Official Luthiers Forum!

Seems like alot of folks really like the system 3, and I am leaning towards it (as I am leaning towards KTM-9) for this first acoustic build.

However, I am not sure I am comfortable with how finicky it is supposed to be with getting the exact ratio in the mix, and don't really want to invest in fine scales for this occasional usage.

What are your opinions on either product, anything compelling to recommend one over the other? Experiences? Can I just use the regular pore filler compound from StewMac (which i have a ton of) with the KTM-9?

adam

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"Everyone wants to BE something, but nobody wants to BECOME something" - William Cumpiano

Have only used the zpoxy and it seems very non problematic as far as mixing goes.Have had some problems with it used under polymerized tung oil on necks.Don't think it's a zpoxy problem as much as it is a problem of it being used with the oil finish.Plan to change finish on necks in the future.

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A person who has never made a mistake has never made anything!!!

never used sys3 .. but Zpoxy couldnt be much easier, or tolerable of an approx mix. Its a dream to use IMO.

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

You can use the Stew-Mac pore filler you have with KTM9. It will probably take a few more coats than epoxy but it will work. I'd recommend a couple coats of shellac between the filler and the final finish to make sure everything bonds. I've only used Z-poxy once, and I've never used System 3, so I can't make a comparison there.

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

I used to use System 3 and found out the hard way that it is really picky about the mix ratio. It works great if you carefully measure by weight to get the proper ratio, but you'll need a scale that's accurate to a tenth of a gram. I just went back to my can of McFadden's filler. Very dependable. No mixing. Fills the pores.

I also neglected to mention that I went back to nitro, too, after a not-so-pleasing KTM-9 experience.

Do tell!!

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"Everyone wants to BE something, but nobody wants to BECOME something" - William Cumpiano

I've used Zpoxy and have since switched to System Three.

The mixing ratio is not a big deal. I use a small beaker about the size of a shot glass. If you don't have one just put some masking tape on a regular shot glass and mark at something like 1 tablespoon and 2 tablespoons. (It is a 1:2 mixing ratio by volume & , 1:.44 by weight). I have even done very small batches by doing 5 drops of one and 10 of the other. I have never had a hardening problem.

I pick it over Zpoxy for four reasons.

1. No amine blush with System 3. (that is the oily feel you get with zpoxy after it dries. It has to be completly removed before more expoxy or finish can be put over it)

2. Since there is no amine blush you can recoat it as soon as it is dry to the touch. (no sanding required unless it has gone to full cure in around 36-72 hours, depending on the temperature) I like to use a rubber squeege and put on as thin of a coat as I can. The next morning I squeege on another coat. The day after that I level sand. If all is well, wait another day and then preceed with finish.

3. It is clearer than Zpoxy. I like that on the head stock. Lets the inlays show truer.

4. System 3 Clear Coat is thinner than Zpoxy so it pads on quite well.


I don't use epoxy on the top unless it is curly redwood or I want a darker look. When I do use it on the top I just pad it on with a pad made from an old t-shirt. Keep it thin as possible

NEVER THIN EPOXY !!! Big trouble ahead if you do.

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Joe Beaver
Maker of Sawdust

Starting to think maybe i will just continue with the Colortone Waterbase Grain Filler I have already.

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"Everyone wants to BE something, but nobody wants to BECOME something" - William Cumpiano

I hear you on that but....... I'm convinced that an epoxy filler gives a much better base for KTM. It has little if any shrinking and the filler doesn't settle into the wood over time.

Only problem I've had is when I used thinned Zpoxy on a neck then used Tru Oil. Not a good idea. Don't know if it was the thinned epoxy, or the resultant amine blush or just the action of oil on zpoxy that was to blame.

One thing I'm going to start doing though, is use a good shellac (Wax free) over the System 3 then the KTM 9.

Joe

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Joe Beaver
Maker of Sawdust

I use the System III epoxy and the mixing ratio is really not that hard to get right. I use little plastic epoxy mixing cups I bought at the local hobby shop. They hold a couple of ounces and are graduated in milliliters and ounces. A package of 50 cost a couple of bucks.

I have used epoxy thinned with DA after pores have been filled to even out the color before I start applying the lacquer. I haven't had any trouble thinning it like Joe says. I also recently finished my second guitar with Tru-Oil / System 3. So far no issues.

My only experience with the water based filler was helping a friend finish a koa guitar. It was really messy stuff to work with, but the end result looked great. I think any finish you choose is going to have pluses and minuses.

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53% of all statistics are made up on the spot
http://driftwoodguitars.blogspot.com/

I've been planning on Zpoxy. I am about to close up my first box!:) Local price is $14.50. Good price? Is there a Luthier supply to get it from?

One note on sanding System Three. It is hard to sand once it has gone to full cure. I try to sand it 12-18 hors after applying. All you need is dry to the touch and it wet sands just fine.

Once you let it cure and start applying finish it is less likely that you will sand through the epoxy when you level sand the finish. I like that.

Joe

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Joe Beaver
Maker of Sawdust

I've used System 3 then KTM 9 with very good results. My experiences were as follows:

Got the mix ratio close enough so that the hardening time was reasonable (e.g. within 24 hours it was plenty hard and dry to the touch).

The challenge I had was to apply the right thickness of epoxy to the back and sides - went on too thick the first time - and the sanding took forever. After I got it right, it was fine.

I like KTM 9 - I've sprayed it a couple of times with good results, as long as you get enough of a build. Previously I've viewed it as much safer than Nitro but have come to understand (from some very knowledgeable builders) that it's got some health hazards of it's own - so definitely use a ventilator, vent the spray, and use safety gear if you're spraying.

Some have talked about the bluish tint of KTM 9 - I've never experienced it. I love the quality of the finish once it's buffed out.

I've tried both. Sys III isn't that hard to mix right. I just use little mixing cups from Lee Valley and that seems to work fine.

The Z isn't as 'clear' as the System III, which is to say that it isn't as water white but seems to have a yellowish tinge to it. Not that this probably matters much once in a pore...

I didn't notive much difference while sanding as I usually wait a long time before doing so.

System III is more expensive than the Z.

So if I had to choose between the two, I'd go with pumice stone every time!

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I'd like to be able to prove, just for once, that money wouldn't make me happy...

I pore fill with Devcon 5-minute epoxy. It take about 10 minutes to fill the back and sides. Wait about 20 minutes and sand. Repeat if pores need more filling. You should be able to complete your pore fill in under an hour. I wait 24 hours before applying the finish. I've used this method for at least 60 guitars and it works great.

I've also been a system three epoxy user for the past 15 years. I use it for my bracing, fingerboards, bridges, necks, lining, laminates, rosettes, etc. If you use the pumps you spend less time fussing with measuring or weighing it. I use about 4 gallons a year! To extend the cure I fill a bowl with water and a mixing cup and put it in the freezer. When this is frozen I now fill the cup with my epoxy and mix it. I don't use system three for pore fill. For pore fill I'll use CA glue or the cheap devcon 5 minute epoxy. I like the LMI oil based filler for my necks, but sometimes I'll use that on the bodies too.

David,

It is very nice that you have joined us. It is always great when a true professional comes along.

About the gluing with System 3, which product do you use?

Thanks,
Joe

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Joe Beaver
Maker of Sawdust

Hi Joe,
I use the System Three Epoxy Resin and Hardener

I use the three different hardeners depending upon the situation. Most of the time I use the medium hardener.

David,

Good deal. I might give it a try. I do like system 3

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Joe Beaver
Maker of Sawdust