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I am almost done with the painstaking finishing process on my first acoustic...This one has been stubborn (I am trying SOO hard to get a thin finish)...

Anyway, thought I'd share...

I spray in my attic, then allow the guitar to vent out in my bathroom - which I can keep a little warmer (cost-effectively) and then vent quite easily...I use cat-poly which dries in a day or so, so it does not have to hang there when I am trying to take a shower

Stephen

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www.ziegenfussguitars.com

It looks good. Can you add any info on your Cat-Poly process?

Thanks for showing.

John

Yeah for sure...

The Cat Poly is an automotive clear coat manufactured by American Painter's Supply. It is essentially chrystal clear, but does exhibit just the slightest bit of amber when completely dry. I prefer this over perfectly clear coats because it adds a little bit of warmth...

After pore filling - for which I use colloidal silica laden west systems epoxy, I generally spray 2 coats at a time, about 25 minutes apart until I get a good "base". These coats are light as heck and really are nothing but a big orange peel. At this point, I lightly level the whole thing, mix up some new finish adding in about 1/6 laquer thinner...This creates a better chemical bond between the finish layers while also thinning the finish. I spray two more coats about 25 minutes apart - a bit heavier trying to prevent the capillary action in the finish - to prevent orange peel...But trying even harder not to get drips. If for some reason there is still a bit of orange peel, sometimes I mist the surface with lacquer thinner - which reduces the viscosity of the surface allowing the finish to "flow" just a little better.

Depending on temperature of drying, I wait between 8-24 hours to sand and level (or until I cannot leave a finger nail mark)...I wet sand, and if I go through, I add another two light coats to that section of the guitar geometry (i.e. if I go through on the sides, I will spray the whole set of sides with another two coats)

I am certainly not a professional, and would give up the frustrations of doing this step readily, but I am trying hard...It is just more difficult when you want such a thin layer for acoustics..

Stephen

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www.ziegenfussguitars.com

I'm getting the finish on number on and have found how wonderful and relaxing and enjoyable French polishing is 5 coats now so a few more days yet.

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Formerly JJH

I learn more from my mistakes than my successes

Oh my - a guitar hanging in a bathroom - brings back fond memories........

Stephen my friend your guitar looks killer in all respects!!!!

And this kind of excellent workmanship from a dark sider too......

There you go Hesh, speaking smack again...

Hopefully, sometime before 2010, I will be able to post finished pictures...

Stephen

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www.ziegenfussguitars.com

cat poly-what ???? urethane or ester ??? there is a big difference. Folks dont seem to be all that specific when talking cat poly.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Sorry Tony,
it is a poly-urethane. I am very limited in my knowledge, but I did not even know they made poly-ester auto finishes because I think it tends to break down in the presence of heat...

I believe poly-urethanes are actually part of the poly-ether family - which are thermoplastics whereas poly esters are thermosets...

Again, sorry for the ambiguity

Stephen

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www.ziegenfussguitars.com

I wouldnt be so sure about the breaking down in heat part ..... Mike Collins (the Cdn one) is shooting polyester, and the UV cure lamp is like 600 degrees F or something - you need full on welding suit/gloves and face shield to use it - and it doesnt burn up the guitar. Amaziing stuff.

maybe Joe White or Mike will chime in on that ....

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Is Polyester what people are getting when they have their finishes outsourced? I'm thinking of the great finishes I see coming from Joe White.

Is there a big difference between the Cat-Poly and UV-Poly in final product?

John

John, I am using Polyester and I think that Adam Stark does as well. Last time I talked with Tony Ferguson he was using Polyurethane. There are many different finishes available out there and plenty of finishers that know how to best take advantage of the particular product that they have chosen to use. With McFadden's, the only difference between the UV and non-UV is the added initiator that allows the UV light to cure the finish quicker. Some actually use the hardener/catalyst along with the UV lights for a "dual cure"
The cat cured polyester is plenty fast for my needs.

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jw ( o)===:::

Stephen...I think you have it backwards on the Thermoplastic vs. Thermoset thing.

Thermoplastics are generally more heat sensitive and reversible...they are PLASTIC and as such will melt into different forms.

Thermosets are generally crosslinked and cured by virtue of a chemical or UV catalyst (crosslinker) and not reversible and as a result have better heat resistance.

I'll leave it to Joe and the other finishers to speak for the comparative physical properties of Polyurethane vs Polyester finishes. I've seen both side by side and I'd pick the catalyzed polyester every time...and so would Taylor, Martin and many small boutique guitar factories.

I'd be interested in knowing how each finish compares on the issues of:

1) Hardness
2) Flexibility
3) Refractive index
4) Aging properties
5) etc.

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JJ
Napa, CA
http://www.DonohueGuitars.com

Yeah JJ....

The cross-linking of the thermoset means that in the presence of heat, the compound will actually break down, whereas thermoplastics simply loosen their structure...But all of this depends on temperature of degradation, etc....but we have the same understanding...

Thanks,
Stephen

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www.ziegenfussguitars.com