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[QUOTE=Hesh1956] Dave White made a post yesterday in which he stated that he has done some work to see what the tonal differences might be and that he likes leaving a thin coat on certain kinds of wood.[/QUOTE]

Hesh,

As Al Carruth so wisely and so often points out, the easiest person to fool is sometimes oneself .. BUT I'm beginning to think there is something good going on as:

- For backs and sides, when the thin Z-poxy coat is on (and I am tending to use 50/50 Z-poxy alcohol from the go) and I rub it back with 0000 wire wool leaving a thin film, apart from it looking good, the change in pop and projection that comes out of the instrument when you tap both top and back is - to my ears - remarkable.

- My cedar/maple Samhain that I love so much was originally finished in FP but my arm was re-acting with the finish in a bad way over the lower bout. So I stripped of the FP and re-finished in Z-poxy on the back and sides and a new pre-catalysed lacquer I have found on top and b/s. Not only did I love the way the Z-poxy brought out the maple, but the sound improvement of the guitar was immense - and it was already a great sounding guitar. Now it could be that the top went a little thinner in the process, or that it was opening up anyway, or that it was the pre-cat lacquer. But I think the Z-poxy film is helping. It forms a great thin level base which means you need less of the top coat you finish with.

- when I did the Weissenborn-copy withe the Sapele top I didn't want it to look that different from the b/s which would have Z-poxy on. So I posted here and Paul Woolson and John Mayes said they had used it on koa and mahogany tops. So I did. An as I say, if the Z-poxy is killing tone I'll happily live with what this guitar is giving me, Again I think it is helping with the projection and sustain

As I say, early days and I may be fooling myself but I think it is adding it's own Mojo. I have heard of others putting a thin wash on spruce tops to "pop the grain". I'd be more interested to see what is going on structurally and tonally. I used to think that no-finish was best tonally. I don't think so now. I think that a certain finish thickness works with the top wood to improve tone, and then you hit a point where damping kicks in and more is bad. My great friend Peter Cree tells me about how he builds his amazing nitro finishes up bit by bit and how for a day or so after applying, the guitar sulks and sounds crap. Then all of a sudden it roars. After he told me I tested it out and he was right.

Sorry for the long ramble

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

But what constitutes a "thin" coat of the z-poxy (I have not used it yet)? I'm getting a very thin finish french polishing, and my fear is that I'd be doubling the thickness or worse if I were to leave anything but the pores filled.

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I noticed that several of you are using Z-poxy for the sides and something else on the top. Does that mean you would only coat the side of your top binding or do you put the Z-poxy on the top side and purflings.

Thanks

Philip

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If you think my playing is bad you should hear me sing!
Practice breeds confidence and confidence breeds competence. Unfortunately, I'm stuck in practice.

Like Joshua my main concern about Zpoxy (which I'm about to use for the first time) is film thickness; my goal is a finish that is as thin as possible. I have previously used other epoxies and sanded back to bare wood, leaving the epoxy filler only in the pores. It seems to me that a layer of epoxy under the finish is bound to give a thicker total finish film that just nitro.

The other concern is that when I use nitro, sanding through to bare wood as I level the finish seems inevitable; like I said I try to keep the finish as thin as possible, and that usually means sanding through here and there until the very last few coats. If you sand through Zpoxy there will be blotches, as it has some color or hue to it. I don't understand how you can avoid this if you leave it on as a layer.

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Rian Gitar og Mandolin

Joshua and Arnt,

The issue is not about thickness per-se but rather about damping impacts of a finish on wood. The amount of Z-poxy I have to mix to get the layer is also a guide to me. One day I will weigh it. It is not very much all. This resin has good flow-out/self levelling properties and cures very hard.

I thought that as well as the low weight of FP, part of it's tonal plus quality was the hardness that it cures to.

As I said in my post I beleive you have to get to a certain thickness to get best tonal results and after that you start to lose.

I haven't used it on softwood tops and don't really see the need at the moment (would love to do some experiments though if I ever get the time) but I have no resevations at all about using it on hardwood tops.

Joshua - Best thing is try it out on some scraps first. Do the z-poxy plus FP on one part and next to it do your normal fill FP and compare the film thicknesses.

Arnt,

The way I do it is almost 3 stages. First I spend a lot of time preparing the back and sides to get as smooth and level a surface as possible before hand. Then put on the Z-Poxy thinly and spend time levelling this out when it has cured. If you cut through here you just wipe on a diluted with alcohol mix with a paper towel. You now have pore sealed and have the equivalent of your first nitro (or FP) coats. Then I apply my lacquer thinly (usually 4-6 coats) and then level this back. If you cut through the lacquer the Z-poxy layer shows up before you go throgh it - as I say it is a tough coat and you would have to be very unobservant (or unlucky) to keep going through to the wood. If you cut through you just spray on another lacquer coat and continue.

It works for me and I judge with my ears but as Al C always says . . .

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Thanks for the explanation Todd!

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Dave Rector
Rector Guitars

[QUOTE=Arnt] Like Joshua my main concern about Zpoxy (which I'm about to use for the first time) is film thickness; my goal is a finish that is as thin as possible. I have previously used other epoxies and sanded back to bare wood, leaving the epoxy filler only in the pores. It seems to me that a layer of epoxy under the finish is bound to give a thicker total finish film that just nitro.[/QUOTE]

The first coat will probably not be measurable in thickness. It will collect in the pores and "wet" the surface of the wood, especially when using a squeegee. The second coat might build up 1 mil, since it is not penetrating and sitting on the surface of the last coat. Most nitro sprayers try to get somewhere around 4-5 mils on the body and less on the top. When I was spraying nitro, it would take 5 or more wet coats just to start making the pores disappear. That is one of the big drawbacks of nitro and the "piano" finish we are after. Nitro naturally wants to pull away from the pores rather than flow into them. It would seem z-poxy is just the opposite.

