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I'm in the drying/curing stages now after brushing this on. I used Z-poxy for pore filler followed by 2 coats USH3000 UltraSeal-WB Shellac. I used the EMTECH SA5 Retarder with EM6000 brushed on, 3 coats. Everything was brushed on. It flattens out pretty good when dry even though there were a lot of brush marks and bubbles. We'll see what happens in a week when I sand and buff.

If this works, I'll never change. It was so relaxing to brush it in my basement. Nothing in the air to worry about. And, unlike the time I tried spraying it, I didn't get any craters.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Hutch--

There is a lot to like about brushing on the finish. The price you pay, however, is in the increased amount of level sanding that will be necessary to get it as smooth as what comes off the spray gun. Maybe I just stink at brushing, but for me, brushing = lots of level sanding.

Very interesting, can't wait to hear how it turns out.
Are you intending to do multiple sessions of 3 coats brushed on/ then level sand?

I have been spraying EM6000 for a decade now, and need 3 sessions of 5-6 coats each session....

It smooths out pretty well as it dries using the linker/reducer. I also think it goes on a little thicker with a brush so 3 coats may be enough with careful sanding and razor removal of any runs. Worse case, I have to add more coats, this stuff claims 100% burn in so it's repairable and recoating later on shouldn't be a problem. We shall see.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Do they claim 100% burn in even with addition of the cross-linker? Straight EM6000 burns in beautifully in my experience.

I'll be interested to see if 3 coats will be sufficient. I used EM6000 as a brush-on finish with retarder and without cross-linker for several years and I had to do many more coats than that to get sufficient build. It went on very thin, typically with a wet film thickness of less than 1 mil. If I brushed on heavy, I could get it up to 2 mils but risked runs. Maybe the cross-linker thickens the EM6000 so it builds faster.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I'm going away for 4 days so I will have to hope that it's enough or the burn in is true even with the crosslinker. I never gave a thought to the crosslinker taking away the best part of this finish.

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Hutch

Get the heck off the couch and go build a guitar!!!!

After a time and reconsidering, I'm going to apply more coats to be safe. I just mixed up a new batch and I hope the crosslinker doesn't inhibit the burn in qualities.

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Hutch

Get the heck off the couch and go build a guitar!!!!

I just left a comment on Targetcoatings website to see if the crosslinker impedes the burn in.

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Hutch

Get the heck off the couch and go build a guitar!!!!

I wanted to love water based finishes but I could never get it right and I brushed it on too. I admit though that it's been over ten years now since I tried them so there is probably better stuff on the market. I think it was called KTM, then I tried the Stewmac stuff (at that time) which I liked a lot better. They had a cross linker too and my understanding of it was that the linker made it a catalyzed finish which means you lose the burn in property. The trade off though is that you get a more protective finish.

I tried doing a google search for this and there is nothing I can find out there. Target really should have this in their FAQ.

I look forward to seeing your results. I'd really love to find a good water based finish but after my bad experiences I'm always hesitant to try.

If that's the case, I probably should go with my first idea and carefully level my 3 coats or at least scuff sand these coats before applying more. After spraying a bunch of lacquer, I really enjoy the peace and calmness of brushing this on. It looks really good after 3 coats which is why I though I could carefully level and buff it. I wish I had measured the top before I started so I could have an idea of how thick the 3 coats are. Maybe I'll remember this next time.

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Hutch

Get the heck off the couch and go build a guitar!!!!

This is very close to my experience with early water born finishes. I tried whatever StewMac was selling 12 or 14 years ago, it had a bluish tint and I got witness lines when I sanded thru layers. I then went to KTM-9 because some folks I admire were using it - same issue with witness lines. I went back to lacquer and have had absolutely no problems since.

I know lots of people like the Target finishes but I've been burned twice and don't feel like gambling again.

I love lacquer too. I just don't have a safe place to do it accept outside and I've sprayed in the winter outside with no issues. My problem is gassing off. I can't bring it into the house because my wife is sensitive to the smell. I don't think it's good idea to leave it outside in the winter so that leaves me with spraying in warm weather and leaving it outside in a tent or something.

EM6000 went on beautiful with a brush and the sanding is not a big deal for me.

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Hutch

Get the heck off the couch and go build a guitar!!!!

This type of experience from ten or more years ago with water based finishes seems fairly common. I've seen comments like this come up in forums quite a few times and KTM finish is a common element very often cited as a problematic finish. It's a shame that it put people off from trying other water based finishes. I used EM6000 from 2012 up to a year and a half ago and then switched to Endurovar. I've been very happy with the results with both as brush-on finishes. I know other builders who have also gotten excellent results with both of these finishes.

I like brushing the finish on a lot. For one thing, I need a grand total of one tool to do it. One brush. That's it. No spray rig. No compressor. No spray booth and everything that goes with that. No respirator. And the end results are quite good. I've had a couple professional builders look at my guitars and think the finish was nitro, so it is possible to make these finishes work well.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

That's good to hear Jay. I should probably get some and do some test panels. Yes it was the bluish finish and the fact that if you made a mistake and sanded through it was impossible to fix.

It's been at least 7 days since I put the last coat on. I decide it would be best to add more from our discussion here. After wiping it down with alcohol, the finish got sticky. I'm pretty sure the burn in is going to happen. I plan on 2 more coats for a total of 6. Is that enough?

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Hutch

Get the heck off the couch and go build a guitar!!!!

I haven't used the crosslinker with EM6000 so I can't say if 6 coats will be enough to avoid sand through. This also depends a lot on how well the wood surface has been leveled. I've only used EM6000 with retarder and that goes on very thin so it takes a lot of coats to get enough thickness that sand through is unlikely. I don't know if cross linker would improve that or not.

