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I have to agree with Woody here. Block sanding is adequate with CA. That is why I posted elsewhere that I liked it. Block sanding epoxy is not much fun.

But I would sure like to hear someone answer the "grain popping" question posed above.

John?

Mike

The only reason I can think of why one might be better than the other at "grain popping" would have to do with how the material sands down to wood. Perhaps the epoxy (being not as hard as CA) gets a bit "buffed" with the sanding proscess. If this were trully an issue, mabe sanding the CA and then "buffing" the surface without any buffing matter might be the answer. This all assumes some kind of base sealer like shellac. I have seen CA repairs that were amazing once buffed out.

Mike

having done both ... IMO zpoxy pops better than CA. plus it adds a bit of warmth with its golden hue.

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

So.......could one fill the pores with CA, sand back to where the pores only are filled, then apply a thinned coat of epoxy to pop the grain (and also work as a final fill coat)? I guess I'm asking is CA compatible with epoxy or would this cause a problem?

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Formerly known as Adaboy.......

The fact that zpoxy does indeed have a hue bothers me. Especially since it is supposed to be a pore filler. Thus, if the hue remains, then more than pore filling has occured. With the CA, you quickly get back to wood. And no added color. I think this color thing is what caused me so many headaches with my first use... I did not want the color.

Mike

This is just speculation but I find the concept that epoxy in itself is 'popping' the grain to be somewhat doubtful. Nitro will pop the grain as will just about any clear finish and the greater the 'depth' or thickness of that finish, the more the grain will be enhanced. Evidence of this phenomenon can be seen when viewing an object which is submerged in a pool of water. To a point, as the depth of water is increased so to is the refraction of light causing a displacement of perception and magnification of the object.

I suspect those leaving a wash coat of epoxy on the wood to highlight the grain are in fact only replicating that process in making the 'total' thickness of the clear coating greater than it otherwise would have been and it is the physically greater depth of the 'coating' which is achieving the desired affect and not the epoxy on it's own. If this is so, then depending upon ones own school of thought in regard to the tonal contribution of the back and sides, this 'thicker' clear coat may not necessarily be a desirable thing.

I know some people sand the epoxy back to bare wood when filling the pores and others do not. As I see it, if you are of the former then the difference between filling pores with CA or epoxy in terms of grain enhancement should remain undetectable. On the other hand if you are of the later school, it is MHO that filling with CA and then applying extra coats of clear finish to compensate for that depth normally obtained with epoxy should over come any grain enhancement concerns you may have.

As I said, this is my own speculation. But it seems to make a lot more sense to me to accept that a 'physical' effect is at play here rather than a chemical one. If this is indeed so, then it should follow that 'any' coating of comparable clarity and thickness should have the same 'visual' effect on wood grain, regardless of it's chemical make up.

Cheers

Kim

I agree. There is no doubt that zpoxy for example, adds a hue to the wood if a thin layer remains. If one sands back to wood, that hue dissapears. If hue is wanted, I would add that to the finish material. I have found that zpoxy is very difficult to sand back to wood. I have to be too agressive and I do not like that. CA is remarkably easier to sand back. I have wondered about this. Perhaps CA is "harder" than zpoxy. Sanding something that won't shear easily might be the issue. Maybe at test board setup is in order. I am thinking using a thickness sander might be the ticket. I think I will order some 320 paper for the sander. Hard wood and soft wood blanks less than half the width of the sander, one side of sander for the CA and one side for the zpoxy.

Thoughts?

Mike

Kim and Mike, I definitely have to disagree. Take a piece of wood, mahogany for instance, and wipe some epoxy on it. Squeegee every last bit of it off the surface, but make sure it "wets" the wood. Now spray another piece of mahogany with as much clear lacquer as you want, and it will never look like the epoxied piece. Do it with waterbased lacquer, and it will look even more boring. Why does the epoxy pop the grain more? I really don't know. I just know it does. So does oil, and shellac does a really good job too, although not quite as much as epoxy, IMO.

At least that's my experience, for whatever it's worth.

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Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

I'm going to repeat something I've read here on this sight.......can't say for sure it's fact but it makes sense to me and maybe it explains the epoxy "pop".

What makes the grain of the wood "pop" is when the index of refraction is similar to the index of refraction of the wood. The refraction index isn't the same for epoxy, laquer, shellac etc. so they won't give wood the same look. My understanding is that epoxy and some of the oil base finishes and some varnishes have an index of refraction closer to wood and the grain looks pronounced......or "pops" more. I'm not sure this affect changes with the depth of the finish.

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Formerly known as Adaboy.......

16 oz of starbond for $32

Brudduh, he we go again. And yes, I recieved the link regaring the index of refraction of wood. But it did not help me understand. So therefore, until I can find some sound scientific literature on this subject, my mind remains open but extremely skeptical.

