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| Lacquer issue http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=36433 |
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| Author: | Lindamon [ Wed May 09, 2012 1:32 pm ] |
| Post subject: | Lacquer issue |
Okay, after spraying nine guitars with no issues, I now have one that is a little frustrating. Everything was fine until buffing. On the same spot on both sides of the guitar, just above the lower bout I have some pitting. After spraying I let the guitar sit for two weeks , wet sand with 800, and buff with medium and fine menzerna. Nine guitars done this way have turned out very well. After wet sanding this one, it looked fine, but when I buffed I got these pits in the finish, and it actually felt rough, the lacquer had also become slightly bumpy, when I first sanded it it looked like orange peel, though none existed after the initial sanding. I was able to sand it down smooth again, but once again when buffing the same thing happened. After sanding it down to the shellac undercoat in a spot, I put three heavy coats on the area with a touch up gun and tried again. Same thing happened. This time I sanded it down and tried drop filling the pits, though they are very tiny. I am going to use my regular HVLP gun to shoot some more coats on, but thought I would ask here if anyone had a clue to what is happening. The wood is maple, with shellac under nitrocellulose lacquer. Could it be possible I got the lacquer too hot when buffing in that spot? It's the only thing I can think of for why it would only happen in that area. I was more careful not to let it get too warm the second time around, but it still happened. Fixes? Thanks for looking! Attachment: IMG_1856.jpg
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| Author: | B. Howard [ Wed May 09, 2012 3:08 pm ] |
| Post subject: | Re: Lacquer issue |
Sounds like some type of contamination in the wood since it happened at the same spot on both sides of the guitar. The shellac should have sealed almost anything in regards to sap or resins in the wood so my guess would be some type of oil may have gotten spilled on the wood at some point, possibly even before it was cut into sides. |
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| Author: | Barry Daniels [ Wed May 09, 2012 3:28 pm ] |
| Post subject: | Re: Lacquer issue |
I agree with Brian. It also could be something that touched the guitar in these areas before you applied the lacquer. Before your strip it down and redo the finish you could try to drop fill again with lacquer, shellac, or superglue (definitely give thin superglue a try). Just might work. |
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| Author: | Lindamon [ Thu May 10, 2012 9:02 am ] |
| Post subject: | Re: Lacquer issue |
Thanks guys, i am trying the superglue and more drop filling to see what happens. |
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| Author: | DavidFreeman [ Fri May 11, 2012 9:06 am ] |
| Post subject: | Re: Lacquer issue |
If you ever go down to the wood again , try wiping it with Naptha , alcohol & acetone before refinishing, . If the wood is contaminated on eof those should clean it up . The other thing I wondered about is if there is extreme runout that leaks air between the body & the outside when you are spraying. I don't seal the soundhole real tight so the body can breath. It is curious that it keeps returning. |
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| Author: | Stuart Gort [ Fri May 11, 2012 12:37 pm ] |
| Post subject: | Re: Lacquer issue |
I had a similar sounding issue occur on my first guitar with nitro over maple. Maple shouldn't present any particular problems as a species. I just had to learn to be careful about touching a freshly sanded surface. Now....I make it a point to seal the surface immediately after sanding....with a Z-poxy washcoat...or two. I sanded down the orange-peeling area back down to the wood and re-sprayed. It turned out nice but I'm not sure how I would have handled it if there were pores to fill. Lucky for me it was maple. |
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| Author: | npalen [ Fri May 11, 2012 9:32 pm ] |
| Post subject: | Re: Lacquer issue |
Is it possible that the lacquer was applied too heavily in these areas and the result is solvent popping creating the pin holes? Perhaps think about your spraying routine and whether or not that might be a possibility. |
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| Author: | Lindamon [ Tue May 15, 2012 1:39 pm ] |
| Post subject: | Re: Lacquer issue |
npalen wrote: Is it possible that the lacquer was applied too heavily in these areas and the result is solvent popping creating the pin holes? Perhaps think about your spraying routine and whether or not that might be a possibility. You know what, I think you might be on to something here. When I spray the sides, as I get to that part of the guitar, I tend to stop moving my arm and rotate my wrist as I spray the waist, then once through that, continue my arm moving around the guitar to the tail. I have noticed the lacquer building more in those areas, though not to the point of runs or anything. I think I am going to turn down the spray more, so I can move more slowly and concentrate more on an even coat. After drop filling and sanding and respraying and sanding a few times it seems to be getting much better! Thanks! |
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