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I am considering using Z-poxy for the first time to fill the pores (rosewood) and have been trying it out on scrap. I found it easier to apply it with a razor blade (a little bit dulled, with "safe" corners) instead of a credit card. I'm not getting any ridges. So, applying it has been no problem. It took two applications to fill the pores.

My question is: After you fill the pores, what grit sandpaper do you use to level it down? And, do you level it just like you do when you're rubbing out a finish (that is, so that it's all dull all over, no shiny spots — and not sanding all the way down to bare wood)?

I'm getting a bit confused because I've read that some people say sand down to the bare wood, some people say don't do that. And, if I level it so it's dull, do I still wipe on a 50/50 thinned coat of the Z-poxy (which I assume you don't sand at all), to make sure it's all even?

Thanks for any advice you can give me!!!

Kathy

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Kathy Matsushita
San Jose, CA USA
http://theamateurluthier.com
Facebook: https://www.facebook.com/kathy.matsushita

Kathy...you've just basically described the 2 schools of thought regarding Zpoxy application. I sand back after a day or so with 220 grit to where it is just dull...not to bare wood. I then apply a base coat of 1# shellac and it is pretty much ready for any finish. Others who sand all the way back to wood only leave the pores filled.

The worst thing that one could do is to have patches sanded to wood and others that are epoxy coated. This difference could very well show up in the finish.

Good luck and let us know what works best for you.

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

Kathy,

First I agree on the razor thing but both get the job done.

There are two main schools of thought both sand to wood and leave only in the pores then mix a thin batch to just color the wood. this is my preferred when I use Zpoxy. Sand back with 220p

Then there is the other school of leveling the film I think most are using 220,320 and 400p as final grit.

I have done both work fine no issue either way other than I find leveling the film to require several spot repairs due to sand through.

I believe it was Howard Keepler that recommended using a cabinet scraper to remove excess hardened film and I have done that once.

My past history has taught me it takes typically 2 sessions to completely fill the pores on medium pores and sometime 4 on very open pores.

I like this pore filling system but have recently changed to Starbond Medium thick CA. Following pretty much the same process. Of course this requires the use of a respirator and gogels.

Thanks, JJ! I just now sanded it with some 400 grit (the gold one), and it seems to sand nicely! It's dulled (like when I rub down a finish). But there are still tiny shiny spots (I imagine, the pores). Do I keep sanding till even all those tiny spots are dulled? Or is that what it's supposed to look like? If I leave those tiny shiny spots, does the 50/50 thinned epoxy take care of everything?

Am I assuming rightly that it's only when you sand down to bare wood occasionally but have other larger areas with epoxy still on it, that you get that blotching in the finish?

Kathy

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Kathy Matsushita
San Jose, CA USA
http://theamateurluthier.com
Facebook: https://www.facebook.com/kathy.matsushita

Kathy,

I have used Z-Poxy on my last three this way:

Apply first coat with Bondo spreader (Any auto parts store) , wait 24hrs, scuff down any ridges with 400 grit, appy second coat, wait 24hrs, again scuff down any ridges or bumps. (Just make sure when you are finishing each filling sessions to get all the resin you can off with the scraper.)

It usually looks slightly patchy so I too mix up a 50/50 mix of Z-Poxy and methylated alcohol and wipe on with a piece of clean old T-shirt.

This is just what I do and it almost looks like it's been fully finished after the washcoat.

Ray

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Guitar Building = Continuous Improvement Process

Another thank you for your great website.

I just did my first z-poxy fill on padouk. Huge pores, took several passes, but man that wood came alive. I think it had such a cool effect on the look that I didn't want to sand all the way back. I mixed some 50/50 with alcohol and covered the few spots where I did go through, but I don't think I'd want to do the whole guitar this way.

Where as the batches I had mixed full strength dried hard (the leftovers in the cup), the 50/50 seemed to stay rubbery. Perhaps it would harden eventually, but I wouldn't trust it.

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Gabriel Regalbuto
Carlsbad, California
Freedom 35!

I sand back to wood to make sure I don't get into trouble if I sand through when leveling in subsequent finishing stages. I don't dilute the Zpoxy at all, I think it has an excellent viscosity for pore filling straight out of the bottles. The cured filler sands fine with 120 grit (STOP once you see any wood dust along with the epoxy dust), I then use 220 before shooing the first coats of nitro. Two coats of Zpoxy is usually sufficient to fill EIR.

