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| Problem with 2k acrilic lacquer,please help me https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43025 |
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| Author: | milance21 [ Sat Mar 22, 2014 6:11 pm ] |
| Post subject: | Problem with 2k acrilic lacquer,please help me |
A have problem with lacquer.a sprey 8 coats of lacquer,and after wet sandin a have shini spots,in fack a see shini forms like annual rings of trees (but on the other hand it hase no relation with tree ring patern). If a keep sqanding some of them disapers but new one come out.finish is perfectly flat,a can buf the to mirror finish but,if you look finish in some engle you can see these form.where a get wrong? |
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| Author: | Clay S. [ Sat Mar 22, 2014 6:19 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
I am not familiar with that finish, but some finishes show "witness lines" when you sand through different coats of the finish. That may be what is happening. |
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| Author: | B. Howard [ Sun Mar 23, 2014 8:13 am ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
Yep , witness marks. The boundaries between layers of coating are showing. This can be a problem with Poly type coatings that do not readily "melt " together. |
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| Author: | milance21 [ Mon Mar 24, 2014 3:26 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
how to avoid the problem....does any one have solution.thanks a lot for replies |
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| Author: | Tim L [ Mon Mar 24, 2014 5:08 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
Sounds like you sanded through the final coat like the others said. You can avoid it by having everything flat before you do the flash coat and minimal sanding afterwards. |
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| Author: | TonyKarol [ Mon Mar 24, 2014 5:25 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
Most cross linking finishes, like polyurethane and polyester and possibly acrylic, not sure, never used the stuff, need to be sprayed in multiple coats before they actually cross link .. the schedule is usually something like 4-4-3 or 4-3-4, where you shoot the first 4 coats in quick succession, with whatever the manufacturer says from a time period basis, such that they cross link as one thicker coat. Then you flat sand after 4 sprays, then shoot the next 3 or 4 and repeat. You cant let each coat dry and then shoot the next ... that leads to the witness lines you see ..check the manufacturers recommended shoot schedule. |
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| Author: | Mike Franks [ Mon Mar 24, 2014 8:11 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
How much time between coats? Depending on your temperature and mix formula, waiting more than 24 hours between coats could be your problem. http://www.mjfranksguitars.com |
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| Author: | milance21 [ Wed Mar 26, 2014 4:05 am ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
these first 6 coats a spreyed in this dinamic.first 3 on every two hours ,then waith 24 hours and then again 3 coats on every 2 hour,and again waithing 24 hours,and again next day new 3 coats. |
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| Author: | John Arnold [ Wed Mar 26, 2014 12:20 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
I have never had witness lines with the conventional lacquers I have used (automotive acrylic, nitro). I use a similar spraying schedule, where I spray 4-5 coats, wait 24 hours, level sand, then spray more coats on the porous hardwoods. |
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| Author: | Tim L [ Wed Mar 26, 2014 12:52 pm ] |
| Post subject: | Re: Problem with 2k acrilic lacquer,please help me |
I have had the problem sanding through on the final flash or gloss coat which is about a 50/50 mix. I watched the hazy figure enlarge as I tried to sand it out. Had to sand a bit more as I was leveling a couple of drop fills that had been missed. Would gave been better off ignoring the drop fills. The haze was only visible from certain angles. Tim |
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