Do you have a wet mil gauge so you could measure how thick the individual coats go on?

You could consider putting 6 coats on a test piece of wood prepped the the same way you did the wood on your guitar and then sand it and see how it goes.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I’ve been using EM6000 and its predecessors for what seems like a couple of decades. I’ve tried many different methods and devices both powered and un for level sanding. What I have learned to avoid burnthrough is to use a two inch long crepe rubber eraser as a sanding block wrapped in 320 (3m yellow) sanding paper for intermediate sanding (between coats and P800 for final level sanding before polishing (working up with polishing compounds). Trying to do too much at a time led to burn through on areas where I wasn’t paying attention. Slow and steady does it. And, even a couple of inches at a time, it usually only takes me an hour or so to level sand the whole instrument.

In over a hundred guitars with EM6000, I’ve never achieved one that looks like nitro, but they usually look pretty good. I’ve never used the cross-linker. Burn in usually works pretty well even several years after the original work.

I generally spray a total of 10 to 12 coats in two or three days, stopping after half of the coats to level with 320 as described above. After the cure time (7 to 10 days), I do the final level sand with the P800. Sometimes in winter, I’ll brush an instrument. (I prefer to spray outside rather than setup my indoor spray booth). I’ve found that brushing works best for me with a very good sable brush and very thin coats— no going back, one good thin stroke and move on. With the thin coats, it takes as many as with spraying. I do stop to level more often with the brushed coats. My experience with brushing thicker coats was that it was hard to get it leveled.

Aside from a few runs, it seems pretty flat after about an hour of curing. I don't know if it's because of the crosslinker. I plan on going at it more aggressive than you with my ROS starting at 320 grit. If I sand through, I'll add some more coats and follow your plan. I know I should bow to your experience now but I just can't help but try it my way first. It's just my nature, I hate following rules until I get bit.

Can you show some photos of you finished guitars? You've done a hundred of them so you must like it.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Here’s one photo. You can find many others on my website (url should be obvious). All are finished with EM6000 but #135 (EM7000–I didn’t like it) and the classicals which are french polished.

I recall a long time ago trying to level sand with an ROS...didn't work for me as it was way too aggressive, even with the finest grits.
As with Bob, I find with a large eraser using p320 or p400 I can level sand between coats pretty quickly; I have not sanded through in a long, long time...
I wait 2 weeks before final sanding with p800 then hit it with the buffer.

FWIW I always dry sand with EM6000 - wet sanding is a recipe for disaster...

This is an interesting discussion. I've only used lacquer and shellac, but I've read about oil finishes and these finishes, and may try something along those lines. Jay, if you care to share, I am curious why you went to Endurovar? Also are you currently using Endurovar II?

Endurovar, and Royalac are on my radar as well.

I started scraping back the finish with a razor blade with tape on the ends. I feel like sanding might take off the finish in the low spots prematurely. I think this might work but I really need to let it set a while longer before going full bore. I stayed away from the edges as best as I could. Of course I won't be able to use this technique on the neck.

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Hutch

Get the heck off the couch and go build a guitar!!!!

I switched to Endurovar in part because another builder I know switched from EM6000 to Endurovar and was getting great results, but I switched mainly because the total time it takes to apply it by brushing it on is much shorter than with EM6000. I found I had to use the retarder with EM6000 for it to brush on well. With EM6000 + retarder, the coats went on very thin (only about 1 wet mil) and the shortest interval between coats I used was 2.5 hours because of how long it took for the previous coat to not be tacky. The thin coats plus the long intervals between coats and the number of coats to get enough of a build to avoid sand through added up to 6 days.

The schedule I use to brush on Endurovar is based of Woodie G's Endurovar schedule (thanks Woodie G). The intervals between coats are only 1 hour, probably because retarder isn't required. In addition, the coats go on thicker and Endurovar has a higher solids content than EM6000. All those factors combined mean I can apply the finish in 2 days instead of 6. That's a big plus.

The one concern that I have is that I haven't yet had the opportunity to repair sand through or other damage to Endurovar so I don't know if it has the great burn in quality of EM6000.

I haven't tried Endurovar II. When they announced that change in formulation earlier this year, I found and bought some of the last remaining original Endurovar to hold me over until the new formulation has proven itself.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Even with the reducer, the brush marks were pretty deep. I started sanding with 320 in my ROS, knowing that I'll probably sand through in spots. I got it all level again and tried another approach. My cousin had just given me an airbrush system so I gave it a try. I don't think I'll ever use a full size spray gun and compressor again. This was so quiet, which is one of my main goals in building. Yeah it takes a few more strokes but it's still better than brushing and almost as good as a spray gun.



One thing I noticed, I should have used the shellac first as there are still some color differences where I sanded through. I'm not going to worry about it and move on. It's all I can do not to throw it in a fire and move on with my second.

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Hutch

Get the heck off the couch and go build a guitar!!!!

If you sand through on spruce it will always show as a color difference. Spruce starts changing color right after it is fresh sanded. Fresh sanding takes it back.

I mostly spray so I am not an expert at brushing, but when I was "Brushing" on varnish I would not think of the brush as a brush but has an applicator to feed the varnish to the wood. Think of the brush as not touching the wood, rather allow it to glide on a smooth film of finish. It requires a good brush like a Taklon. I brushed on water based Spar varnish. To avoid witness lines, one could not sand through the last coat.

One last thought, I have found through experience that sand throughs are less about the application of the finish, and more about sanding prep. I am not good with sanding prep. Now I will not apply a top coat until I can level a shellac seal coat without sand through or gaps. I basically start applying top coats on an instrument that looks finished. Others looking at a dry instrument in a variety of light angles can see what I miss.

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