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| Question on Z-poxy. http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=29212 |
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| Author: | Stuart Gort [ Fri Sep 24, 2010 1:03 pm ] |
| Post subject: | Question on Z-poxy. |
They make 5-minute, 30 minute, and "finishing" resin. I'm assuming you folks are using the finishing resin for pore filling. Yeah? Nay? |
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| Author: | Pat Foster [ Fri Sep 24, 2010 1:11 pm ] |
| Post subject: | Re: Question on Z-poxy. |
yeah! Pat |
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| Author: | Dave Rickard [ Fri Sep 24, 2010 1:34 pm ] |
| Post subject: | Re: Question on Z-poxy. |
YEP |
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| Author: | Stuart Gort [ Fri Sep 24, 2010 2:21 pm ] |
| Post subject: | Re: Question on Z-poxy. |
Thanks guys, Hey Pat. I appreciate the comments on the guitar....and I'll bring it to the next meeting. See you later! |
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| Author: | Stuart Gort [ Fri Sep 24, 2010 2:28 pm ] |
| Post subject: | Re: Question on Z-poxy. |
Question 2. I've seen a thread or two about applying a wash coat of epoxy thinned with denatured alcohol in order to take care of sandthough issues. I thinned a few of the epoxies I have here and the result was to chemically alter the epoxy....and it never cured....which I expected, having needed to thin epoxies in a former life. It could be that the threads I remember were refering to another formulation of epoxy other than Z-poxy. Will Z-poxy finishing resin come to a full cure, having thinned it 50% with denatured alcohol and applied as a wash coat? |
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| Author: | Pat Foster [ Fri Sep 24, 2010 3:14 pm ] |
| Post subject: | Re: Question on Z-poxy. |
Stuart, I had some curing issues with my first French polished shellac over Z-poxy on a keeper guitar. It's been 5 years, and it still has issues where the pores of the koa and mahogany have these tiny bumps. I have sanded them smooth and hit them with shellac, only to have them show up again months later. This was the only one where I'd used z-poxy thinned with alcohol and the only one where I had the problem. Later builds I only used straight Z-poxy under shellac and haven't had a problem yet. So, I don't know for sure if it was the alcohol, but I won't risk it happening again. Many here have had no problem, but I don't know how many of them had shellac over Z-poxy. Pat |
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| Author: | ChuckG [ Fri Sep 24, 2010 4:12 pm ] |
| Post subject: | Re: Question on Z-poxy. |
I have heard numerous times that you should not sand back to the wood when filling with Zpoxy, but my opinion is that I just want the pores filled and nothing else. I have always sanded through to the wood - very carefully mind you - and I've never had any problems with new pores popping up. I always do 2 applications of filler and sand each back before proceeding. My 2 cents worth... Chuck |
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| Author: | Josh H [ Fri Sep 24, 2010 4:12 pm ] |
| Post subject: | Re: Question on Z-poxy. |
For filling I do 2 coats of Z-poxy with a little silica thickener added. Sand down high spots with 220 after the epoxy has cured over night (I use the 3M Gold finishing paper). Finally I wipe on 1 coat of Z-poxy thinned approximately 50% with denatured alcohol. I have found this last coat is usually dry to the touch in a couple hours and I have never had a problem with it curing. Once the thinned coat is dry I lightly go over the guitar with 400 (again 3M Gold), just in case there are any little nubs, dust or fuzzies. Then it is off to the spray booth, Nitro in my case. Josh |
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| Author: | Josh H [ Fri Sep 24, 2010 4:15 pm ] |
| Post subject: | Re: Question on Z-poxy. |
Maybe I wasn't clear but the reason I do the thinned wipe on coat is to make sure the colour is even. I have tried sanding the epoxy back so that it is only in the pores, but that is tricky (like Churck said). You run the risk of opening up new pores. Provided you do a good job of applying the epoxy there should be very little left on the surface of the wood. Josh |
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| Author: | KiwiCraig [ Fri Sep 24, 2010 7:34 pm ] |
| Post subject: | Re: Question on Z-poxy. |
There is a waxy type residue ( amine blush ) which rises to the surface of the Z-poxy upon curing . This cannot be removed by solvents and sanding the epoxy only spreads this amine blush over the surface. Water and a mild detergent with a scotchbrite pad is the only answer in removing this residue. You do run the risk of leaving a water stain in the wood . It seems not all finishing material is affected by this amine blush. I haven't read of any folks using Nitro having a problem. Z-poxy under tru-oil has been reported a number of times to be problematic . Tiny bumps appear which give the finish a rough feel .This may take some time ,in some cases months . Pat foster says in his above post that he has had these problems with shellac over Z-poxy , but used a 50/50 Z-poxy final coating which may or may not have caused his problem.I've used Z-poxy ( not a 50/50 mix ! )under shellac and not had a problem ( SO far ! ) |
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| Author: | BobK [ Fri Sep 24, 2010 8:51 pm ] |
| Post subject: | Re: Question on Z-poxy. |
I've used z-poxy on something like 10 builds. I've finished with both lacquer and tru oil and have only had problems with the blush that Craig mentioned on one guitar neck. A coat of shellac before the first top coat has been suggested as a preventative for the problem. One problem that doesn't have an easy fix is that zpoxy shrinks. My last build was a walnut body finished with tru oil and pores started to show 30-40 days after the last coat of oil. In earlier builds I attempted more of an open pore look so I never really noticed the change, but this build was smooth as glass after the last coat of oil. Bob |