Anything wetting the surface of the wood will make the grain pop. But if you sand it back to wood, no pop. And no more pop than had you done the same thing with epoxy, CA, shellac,... However, if you leave a little epoxy layer behind, then the pop is still there. Ad what I am saying is I do not like the color it adds. Well, its OK, but I would rather not have a basecoat determine that. Shellac already adds a little, even blonde.

Rather, I am up for a test on this. Sadly, I have no suitable scraps. So if you want me to do the test, I would be glad to. Mail me some suitable scraps of hardwood and soft wood.

BTW, I am sure "pure" cellulose has an index of refraction.

Mike

System One epoxy doesn't color the wood like z-poxy does. I don't believe West Systems does either. I don't use epoxy, but I used System one on one guitar.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Mike,

What about when both pieces have then been rubbed out, buffed and are completely finished? Both pieces with an equal total thickness of clear, allowed to harden and then completely buffed out is the only real way to compare.

I read somewhere that parchment paper is infused with silicone. I also read that silicone can cause havoc with finishes. I'd guess that whatever's in the paper is mostly inert and stays there, but it might be something to keep in mind.

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Mike Lindstrom

I've used parchment paper wrap when bending sides on about 30 guitars with a variety of finishes (waterbourne, nitro, catalyzed urethane). No problems so far.

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Jimmy Caldwell
http://www.caldwellguitars.com

Kim, I finished some koa three times, the first two not being satisfied at all with the way the flame came out. The third time I grabbed the Z-Poxy from my shelf (sanded all the way back, Mike), and the grain went insane.

James,

You've not seen the grain go insane on a guitar finished only with nitro? I have seen plenty, and the depth of grain can normally be attributed too a good depth to the finish. But if epoxy does have some property which makes it superior to other mediums for grain enhancement, what is the scientific reasoning behind this?

To that point the term 'Index of Refraction' has been used as a possible reason to explain this allegedly superior grain enhancement ability and whilst it 'is' true to say that different mediums display variations in this index I remain sceptical. Surely if there was merit to the argument that index refraction were the main contributing factor, it would have been openly exploited by the industry which markets this stuff. I am too right brained to be much good at physics and this may explain why I find nothing readily available to me which clearly demonstrated the index of refraction is at play.

From what I understand, refraction is caused when a wave, in this instance light, is 'slowed down' by a given medium as it passes through. Therefore, for the purpose of this conversation, it is a mediums ability, or lack there of, to slow down light which give us it's measure of indexation. Can anyone point me to data which demonstrates the difference in the index of refraction between epoxy and nito? More to the point, what affect if any does this difference make to how wood is viewed through a coating only a few microns thick?

I concede that the index of refraction may well turn out to give us a definitive answer of what is actually happening here. But without some facts, it remain no more feasible than my own speculation. As for Jame's point that he applied epoxy and then "sanded all the way back and the grain went insane" well this seems to take the index of refraction argument completely out of the picture.

Cheers

Kim

Kim,

James can clarify but I thought he meant he sanded all the way back to wood (leaving no previous finish in place) then applied the z-poxy which really popped the grain figure. If I understood correctly, then he is saying that z-poxy had a better affect than the other finish/sealer/filler he applied.

It does seem to me that oil finishes give the wood a better look......or pop the grain more.......than say polyurethane. So it seems to me there are differences.

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Formerly known as Adaboy.......

I absolutely cannot give you scientific proof . . . LOL, I'm a humanities guy through and through. What I can tell you is the Nitro looked dull, I stripped it off, applied Z-poxy, sanded back to the wood, and the figure went insane.

I use Z-poxy because I prefer it, but I hope you guys understand that I'm not interested in trying to prove anything.

Ditto that (although I prefer West Systems lately). There's no question in my mind that epoxy pops the grain better than just nitro. I don't even care why!

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Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

Maybe it has to do with porosity in the finish. An evaporative finish like nitro may have tiny pores left behind, as the solvent gasses off, throughout the thickness of the finish (invisible to the eye), whereas the reactive curing of the epoxy is more "solid". Perhaps the porosity of the evaporative finish makes the reflecting light more diffuse, thus less crisp, than through the epoxy.

Indeed Jason, hence my reasoning to suggest that there is no point in making any comparison about which mediums enhances the grain best until all samples have been completely finished, buffed out and polished. I suspect the results would be that given equal thickness there really is very little difference at all.

Back to the main point of this thread, I shall certainly be testing out the CA grain fill thanks John.

Cheers

Kim

Oh yeah, I almost forgot about that. I'm going to give it a go too. (and wipe some epoxy on top of it!)

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Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

Make sure you give it all a good spray with nitro after that Mike, a good buff and polish and she'll come up so schweet no one will ever know.

Cheers

Kim