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Rian Gitar og Mandolin

I'm in the "it's a pore filler, not a finish" school. I sand back to wood just leaving the Z-poxy in the pores (Pore filling, the clues in the name!). But if you really want to leave a coating on the wood - I'd want to come back in 50 years and see how it looks then - after sanding back just use the 50/50 mix and apply with a pad.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

just so may not mistake the porpose of the 50/50 mix (I use 40/60 epoxy/alcohol) is to color the wood after the pore fill is sanded back not to fill the pores. that is done with a 1/1 ratio of hardner to to base.

One more note: I have found that if I mix and batch over the top of a dead pot life batch there seems to be some reaction that inhibits the cure of the new batch. I always mix any new batch in a clean new mixing cup. Mixing batch on top of batch is the only time Zpoxy has given me a cure problem. In my 40/60 mix I mix the epoxy first then quickly cut it with alcohol 60% by volume. this is near water thin and is raged on not skimmed or squeegeed. The intent is to wet the wood with an even but very light coat for color only. I have never had Zpoxy not cure it is very forgiving on ratio as compaired to other rinishing resins.

I do the same as Collin and am happy with the results.

Cheers Martin

I sand back to the wood with 220. Scrape if there are thick spots, but I usually can avoid thick spots. If you scrape, you need to get a fine, even edge on the scraper or you will end up either with scratches you didn't see until the finish gets buffed, or with sanding back to coarser grits. Like Colin, I'm suspicious of epoxy as a sealer coat, and more practically, I put on too thin a coat not to sand through a lot of spots when I level. Sure it looks good when the gloss appears, but so does the first coat of finish.

I don't use Z-poxy. I'm sure it's a fine product, but since I get good results with 5 minute Devcon from the hardware store, I haven't seen any reason to change. Dull razor blade with safe corners, and really get rid of all the excess when squeegeeing. I like typing squeegeeing, so there it is again.

I've found that it's OK to see a bit of gloss left in the pores, except when it's not. I.e., they could be just below the wood surface where the finish will fill, or they could be further down.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

I've just put some z-poxy on a orphaned rosewood back which I made a mess of to see how it would go.
I notice that it has changed the colour of the maple back strip.
When doing this for real, should I mask the bindings (maple)? If so does this mean also masking the back strip?
What about the front? I've read not to z-poxy the front, but what about the top of the binding?
I'm really confused!!!!
The back/ sides are imbuya and the top is sitka. Maple binding and back strip.
My first guitar used plastic bindng, so I just scraped off the filler (colortone).
Sorry to sound so pathetic, but I really don't want to risk ruining what is so far a really nice looking guitar.
Thanks for any advice,
Charles.

Epoxy finishing resins will pop the figure, if any, and darken the color nicely of maple bindings. I personally like the look and besides you are likely to use something else as a seal coat like shellac on the entire guitar and that will darken things somewhat too.

So I would not mask the bindings or back strip and instead use the epoxy on everything but the top. You can, if you wish, even use a mixture of 50% epoxy and 50% denatured alcohol and wipe the top too. The 50/50 mixture is wiped on after filling the pores on the rest of the guitar if you want to leave a thin film of epoxy on the guitar to pop the color and the mixture, once applied, evens everything out including where you may have sanded through.

As you may have read above some use epoxy as only a pore filler and some will exploit the wetting properties of epoxy to pop the color and figure of the wood.

I would also like to thank Kathy for her great website, and for answering a few of my questions.

I received a box of Z-poxy from LMI today. I also have maple on my walnut/spruce guitar, a curly maple end graft and peghead.

Hesh, Thanks for answering Charles question about masking maple when applying Z-Poxy, you gave me the answers to a couple of question that I had. It's good to know that I don't have to mask it off.

Can someone tell me how much Z-Poxy should be mixed for each pore filling session?
Also, once mixed, how long does it take before its unusable? Thanks.

Ron M.

One oz will do a back and more if squeegeed in and excess scraped off and worked quickly. In about 15min it starts to thicken slowly I don't like to use it once the viscosity starts changing because it is a tad harder to work into the pores while keeping the film thickness at minimum.

Thanks Michael. Time to test it on some scrap wood.

Ron M.