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| Author: | TonyKarol [ Sat Sep 25, 2010 9:27 am ] |
| Post subject: | Re: Question on Z-poxy. |
I find the trick when sanding the 2nd std coat Zpoxy back is to not have any sections that sand and still have a white hazy appearance - if a section has that, then its still too thick, and after the thinned coat, and under finsih, it will be a darker blotch ... there is a point at which the zpozy still just darkens the wood, but has no real film depth to it, and thats what I shoot for - you can still go past this point, and hit bare wood with filler in the pores, and the thinned coat will still even it all out. I just did this to 3 bodies yesterday, and they are all looking just fine. |
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| Author: | Fred Tellier [ Sat Sep 25, 2010 9:39 am ] |
| Post subject: | Re: Question on Z-poxy. |
Quote: just use a heavy duty window squeegee to get off all but the thinnest coat I finally got a handle on Z-poxy use on the 3rd guitar I used it on and now after 2 more I am real comfortable with the process and results. It finally sunk in I was leaving too much epoxy on with each coat, watch the videos Todd has posted real close and note how little epoxy he starts spreading and still gets coverage. Fred |
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| Author: | Darryl Young [ Sat Sep 25, 2010 9:48 am ] |
| Post subject: | Re: Question on Z-poxy. |
What grit paper do you use to sand down the zpoxy? Do you use 3M 216U or similar paper? I'm leaning toward using zpoxy and have been debating if I need a shellac seal coat between the zpoxy and KTM-SV finish. Like the poster above, I've wondered if zpoxy would leave an amine blush after curing and if it should be dealt with before topping with anything. Since this is my first time finishing I will work first on a test panel so I had thought about using shellac on half the panel before finishing the entire panel with KTM-SV. I'm not sure the best way to test adhesion of one vs the other so I had thought of gluing a piece of wood to each finished surface with CA. Maybe I could use a lever with weights to determine if one holds better than the other. This assumes that if there is an adhesion problem, the finish will break loose from the surface below before the CA lets go from the finish. Is there a better way to test? Maybe I should try removing the amine blush on half of the panel to see if it makes a difference. Then there would be 4 sectons to test. First time I've heard that epoxy thinned in alcohol may not cure properly. I've thinned epoxy with alcohol many times to "paint" a firewall on an RC airplane so it wouldn't absorb fuel. It always cured fine. Stuart, you said you suspected there may be a curing problem. Can you elaborate? |
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| Author: | Fred Tellier [ Sat Sep 25, 2010 10:29 am ] |
| Post subject: | Re: Question on Z-poxy. |
The abranet screen type disks on a RO with a vac attachment have worked well for me 400 grit or even 320 at 1st. I will try the Joest brand disks I recently picked up on the next one. Fred |
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| Author: | ChuckG [ Sat Sep 25, 2010 12:07 pm ] |
| Post subject: | Re: Question on Z-poxy. |
I use P220 grit Norton after the first application and P320 Norton after the 2nd. I look for a surface that has no slick dark spots or hazy spots (I think Tony and I are looking for the same thing) and again, I sand very carefully to avoid opening up new pores. It takes me about an hour to sand a guitar body. After finishing, I may have a couple of drop fills to do, but The color is always nice and even - no blotches. For application I get one of those window squeegees and cut it into four or five small ones. After using that, I go back over the surface with a single edge razor blade and that leaves a very thin coat. You have to work fast to do this, but it makes the sanding much easier. Chuck |
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| Author: | Pat Foster [ Sat Sep 25, 2010 12:18 pm ] |
| Post subject: | Re: Question on Z-poxy. |
I believe splotches may have to do with how well the clarity and color match the top coat material. The wetting characteristics, color and clarity of Z-poxy make it seem to be compatible with shellac and varnish, both also know for clarity, and I've had no splotchiness using those topcoats. Pat |
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| Author: | Pat Foster [ Sun Sep 26, 2010 4:47 pm ] |
| Post subject: | Re: Question on Z-poxy. |
Filippo Morelli wrote: Pat, with sand through and re-coat, I've been able to see the splotchiness prior to finish being applied. Filippo Filippo, Hmmm.. I see the splotchiness on sand through areas prior to the finish being applied too, though without a recoat, but so far it has disappeared over mahogany, EIR and BRW, with Behlen's Rockhard Tabletop Varnish or FP shellac. I wonder if it could be an issue with fresh epoxy not wetting the cured epoxy? I dunno. Pat |
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| Author: | Stuart Gort [ Mon Sep 27, 2010 12:09 am ] |
| Post subject: | Re: Question on Z-poxy. |
Appreciate the responses, guys. I'm pore filling on a very contoured electric body surface. Any tricks on that? I've made a number of test specimens with a similar complex surface just to try to get the hang of it before I commit to doing the guitar. I have a good handle on the squeegee technique for flat surfaces but there aren't very many of those on this guitar. So far the best technique has been to slather it on with a gloved finger and try to apply it as evenly and thinly as possible....then sand evenly using a pliable, yet firm foam block. Lotta hand work on this...which is fine but if there's a technique I might try that saves time...my fingers will thank you. |
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| Author: | Fred Tellier [ Mon Sep 27, 2010 7:45 am ] |
| Post subject: | Re: Question on Z-poxy. |
The gloved finger is how a lot of people do necks, just be sure to not over do the amount of epoxy you start with. A little goes a long way and makes the leveling easier. Fred |
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