[QUOTE=Arnt]The other concern is that when I use nitro, sanding through to bare wood as I level the finish seems inevitable; like I said I try to keep the finish as thin as possible, and that usually means sanding through here and there until the very last few coats. If you sand through Zpoxy there will be blotches, as it has some color or hue to it. I don't understand how you can avoid this if you leave it on as a layer.[/QUOTE]
A valid concern. If you sand through the z-poxy, you will have to spot-seal those areas before applying nitro. It is a better plan to insure you don't sand through. All you have to accomplish with sanding the final coat of z-poxy is to remove ridges, lint, big dust particles, and establish a scratch pattern for the topcoat to adhere to, since we are relying on a mechanical bond. I have found that the green scotch-brite pads do a good job of dulling the surface without the fear of sanding through.
I have not used the z-poxy yet, but intend to use it on the next one. I have done lots of finishing with other compounds that share similar application techniques.

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Thanks for sharing your experiences, guys!

[QUOTE=TRein]
When I was spraying nitro, it would take 5 or more wet coats just to start making the pores disappear.
[/QUOTE]

Was this after a previous pore filling step? Like I said, I like to fill just the pores with epoxy so that everything is nice and level and spray nito over that, no need to make the pores disappear with nitro as they are already gone by the time I start spraying.

OK, I have the Zpoxy, I have the scraps; time to do some testing myself instead of all these questions...

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Rian Gitar og Mandolin

Arnt,
I never used epoxy as a pore filler. I always used oil based paste wood filler, which is far from ideal. The whole epoxy filler thing seemed way too tedious.

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Stay with the happy people.
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I might have over looked it but what type of Z-Poxy are you using? 5 min 30 min. or does it matter?

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Thanks Todd

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Say what you do, Do what you say.

[QUOTE=Dave Rickard] I might have over looked it but what type of Z-Poxy are you using? 5 min 30 min. or does it matter?[/QUOTE]

I just ordered the 30 minute - what's everyone else using?

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Thank You and Best To All

Actually Larry, it's neither the 5min or 30 min, it is called Finishing Resin. I found it here for $14. I ordered a set 3 years ago, and still have 1/2 bottle remaining, and I've finished lots of instruments with it. This is the part # to get: PT-40 Z-Poxy Epoxy Finishing Resin - 12 oz. $17.49 $13.99 You can get it HERE
Good luck!
Tracy

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Tracy
http://www.luthiersuppliers.com

[QUOTE=LuthierSupplier] Actually Larry, it's neither the 5min or 30 min, it is called Finishing Resin. I found it here for $14. I ordered a set 3 years ago, and still have 1/2 bottle remaining, and I've finished lots of instruments with it. This is the part # to get: PT-40 Z-Poxy Epoxy Finishing Resin - 12 oz. $17.49 $13.99 You can get it HERE
Good luck!
Tracy[/QUOTE]

Thanks for the link(s).Not sure where I got the 30 minute in my brain but it's on its way so I'll try it anyway.

Anyone else use the 30 minute and any reason I shouldn't use it?

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One thing I think is happening with Zpoxy as well is that the first coats of nitro actually melt into it - if it can be thinned with denatured alcohol, then lac thinner which is obviously present in lac will do it as well.

the wipe on 3rd coat is max .001 thick - its water thin the way I do it. Its just for an even colour, and it adds a great bonding for the nitro to stick too - its better tan raw wood IMO. I have noticed this difference on tops that got the wipe coat vs those that did not - the finish was harder to chisel off under the FB ext and the bridge.

Arnt - when flat sanding back a zpoxy/nitro finish, until the first 5-6 coats of nitro are on, dont sand back - let it build a bit first - just sanded back two bodies today, virtually flat everywhere, works like a charm. Ready for the final top coats now.

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

[QUOTE=LarryH]
Anyone else use the 30 minute and any reason I shouldn't use it?[/QUOTE]

Larry,

I've used the 30 minute on a couple of guitars. It's thicker so you'll have to work harder to get it scraped off. I used a razor blade, (but round the corners to avoid scratches.)

It was harder to sand, but it filled the pores with fewer coats and I like the color better.

Work quickly because it sets up faster than the resin.

Bruce

[QUOTE=TonyKarol] One thing I think is happening with Zpoxy as well is that the first coats of nitro actually melt into it - if it can be thinned with denatured alcohol, then lac thinner which is obviously present in lac will do it as well.
[/QUOTE]
Not too sure about this assertion, Tony. Once the z-poxy is hardened, it should be insoluable in anything. That is the whole purpose of 2-part systems. Alcohol can dilute liquid epoxies, but will not affect cured epoxy. Lacquer thinner, to the best of my knowledge, will not thin liquid epoxy at all.
It is possible that the z-poxy is not fully cured for a few days. If the surface is open just a bit then the more aggressive solvents in lacquer thinner might be able to key on to the surface.

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Stay with the happy people.
--Reynolds Large

You may be right TRein, but I do notice a difference. Usually I start spraying the day after the wipe on coat is on, and it is given a quick 400 grit scuff. Thats not mcuh mechanical bond, especially since I would never sand bare wood that fine - 250/280 max. its possible the wipe on coat being thinned is not fully cured .. all the better I say as it works great.

I think Doolin used to say that when spraying the first coat of KTM9, he would do this before the epoxy pore fill was fully cured as well ... after a few hours I think.

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