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| Problems finishing rosewood http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=32823 |
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| Author: | Phillip Patton [ Sun Jul 10, 2011 9:11 pm ] |
| Post subject: | Problems finishing rosewood |
Hey all, I've made two guitars out of Indian Rosewood, and both had the same problem. The problem is that the lacquer won't get hard. I've used the same brand of lacquer (Sherwin Williams) on other woods with no problems. I've used lacquer from the same can, even, on rosewood and walnut with completely different results. It just seems to be curing verrrry slowly. Anyone ever run into something like this? Thanks, |
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| Author: | bluescreek [ Sun Jul 10, 2011 9:25 pm ] |
| Post subject: | Re: Problems finishing rosewood |
no usually it dries to touch within the hour. What thinner you using and what retarder ? |
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| Author: | Phillip Patton [ Sun Jul 10, 2011 10:17 pm ] |
| Post subject: | Re: Problems finishing rosewood |
bluescreek wrote: no usually it dries to touch within the hour. What thinner you using and what retarder ? I'm not talking about drying to the touch. It does that just fine. I'm talking about after letting it cure for a month, it fails the fingernail test. |
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| Author: | woody b [ Mon Jul 11, 2011 5:37 am ] |
| Post subject: | Re: Problems finishing rosewood |
Are you using lacquer or some kind of polymerizing finish. (like polyurethane or varnish). Most polymerizing finishes don't cure properly on oily woods like Rosewood. Lacquer cures by evaporation, and should cure on any type wood. I don't know if hybrid finishes (like urethane/lacquer blends) would cure properly or not. |
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| Author: | Phillip Patton [ Mon Jul 11, 2011 7:40 am ] |
| Post subject: | Re: Problems finishing rosewood |
woody b wrote: Are you using lacquer or some kind of polymerizing finish. (like polyurethane or varnish). Most polymerizing finishes don't cure properly on oily woods like Rosewood. Lacquer cures by evaporation, and should cure on any type wood. I don't know if hybrid finishes (like urethane/lacquer blends) would cure properly or not. It's definitely lacquer. |
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| Author: | Tom West [ Mon Jul 11, 2011 10:25 am ] |
| Post subject: | Re: Problems finishing rosewood |
Phillip: Wonder if you are spraying directly on the wood or are you using a sealer.If your going direct ,try a seal coat of shellac as a test run on some rosewood. Tom |
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| Author: | Phillip Patton [ Mon Jul 11, 2011 11:25 am ] |
| Post subject: | Re: Problems finishing rosewood |
Tom West wrote: Phillip: Wonder if you are spraying directly on the wood or are you using a sealer.If your going direct ,try a seal coat of shellac as a test run on some rosewood. Tom I think the first one had no shellac (might have had a seal coat though), and the second one had the pores filled and seal coat with shellac. |
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| Author: | woody b [ Mon Jul 11, 2011 11:32 am ] |
| Post subject: | Re: Problems finishing rosewood |
It sounds to me like something is wrong with the lacquer. The oils in rosewood shouldn't interfere with lacquer curing. (Right John????) I'd contact Sherwin Williams. They're usually helpful, if you can get the right person on the phone. |
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| Author: | Laurent Brondel [ Mon Jul 11, 2011 11:35 am ] |
| Post subject: | Re: Problems finishing rosewood |
If you want to stick with lacquer only you want to seal the rosewood with one or two coats of lacquer thinned 1:1 with lacquer thinner, then spray your normal lacquer schedule. There are millions of lacquers out there, have you tried the Sherwin Williams on instruments before? The proven ones are McFadden (or whatever name it has now) and Behlen's. No issue spraying directly on wood with those. What you describe sounds like you sprayed your coats too fast and/or in too humid conditions, the underlayers haven't fully cured yet. |
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| Author: | Howard Klepper [ Mon Jul 11, 2011 1:13 pm ] |
| Post subject: | Re: Problems finishing rosewood |
Sorry to belabor this point, but are we talking about nitrocellulose based lacquer that is thinned with "lacquer thinner"? Can you name the product other than that it is by Sherwin Williams? Sorry again, but the word 'lacquer' gets tossed around loosely these days, like so many other words. Also, what is your "fingernail test?" A month old nitrocellulose lacquer finish is easily dinged with a fingernail. |
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| Author: | bluescreek [ Mon Jul 11, 2011 3:26 pm ] |
| Post subject: | Re: Problems finishing rosewood |
Good point Howard. There are many types of lacquer. I have used Shirwinn Williams for years without any issue . I stopped shellac for a sealer a long time ago and use the recommended sealers from the companies . Acrylic lacquer is different from Nitrocellulose that id different than Water Lacquer. Nitro Lacquer will take about 3 weeks to cure. |
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| Author: | Phillip Patton [ Tue Jul 12, 2011 3:02 pm ] |
| Post subject: | Re: Problems finishing rosewood |
It's definitely nitrocellulose lacquer. It's the same stuff that Mr. Hall has used. Sorry I can't remember the name of it. I'll try to notice next time I'm in the shop. Whoever suggested that I may be putting it on too thick might be right, though the first guitar I did that has a problem was strung up on Feb 1st, and still seems soft. I used lacquer thinner to thin it. Don't think I used and retarder, since it was the middle of winter. |
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