gretschpages (I think) and a well-respected restorer/refinisher of guitars by the name of Curt Wilson opined that the issue with a poly finish on a laminate guitar is that the wood expands and contracts to a certain extent while the finish doesn’t. By comparison nitro is apparently a bit more flexible

That's plain wrong though, 2k/urethane finishes are every as flexible as nitro if not more. E.g. car bonnets/doors can take quite a dent before the paint cracks. It makes zero difference anyway.

Funkfingers

Simple test.

• Grab nearest convenient hollow or semi-hollow guitar.
• Peek into any sound hole. (One of those dental mirrors on a stick would be useful.)
• Observe raw wood surfaces of back, sides, centre block and top.

The unsealed wood can "breathe". It can also retain moisture, decay or go mouldy.


I have electric guitars and basses in both nitro and poly finishes. I have a few self-builds finished in wipe-on materials. My preference is for nitro-cellulose, mainly because I like the smell. Perhaps, I should just by bottles of that to perfume all my guitar cases?

rossi

I have a simple theory .If you like it ,it sounds OK and it suits you ,just play it  and bollox to the rest .

Corvus

Re breathing. Years back cars were painted in nitro and they didn't all rust at the first sign of rain because of any breathing.

Btw the modern topcoat is usually two-pack, called catalysed urethane in the states. Polyurethane is really something else altogether. Except some places, even Fender, unhelpfully conflate the two because of use of the word 'poly' in the guitar world.
To add to confusion some Fender necks are actually catalysed polyurethane while bodies are urethane.
When polyester comes into it it's usually a very thin colour coat that sits underneath a 2k / urethane clear coat.

It's a right horrible mess of terms, not least because us and the US use different terms and then there's guitar-speak adding to it. But either way, this 'breathing' myth is a load of old chuff.

crunchman

This whole "breathing" thing and moisture content seems to be a bit a of red herring anyway.

Wood does change over time but it's more to do with things like cellulose and lignin.

I can only see the abstract of this paper, but I supect it would be an interesting read:

https://www.sciencedirect.com/science/article/abs/pii/S1296207412000404

lysander

@Crunchman pro tip : stick the above link into sci hub