Okay...so I'm back now. Sorry I haven't replied for such a long time to this thread I started, but I've been pretty busy trying to finish up my guitar (school is fast approaching -- yikes!). I finished the building yesterday, so today I have begun the finishing stage.

I first did all the sanding, then, this afternoon, started applying the Z-poxy. I found using a dulled razor blade (safe corners) is working the best for me, to avoid ridges and get rid of the excess. I found applying it to the curved areas (neck, sides) was easiest with a piece of t-shirt wrapped around my finger. So far, I've done one coat and will do the next coat tomorrow, after lightly sanding it with 400-grit. I'm thinking it will take at least two coats to fill the pores.

I'm liking the process, how easy it is to apply, and how nice it's making the wood look. I'm thinking I'll just level-sand it, instead of sanding all the way back to the wood, and see how that goes. Hopefully, I'm doing this right! It's a whole new process for me.....

(If you want to see how my guitar is looking, I've been chronicling it daily on my site --- here's today's posting: http://home.comcast.net/~kathymatsushita/moreprojects/htmlpages/atc31.html)

A BIG THANKS TO ALL THOSE WHO GAVE TIPS/IDEAS IN RESPONSE TO MY POST!!! (I'm a little less confused now.)

Kathy

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Kathy Matsushita
San Jose, CA USA
http://theamateurluthier.com
Facebook: https://www.facebook.com/kathy.matsushita

Looks great, Kathy. One comment...I never apply shellac first but instead apply Z-Poxy to bare wood. Some have reported that ZPoxy doesn't adhere well to Shellac but that Shellac adheres well to Zpoxy...go figure! I have not confirmed this myself and am skeptical. Nevertheless...the shellac has not seemed necessary IMO.

Looking forward to seeing your finished product!

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

I didn't apply shellac to the rosewood. I only applied shellac to the top (which I am not putting epoxy on, of course), to protect it and to serve as its seal coat. (I did take heed of all those posts which warned against putting epoxy over shellac!)

Thanks for the heads up, though!

Kathy

P.S. I just fixed my website page, as I can see now how it wasn't made clear there!

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Kathy Matsushita
San Jose, CA USA
http://theamateurluthier.com
Facebook: https://www.facebook.com/kathy.matsushita

I can confirm this. I z-poxied an IRW classical back and then after a few bodying sessions with shellac found that there were still a few unfilled pores in places. I went in with more z poxy and it definitely didn't like going over the shellac. I ended up replacing the back on the instrument. Same problem happened on a later instrument and I went in with some pumice and managed to get the pores filled up.

Cheers Martin

Hi Kathy,
When you filled the sides, where did you stop? Did you run the epoxy over the top binding.
On my ealier post on your thread this was really the point of my question.
If epoxy is stopped at the top of the side, then will the edge of the binding near the soundboard not be a different colour to the sides of the binding?
If epoxy is lapped over the top of the binding, does it not get onto the soundboard?
Sorry if this doesn't make sense?
Love your site. Really useful when I first made a guitar.
Thanks,
Charles.

I just did the epoxying on the sides — I didn't run it over to the top. On the top I had put a couple of coats of Zinsser's Seal Coat shellac, which also has an amber tint to it, so the color of the koa binding I have is the same under both the shellac and the Z-poxy.

Another thing I just tried today....(I'm doing the second coat of Z-poxy today)...I used one of those makeup wedges that I read about somewhere here (I can't seem to find the post anymore!) to apply the Z-poxy to the sides and the neck. It worked well to apply it smoothly. I suppose I could have used it on the back, too, but I found using a dulled razor blade works well for me there. The makeup wedge does start to crumble in the middle a tiny bit (I'm not sure why), so you have to be careful not to press too hard and to keep moving on to clean sections of the wedge, but I like how easy it made applying the Z-poxy on the curved areas (which the razor blade is not so good at).

Tomorrow I'll see if I need another coat on the body (the neck looks as if it's done)....

Kathy

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Kathy Matsushita
San Jose, CA USA
http://theamateurluthier.com
Facebook: https://www.facebook.com/kathy.matsushita

Kathy, thanks for sharing your experience with Z-Poxy, I just finished applying my first coat.

I have a question for anyone out there. Is there a particular kind of sandpaper that is preferred for sanding back the Z-Poxy, such as wet & dry, free cut, etc...? Thanks.

Ron M.

Thanks again Todd.

Ron M.