'Z' Poxy

[joolstacho]

I'd be very dubious about thinning epoxy resins to get better penetration into the grain. Typically you'll get 35% decrease in strength if you add even as little as 5% thinners. Epoxy chemistry is pretty critical, and not designed for thinning. If I use epoxy I want to get the absolute max hardness to preserve tone... I don't want anything soft or rubbery in there, and that's effectively what you get if you go mucking around adding thinners. It won't catalyse thoroughly.
If you want a less viscous fluid, try 2k Automotive Clear. I use it as a grain filler. (Unthinned) - It's already thin enough to soak right into the grain, and it cures hard and crisp cooked at around 35 -38 degrees for a few hours.
2 brushed coats, sand with 320 -400, a spray coat, sand 400 then 600 and she's ready for final spray clearcoat.

West systems hardeners, -you'll find the fast hardeners are more yellowish, and the slow ones are almost clear.
Zpoxy is not usually used for laminating because it doesn't really have the hardness required, they advertise 'flexibility' on the pack.

Store epoxies in cool conditions.

Good info at:
http://www.seqair.com/skunkworks/Glues/ ... nning.html

[Kim]

Just another point.

Before anyone decides to use epoxy to fill grain prior to applying any finish, they should take the time to understand "epoxy amine blush". More to the point, they should be clear on the relationship between amine cured epoxies (which is all of them) and the temperature, Co2 and H2o that are present in the air during mixing, application, and curing....could go a long way to helping you understand what Trevor is suggesting can happen a few years down the track..prevention is the best cure.

Here's a start for ya...enjoy : http://www.google.com.au/search?source= ... gle+Search

Cheers

Kim

[kiwigeo]

I'd be very dubious about thinning epoxy resins to get better penetration into the grain. Typically you'll get 35% decrease in strength if you add even as little as 5% thinners.

Is strength that critical when you're using epoxy as a filler rather than an adhesive?

[jeffhigh]

If you are applying a thin coat of epoxy with added thinners, they will have flashed off within a minute leaving only the undiluted epoxy in the pores and on the surface.
Sure if you leave diluted epoxy in the mixing cup to cure, it will be affected badly, but applied to a surface is another matter.

[greg]

At a microscopic level, solvents that flash off leave pinholes in cured resins. Even though there are 'solvented' systems to thin epoxy, there is another class of 'reactive diluents' used to lower viscosity that do not flash off like solvents but rather cure along with the resin. Whether you realize the same Barcole hardness, I don't know, I am not sure it would matter for the purpose of pore filling.

I am very new here and have been lurking for a while just to pick up as much info as I can about making a guitar before I get going. As an ex long time boat builder though, I am intrigued by the practice of pore filling using epoxy resins the same as or similar to what I have used to build boats on and off for nearly 30 years now. The thing about West System and various other brands produced for the same industry is that they are not UV stable. If you leave an unprotected resin filmed substrate in direct sunlight it will break down, as in disintegrate. The way to stop this breakdown is to coat it with a pigmented paint or a clear with UV protection. Now the thing about clear UV protection regardless of brand is that it will stop the breakdown but it will NOT stop the yellowing of the cured resin.

This leads me to my intrigue about using these resins to pore fill. In order to pore fill you guys must be using a squeegee to spread the resin and to push it into holes/pores so as to not leave a resin film that pools on the surface of the guitar body (excess sanding). You will be pushing it into crevices and larger pores making sure to scrap off the excess resin. During this process you end up 'wetting' the entire substrate. This wetting is a result of the resin soaking into the outer fibers of the wood. Penetration is based on how porous the wood is, viscosity and temperature. You then have to go through a process of sanding the surface to key it for the next layer (whatever that is) and to smooth the raised fibers... My question is, do you sand the substrate back to bare wood ie, so that it leaves larger pores filled but exposes virgin wood again, or do you simply sand it smooth and fair leaving it with the changed 'wetted' albeit matt finished appearance and then re coat from there?

[kiwigeo]

My question is, do you sand the substrate back to bare wood ie, so that it leaves larger pores filled but exposes virgin wood again, or do you simply sand it smooth and fair leaving it with the changed 'wetted' albeit matt finished appearance and then re coat from there?

