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| Emtech 6000 witness lines, can't get rid of them! http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=22069 |
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| Author: | Parser [ Tue Apr 21, 2009 8:31 pm ] |
| Post subject: | Emtech 6000 witness lines, can't get rid of them! |
Well, I've been working on my first guitar finished with Emtech and am experiencing witness lines. I sanded thru the original finish and attempted to spray some touch-ups. The first go-round of this I cleaned the top but did not rough it up first...when I tried to wet sand this area it starting "balling up" and clogging the paper...basically did not have good adhesion between the base layers and the touch-up layers. First lesson - rough it up with 220-320 before respraying. Then I roughed it up...and this helped out...but I am still getting witness lines. I sanded through the finish once again while attempting to get rid of the witness lines. Second lesson - spray enough finish at first so that you don't run any danger of sanding thru. Third lesson - touch-up quality may be marginal The Emtech looks nice, but I am not convinced that it will not prevent witness lines if you spray coats further apart than a day or so. Please feel free to point me in the right direction if i'm not already heading that way..! At the least, I know that some others are trying to run some guitars with this type of finish and wanted to post these results. Thanks, Trev |
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| Author: | Ken C [ Tue Apr 21, 2009 9:11 pm ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
Parser, I'll be shooting Emtech 6000 within a couple of days for the first time. I'm pretty familiar with Target's USL, which I found a joy to work with. I am expecting the same from the Emtech. My one suggestion is to not wet sand. I always sand dry when leveling interim coats. You will need to use 400 grit between coats. This will still clog, but I found 600 to clog way to easily with a recently sprayed finish. I used to wet sand only after the finish cured for final leveling prior to buffing out, but I have since switched to dry sanding then as well. If the finish has fully cured, it can be dry sanded without clogging even the finer grit papers, and I find I can better see what I am doing using dry paper. Ken |
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| Author: | SniderMike [ Tue Apr 21, 2009 9:40 pm ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
I thought I had a similar issue with USL, the one time I used it. The "witness lines" turned out to not actually be witness lines, but were caused by wet sanding. Totally went away when I switched to dry sanding with Abralon pads. It was probably the hard Denver water I was using (I didn't try filtered or distilled water), but anyway, that's my story. I never had layers of finish ball up or anything like that. |
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| Author: | Bill Hodge [ Tue Apr 21, 2009 9:41 pm ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
Howdy Parser, I don't know how well this applies maybe Ken C knows better. Target says it is not necessary to sand between coats if the wood is properly prepared except in the case of contamination. Below I've attached a PDF file from Target with a schedule and other tech info. In addition, here is a link to their finisher's forum where you can ask the experts or read up on how others dealt with the same or similar problems. http://www.targetcoatings.com/forum/ |
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| Author: | Mark A Thorpe [ Wed Apr 22, 2009 6:28 am ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
I've finished two with EM6000, One I wet sanded to 2400 micro mesh. I could see witness lines when I finished sanding, but the witness lines disapeared when I buffed the guitar, I used Novus #3, and Novus #2 to buff the guitar, I hand buff. On the second guitar I dry sanded with 600 grit then I went straight to Novus #3 then Novus #2. This guitar is 10 times glossier than the one I wet sanded. I learned EM6000 does not like to be wet sanded. when I dry sanded I made sure to keep the sandpaper clean, I would make a couple swipes with the sandpaper then wipe it off with my hand. That worked well for me. I am finishing an electric with it right now. I have sprayed several coats, I've lost count I've sprayed so many, most of these coats have been tinted with waterbase dye. I have sprayed coats more than a couple of days apart, I did a level sand before spraying the next coat. They do melt together because I had a run on the bottom of the guitar and I thied to wipe it off with my finger and it took the lower coats off with it, so I do know that they melt together. |
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| Author: | Ken C [ Wed Apr 22, 2009 7:01 am ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
I found that USL needed leveling after each of the first two or three coats. After that, I could shoot three coats a night with no leveling between coats. I would then level the next day prior to shooting the next three coats. Most of that leveling was just to clean up dust nibs and overspray. With good spray equipment that finish lays on super smooth. On one occasion I had more than a week go by between sprays. I simply hit the surface with dry 400g prior to spraying and had complete burn in--No witness lines. In talking to Jeff Weiss before purchasing the Emtech 6000, he assured me the Emtech would spray and behave just like the USL, but would have more of a nitrocellulose feel when cured. I'll be able to opine on the Emtech 6000 within a few days. Ken |
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| Author: | Mark A Thorpe [ Wed Apr 22, 2009 7:09 am ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
The EM6000 does have a good feel to it. |
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| Author: | Parser [ Fri Apr 24, 2009 11:17 am ] |
| Post subject: | Re: Emtech 6000 witness lines, can't get rid of them! |
Hey guys - just an update. I have since stopped wet sanding at all and am already liking my results better. I have to believe that you guys were right about the wet sanding causing the "witness lines" (which may or may not actually be witness lines!). I do like the final appearance and feel like I'm finally getting over the hump on learning about this finish. I also like the way the finish feels on the neck...definitely not a problem there! Thanks, Trev |
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