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| Finish problems? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=30515 |
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| Author: | J Hewitt [ Wed Dec 29, 2010 6:10 pm ] |
| Post subject: | Finish problems? |
I started spraying two guitars today. I just opened a brand new can of EM6000. Heres what I did in prep work. Filled the pores with Z poxy. Level sanded between sessions. Sprayed two coats of Zinnser Sealcoat....brand new can of it..... Sanded it with 220 norton paper just to knock the dibbs off. Heres my problem....After the first coat was sprayed...about an hour later I went to spray another coat and it looked like it was cold checked.....lots of small cracks all over everything that I had srayed. I have sprayed several guitars over the last year or so using the same method I described above but I've never had this happen... What is the problem here? Thanks, Jeff |
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| Author: | Bill Higgs [ Wed Dec 29, 2010 6:18 pm ] |
| Post subject: | Re: Finish problems? |
Jeff, I just had the same thing happen to me using StewMac's waterbased finish (slight modification of Target's waterbased laquer) under a 2# cut of freshly made shellac from LMI. Did not happen on previous build where no shellac was used. There is something going on here that nobody seems to be able to put their finger on. I'll bet you have adhesion problems too if you check it out. Wish I could help you. Maybe someone knows something about this and will respond. |
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| Author: | J Hewitt [ Wed Dec 29, 2010 6:33 pm ] |
| Post subject: | Re: Finish problems? |
I tried getting a hold of Jeff Weiss at Target Coatings and as of yet.....have'nt got a response! It's really disappointing that this has happened! Bill, what did you do? Sand it all down and start over? |
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| Author: | Ken C [ Wed Dec 29, 2010 7:53 pm ] |
| Post subject: | Re: Finish problems? |
Jeff, I haven't sprayed over Zinser Sealcoat. Is that shellac? If so, is it dewaxed? Jeff is usually pretty quick at responding if he is around. I don't know what the correct answer is. Did you sand the seal coat prior to spraying the EM6000? I might try sanding down the top coats to remove the cracks with 320 or 400g paper and try shooting again. Maybe just dust the first coat on then follow up with a heavier 2nd coat. If you can wait for a response from Jeff, that is probably your best bet. Finishing gremlins are amazingly frustrating! Let us know what you figure out. Ken |
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| Author: | weslewis [ Wed Dec 29, 2010 8:06 pm ] |
| Post subject: | Re: Finish problems? |
I have srpayed em 6000 over zinsser 100% wax free shellac with no problems... |
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| Author: | J Hewitt [ Wed Dec 29, 2010 9:37 pm ] |
| Post subject: | Re: Finish problems? |
I did spray a second coat an hour after the first coat thinking it might cover up and burn into the first coat, but it didn't. I did notice that the tape covering up the sound hole has the same cracks...there is no shellac sprayed on the tape......so that tells me that it has to be the lacquer itself! Also....did some test spraying on some mdf....just straight lacquer.....got the same results! |
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| Author: | Ken C [ Wed Dec 29, 2010 10:08 pm ] |
| Post subject: | Re: Finish problems? |
How old is the lacquer, Jeff? I have quit buying it when it is on sale. Rather I wait until just before I spray to purchase only what I will need for that project. I don't believe this stuff has a very long shelf life. Definitely an issue you need to talk with Jeff about. Hopefully he gets back to you soon. Ken |
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| Author: | J Hewitt [ Wed Dec 29, 2010 11:45 pm ] |
| Post subject: | Re: Finish problems? |
Ken C.....Its a new gallon I just ordered. |
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| Author: | runamuck [ Wed Dec 29, 2010 11:54 pm ] |
| Post subject: | Re: Finish problems? |
Have you sprayed silicone or another similar contaminant near the area where you finish? |
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| Author: | J Hewitt [ Wed Dec 29, 2010 11:59 pm ] |
| Post subject: | Re: Finish problems? |
Runamuck....no I haven't. I'm thinking that this batch of top coat I recieved is bad! |
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| Author: | woody b [ Thu Dec 30, 2010 7:21 am ] |
| Post subject: | Re: Finish problems? |
It sounds to me like there's some kind of contamination causing your problems, either on the surface, in your gun, in your air supply, or in the finish itself. |
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| Author: | Bill Higgs [ Thu Dec 30, 2010 3:46 pm ] |
| Post subject: | Re: Finish problems? |
Jeff, I would have been better off if I had sanded completly down to the wood. I did not. I just sanded until I thought I could not see the crazing anymore. Bottom line ---- I still have areas of crazing that become obvious in certain light. It has been very frustrating. I'm beginning to think like you, that the batch of waterbase has something altered in it. Hopefully Jeff or Bob V can give some insight. |
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| Author: | J Hewitt [ Thu Dec 30, 2010 6:50 pm ] |
| Post subject: | Re: Finish problems? |
Hi Bill, I talked to Jeff Weiss this morning. He told me he had never heard of this happening, but told me to add some retarder to the lacquer. He also told me to sand it all down but not go down to to wood. Its somewhat hard to sand all that mess out without, either going to bare wood or leaving some kind of trace of the cracked up mess. Anyway.....the retarder seems to have helped. I sprayed several coats today and they all looked good so far.....problem is that ,like you say....there is still that "crazed" appearance even after sanding it down. I'm hoping that the first four to six coats will eventually fill up all those messed up areas from the previous mess. It has been a real pisser! I think I'm going to look for another finish for future guitars. Thanks for everyones input! Jeff |
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| Author: | Bill Higgs [ Thu Dec 30, 2010 11:07 pm ] |
| Post subject: | Re: Finish problems? |
Jeff, I feel your pain. I think Jeff and Bob V are great people trying to do a good job. However, they need to check into this. There is something going on here. Don't give up on the waterbased stuff. The guitar I finished before this was great. I think it is a quality control issue that needs some detective work on their part. |
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| Author: | J Hewitt [ Thu Dec 30, 2010 11:36 pm ] |
| Post subject: | Re: Finish problems? |
Bill, I have used this finish on the last six guitars I have built and followed the same technics that I have done on these two here. I never had to use the retarder previously. Its made more work for nothing...plus the aggrevation of trying to figure out what the cause of the problem was! Plus sanding two guitars and two necks down...that will probally just end up looking cruddy in the end! I have kept up with my hours on build time....90 on one and 60 on the other....and to get to this point and have to fool with the aggrevation of this product! The finish seems to be unpredictable?...or atleast the way I'm seeing things!..?? You know the frustrations! Thanks, Jeff |
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| Author: | Bill Higgs [ Fri Dec 31, 2010 5:12 pm ] |
| Post subject: | Re: Finish problems? |
Jeff, This crazing happened to me on a batch of four tenor ukuleles. I'm scared to even think of the time spent. |
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