People go for both options here. I generally sand back so only pores have resin in them and the wood matrix is bare.

[Dominic]

Hey, i heard back from the ecoepoxy guys that Dennis mentioned and they will ship overseas. Prices seem a bit cheaper then West Systems so I think I will get some and report back.
cheers
Dom

[joolstacho]

Martin, it's not so much that it's not as strong, more about WHY it's not as strong. Has it cured to a really 'crisp' state or is the chemical process compromised so that it's a bit on the soft side? - I've seen mouldings that are like this, and if you tap them they're absolutely dead, whereas a properly cured, correctly mixed one will ring like a git!
-Jools

[kiwigeo]

Martin, it's not so much that it's not as strong, more about WHY it's not as strong. Has it cured to a really 'crisp' state or is the chemical process compromised so that it's a bit on the soft side? - I've seen mouldings that are like this, and if you tap them they're absolutely dead, whereas a properly cured, correctly mixed one will ring like a git!
-Jools

I've got three guitars which Ive pore filled with Z poxy. I cut the Zpoxy with IMS grade meths for last 2 of three pore filling sessions and haven't had any problems....the diluted Zpoxy coats cured rock hard.

[voitty]

Just wondering if I can stain the timber after doing the pore filling with z-poxy or do I stain first?

[MBP]

I have found penetrating epoxy or thinned epoxy doesnt penetrate anymore than normal epoxy unless the wood is rotten.

Surfboard epoxy would probably be best for gap filling wood as its clear, has decent UV resistance and if you have a board maker locally they would sell you enough to do a few guitars real cheap. Or you could get it from Shapers.

Waterbased lacquer can be a great gap filler for woods like blackwood if theres no big knots etc.

Timbermate works well on NGR.

[Clancy]

I generally sand back so only pores have resin in them and the wood matrix is bare.

But if you then put a wash coat of thinned epoxy on to even up the colour (as per Allen's tutorial), your back to it being fully covered with epoxy (extremely thin, but still there).

BTW, the new Gore/Gilet Build book advices sanding flat, but not through, the brushed on epoxy coat.

[kiwigeo]

I generally sand back so only pores have resin in them and the wood matrix is bare.

But if you then put a wash coat of thinned epoxy on to even up the colour (as per Allen's tutorial), your back to it being fully covered with epoxy (extremely thin, but still there).

BTW, the new Gore/Gilet Build book advices sanding flat, but not through, the brushed on epoxy coat.

I generally put on one coat of neat Z poxy and then a couple of coats of thinned Z poxy. I sand back between coats. I don't leave a thin coat of Z poxy over the entire surface....my approach is to fill the pores only not end up with a Z poxy undercoat.

[Trevor Gore]

Does anyone know for sure that Zpoxy doesn't bloom down the track? I've never used it, so don't have a packet/instructions to read. It may be on the pack or you may need to contact the manufacturer. So many people seem to be using it and I'd hate to see a whole generation of white guitars in a few years.

[Clancy]

I first started using Z-poxy after reading about it in Graham McDonald's Bouzouki Book (sorry graham, not trying to put you in the 'hot spot' )
The book was first published 2004, so I assume he had been using it for a while before that.
He would have made a fair few instruments in that time and, by experience, might be able to comment better than anyone else I know on any time delay defects in the product.

For what it's worth, here's the box. (The leaflet might explain the 'strange red colour')

ZP1.jpg (133.48 KiB) Viewed 15663 times

ZP2.jpg (115.55 KiB) Viewed 15663 times

[Kim]

Zpoxy has been used for at least 5 years that I am aware of and there are a few reports now starting to appear of 'belated' adhesion issues. Not too sure about this being related to the "bloom" or whitening that you mention Trevor as the instances appear to be more consistent with the affect of "amine blush" and I am led to believe blush and bloom are two different things..

My understanding of chemistry is quite limited and I can only glean what I can from the work of others, but as I understand zpoxy hardener is formulated from 'crude amines'. This is why the product dries so hard and is very easy to scrape and sand. Unfortunately this also means that zpoxy is more prone than more refined products to forming amine salts or ammonium carbonate on the surface of the curing epoxy which can then go on to develop into cyclic urea among other compounds. These contaminates in themselves or combined can cause all kinds of issues from adhesion problems for lacquers and can actually 'reverse' the polymerisation process responsible for hardening oil based finishes such as varnishes and oils etc. so they become soft and tacky after a while.

