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I am just about to start pore filling with system 3 epoxy (SB-112). Is it OK to use system 3 on the top also?

Just for information I am Pore filling with System 3 and will be using KTM 9 Gloss for the finish. I havent decided if I will be using a brush or spraying with a Preval Spayer.

You don't need to porefill your top if it is spruce, cedar, redwood or cypress...

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Francis Richer, Montréal
Les Guitares F&M Guitars

Actually, its a good idea and here's why:

KTM-9, like all waterborne finishes sits on top of the substrate more than it is built up in it. Solvent systems -- lacquers, conversion varnishes, polys, soak into the wood and case harden it as it cures. Waterbornes don't do that. A scratch coat of epoxy will harden the fibers, pop the figure, and fill any voids in your bindings and the like, and it won't add anything to the film thickness of your finish, as long as you simply wet the fibers and don't build the epoxy.

Hardening those softwood fibers will help protect the top.

I was hoping it would be alright to use the system 3 on the top because I have a walnut rosette and there are some small gaps in the binding at the waist.

Hardening those softwood fibers might change the wood properties a lot, and I guess not in the good way.

This may be a good idea for an electric guitar, but not for an steel string or classical guitar. You want to keep the wood intact. Simple coat of shellac will make it right.

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Francis Richer, Montréal
Les Guitares F&M Guitars

Well, you're in luck James. David gave you some very compelling reasons to go ahead and use the epoxy on your top. If you haven't done so yet, go to the tutorial section of the forum and check out Todd Stock's video series on pore filling with epoxy. His techniques will help you achieve a nice thin application.

Todd,

I watched your videos on using zpoxy last night. They were very helpful. Is the application procedure the same for systm three? and if I decide to try to just seal the rosette and bindings around the top what will happen if I get some resin on the top wood?

I've done it before, with z-poxy, and can attest to the depth wicking. Took me a long time to sand it off... Did not like the color effect. Then I was advised it was not needed since spruce has no pores. But I also did one with clear epoxy and got the hardness I was looking for. My last one I used nothing and wished I had. (for the hardness).

Mike

I would be worried about what epoxy would do to the tone. I can't speak from experience as you all can but I just can't imagine smearing plastic all over my carefully braced and thicknessed top. I've always been guided to apply the minimal amount of finish to the top to just barely give it enough protection and to bring out it's beauty. I don't mean to sound pretensions, as from what I have seen in this forum you all do far greater work then I do, but still I just have to wonder about such a technique as related to tone.

Filippo, did you go straight up with the redwood or did you laminate with spruce or some other? Sounds like you used it on it's own. I only ask as I have a top that I'm looking to use on a current build. Looks good with none of the micro-cracking that I've read about recently on other threads. I'd prefer not to laminate and may try the zpoxy thing on this top.

I've use zpoxy on my rosettes to get a good porefill on porous wood, but i don't put it on the whole top. I also sand back to the wood after porfilling and have no problem with uneven shades on the top around the rosette from the zpoxy. System three might be different though as i don't use that because it's not as clear as zpoxy.

Folks, Doolin and Greven have been undercoating their waterbores with epoxy for a long time. If you think Greven's guitars suffer because of the epoxy, might I suggest an audiologist.

All of this concern about damping, etc, makes little sense to me (regarding the epoxy). Can't be more than a few grams spread out over the entire surface (wet), then sanded back some. What interests me the most is the potential for surface hardening, just enough to protect somewhat against dings. Does anybody have access to a Rockwell hardness machine? I would love to see if epoxy does indeed make the surface tougher.

Mike

Why would a thin film of epoxy be any worse for tone than a layer of lacquer/poly/shellac/whatever?

And OP, not to your original question I know, but may I suggest you take your KTM-9 out behind the shed and shoot it. That stuff is absolute crap, having a strong tendency to bubble and blister anywhere skin touches it after a few months. Not caustic sweat either, just normal people's sweat. It shouldn't be sold to guitarmakers. Spare yourself the pain, even if it's already bought and paid for. It's not only me who has had this very negative experience.
That being said, KTM-SV, by Grafted Coatings as well, is excellent. I have a few personal guitars finished with it that are problem free after several years...

As part of my finishing routine for the past 3-4 years. I always mix a very thin batch of System 3 (thinned with denatured alcohol) and apply it with a cloth or fold up piece of paper towel as just a wash coat on the whole top. This seals the wood without adding any thickness to the final finish. I have never had any problems with this approach.

Mark - when you say S3 is not as clear as Z-Poxy, are you referring to the amber tint, or something else? S3 is much clearer that Z-Poxy in the sense that it has virtual no amber to it at all, whereas the Z-Poxy has a very noticeable amber tint to it, so I'm a little puzzled by your comment.

Hahahaha true, who ever thought spreading bug poop on anything was a good idea?

Take a thin sheet of paper, and coat each one in epoxy, lacquer, shellac. That shoud answer the question.

Mike

I 've heard that system3 had an amber tint to it so i have never used it. The zpoxy i've used is totally clear.

Another option for pore filling rosettes is to apply CA after a thin coat of finish. I use Bob Smith Industries Gold medium viscosity odorless CA. It will stick just fine to sanded waterborne, but you can't do the same with epoxy. I let it cure for a few days before leveling and continuing with my finish, though I don't usually use a waterborne. I don't have a problem with contaminating the top with my pore fill with this method.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Thanks Filippo. I'll be doing it without laminating as well. I just recall Harry Fleischman's article in GAL where he let the beauty of the curly redwood blind him and ended up having to retop his harp guitar. I've always had a bit of a devil may care attitude. the guitar is for me, so I'm not worried. Anyway, verging on derailing this thread from the OP question.

[quote="Todd Stock"]Sure you are using the finishing resin? Z-Poxy Finishing Resin has a hardener that (like West 205 & 206) darkens over time from medium amber to dark amber...the lightest I've ever seen is a very fresh batch that was still medium amber.



The System 3 standard resins and T-88 both have straw colored hardeners that darken to a deep amber over time - especially if stored in metal containers. System 3 Clearcoat finishing resin is essentially crystal clear (although very, very picky about mixing) - it's a good filler. Finally, West has 207 hardener that is supposed to be clear, but still darkens to a straw or amber pretty quickly.





I like the slight amber color of Z-poxy on most woods - it warms up rock maple enough to avoid having to put some color in the toner, and adds a lot of depth to ash, oak, Yes, I don't use system three a don't know anything about it. I just know i don't have any problem with the amber color on a top next to the rosette when i pore fill with it.

Thank you to everyone who reply'd. I think I will try to avoid using the epoxy on the top as much as possible. If I do, I will try to thin it down with alcohol like was suggested.

Thanks again
-James

And consider using a clear epoxy for that.

Mike

How do you all apply it? With a stiff card or such a thing? Wipe across or with the grain?