This 'blush' of amines can present itself in a number of ways that are dependant upon the ambiance or more accurately, temperature + moisture + ppm of C02 at the time of mixing, application and curing. So depending upon that combination, ammonium carbonate can form as crystals, as easy to see white 'waxy' deposits, or as a water thin oily substance that can be very difficult to detect unless you really look closely.

Now because its essentially a salt, if detected ammonium carbonate can be removed from the surface of cured epoxy with plain water and a scouring pad. You do 'not' want to try sanding it off as this will only server to work the substance into the surface causing more issues. If you wish to be more thorough that a plain water wash you can apparently add vinegar or citric acid to the water which will allegedly ionise free amines into salts thereby increasing their solubility...Be that as it may, I have weighted evidence that washing will 'not' completely resolve the blush problem. I think when given the right combination of temp+H2o+Co2, ammonium carbonates forms 'within' the curing epoxy and not just upon the surface. So whilst you can wash away the surface contaminants, you can't do anything about those which has formed 'in' the curing epoxy.

The issue here is that the ammonium carbonates which become suspended in the cured epoxy will still eventually make their way to the surface over time because epoxy never fully cures. When they do, they will probably cause issues with any finish sitting on top of the epoxy and that can present itself as a blueish or milky look to lacquer that will then develop into air pockets, blistering and peeling as the finish looses adhesion, or as mention, a tacky feel to any polymerised oil based finish.

So how do you avoid the problem? Well you could reduce the risk by using specially formulated 'low blush' formulations of epoxy but the problem with them is that they are not well suited to the task. The amines are more refined with additives such as 'nonyl phenol' which can reduce blushing significantly. But, the MOE of the epoxy is altered and it becomes softer and far more resistant to abrasion. Now this would be great if you are using the product on a boat deck but its the last thing you need when you need to sand the shit off again.

The only real sure fire answer is to avoid epoxy under a finish. The next best thing is to understand what is going on to cause the blush so you can prevent it occurring in the first place. Therefore the number one thing to minimise during mixing, application and curing of epoxy is exposure to Co2 and considering that you will be breathing out shitloads of the stuff all over the project as you work, it just makes good sense have a fan running between you and the epoxy as you work, and if you can, do it all outside to keep the ppm of Co2 to an absolute minimum..the big bonus here is that you will minimise the exposure of your skin to the toxic epoxy fumes and believe me, even if there were no such thing as amine blush, running a fan is worth doing just for that benefit alone. You may have never had a sensitivity issue with epoxy in your life, but take it from me, that can change at any time your immune system decides it should when it sends in the "T" cells to rip your body apart to dispose of the invader...if that battle happens to take place in your lungs, your fucked.

Cheers

Kim

[Trevor Gore]

Thanks for the input, gents.

So far, I've not had any adhesion issues, just "bloom" when I once used WEST with 206 hardener. A discussion with WEST and a change to 207 hardener fixed things. WEST pretty well guarantee that the coating will stay clear if 207 is used (and that's been my experience), but suggest that you do yourself some favours by mixing/applying/curing in low humidity. There don't appear to be any significant strength issues in coatings that have bloomed.

I had a similar conversation with a tech guy from Gurit (who took over the SP resins business). Gurit have a special coatings hardener that basically does the same as WEST's 207, but I've stuck with WEST and I can't recall the Gurit product codes. The Gurit guy also pretty much guaranteed the product, but also suggested mixing/applying/curing in low humidity. The "bloom" is a reaction to high humidity down the track, according to both WEST and Gurit.

The "bloom" as I see it is different from amine blush, which seems to be a waxy deposit on the newly cured surface. This always gets removed in my finishing schedule because I wash it then wet sand with soap and water. The 206 will bloom even though the "amine blush" is as comprehensively removed as it's ever likely to be. The bloom is in the epoxy, not the finish that's applied over.

Hence my reticence to use any epoxy as a clear coat/grain filler that doesn't come with a similar "guarantee". BTW, 206 doesn't always result in blooming, but why risk it?