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| Nitro over waxed shellac? why is this bad? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=31961 |
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| Author: | Dave Livermore [ Sun Apr 24, 2011 2:22 pm ] |
| Post subject: | Nitro over waxed shellac? why is this bad? |
I just searched and found 565 results for nitro, shellac and wax. In many of the posts, I read that 100% dewaxed shellac should be used. However, I can't find anywhere where it said why it was bad. On the bench, ready to spray is an instrument that I got the perfect color tone by spraying Buttonlac on it. The shellac was run through a filter a number of times, but I still don't know if I got all the wax out of it or not. It is definitely still cloudy, but that could just be the nature of the beast. i've not used this stuff before. If it is indeed bad, and someone can tell me what will happen if I spray nitro over it, please also let me know if spraying a coat or two of dexwaxed shellac on top of the non-dewaxed shellac and putting nitro on top of that would be a better (or worse) idea. Thanks, Dave |
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| Author: | Alain Moisan [ Sun Apr 24, 2011 3:08 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Dave Livermore wrote: Nitro over waxed shellac? why is this bad? The wax will prevent the nitro (or any other finish as far as I know) to stick to the shellac. Waxed shellac is good only if it will be the only finish used. Dave Livermore wrote: The shellac was run through a filter a number of times, but I still don't know if I got all the wax out of it or not. It is definitely still cloudy, but that could just be the nature of the beast. Filtering it won't take the wax out. Let it sit for a few days (a week or so) and the wax will lay at the bottom of the bottle. Then you can decant it and get wax-free shellac. NOTE: I've did this in the past and still got adhesion problems. It seems that some pre-made shellac contains other additives that will also prevent other finishes to stick well to it). Dave Livermore wrote: If it is indeed bad, and someone can tell me what will happen if I spray nitro over it, please also let me know if spraying a coat or two of dexwaxed shellac on top of the non-dewaxed shellac and putting nitro on top of that would be a better (or worse) idea. Well, I didn't try it myself, but it makes sens. You could just make some tests on scrap. |
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| Author: | Chris aka Sniggly [ Sun Apr 24, 2011 3:38 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Dave, the best idea would be to use dewaxed shellac to begin with. Personally I can't think of many things that WILL stick to wax. To answer one of your questions though...I suppose that if your coverage were PERFECT (speaking in terms of applying dewaxed over waxed shellac) you probably wouldn't have issues. Still, you have an opportunity to remove a probability from the equation. Best Luck! Chris |
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| Author: | Howard Klepper [ Sun Apr 24, 2011 4:05 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
You would probably be OK spraying nitro over a not-dewaxed shellac base. It's really deadly to the adhesion of water-borne, but the solvents in the nitro will dissolve wax and it will likely bond OK. But you can be more certain by giving the shellac a good wiping with naptha first. |
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| Author: | Dave Livermore [ Sun Apr 24, 2011 5:03 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Thanks for the quick responses. I've been filtering the shellac all afternoon through coffee filters. It was definitely not dewaxed, and is quickly getting clearer and clearer. Will wipe some Naptha on before spraying Lacquer too. Is Mineral Spirits and Naptha functionally the same thing? I thought I read that someplace. Dave |
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| Author: | Chris Pile [ Sun Apr 24, 2011 5:36 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Not to be mean, but you have a computer and Google. My mother calls it, "The Answer Box". |
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| Author: | Dave Livermore [ Sun Apr 24, 2011 6:12 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Thanks for the reminder Chris. I'll be sure and try that next time. |
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| Author: | David Newton [ Sun Apr 24, 2011 6:13 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
You can spray de-waxed shellac over the waxy shellac and then nitro. |
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| Author: | Dave Fifield [ Sun Apr 24, 2011 6:33 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Dave Livermore wrote: Is Mineral Spirits and Naptha functionally the same thing? I thought I read that someplace. Dave Almost the same - naphtha will evaporate faster than mineral spirits though. Dave F. |
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| Author: | Alain Moisan [ Sun Apr 24, 2011 10:32 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Chris Pile wrote: Not to be mean, but you have a computer and Google. My mother calls it, "The Answer Box". Chris, what the heck is that about? It is one of the basis of this forum, don't ever blame a user for asking a question before searching the archive or google or whatever. Everyone is always free to ask whatever question they feel to ask without risking the 'slap on the hand' other forums are prompt to do. |
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| Author: | Chris Pile [ Sun Apr 24, 2011 10:48 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Lighten up, Francis. |
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| Author: | Alexandru Marian [ Mon Apr 25, 2011 7:11 am ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
My experience with buttonlac is that it has clearly more wax than seedlac, which i thought it is odd. Perhaps the buttoning process (:)) concentrates it. I filter it through a coffee filter and the result is pretty much clear, not crystal but enough. The trick is the let it drip on itself, not force it through the filter. At the end there is a lot of white muck left in the filter. I don't see any wax problem when french polishing (if there is too much of it, it gathers on the pad and clogs it fast). My guess is that if you filter it once or twice it is as good as commercially dewaxed in this regard. |
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| Author: | David Newton [ Mon Apr 25, 2011 8:59 am ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
If the thread is moving somewhat from the OP's question... My preference is Kusmi seedlac, and I like to decant the wax away. I probably lose 25% of the whole batch, but after 3 or 4 decantings I will have a very clear shellac.  And that brings up my question: What is it like to french polish with a significant amount of wax in the shellac, and what is the finish product like? What are the downsides of a waxy job? I imagine that the finish stays sticky, but I don't know. |
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| Author: | Alexandru Marian [ Mon Apr 25, 2011 1:50 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Yes seedlac is cleaner. Less muck left in the filter, drips twice as fast. The one I have is quite clear after just one filtering. There has been some discussion in the past about the wax. One builder was wondering if the wax is actually beneficial. I did a bit of FP on a sample using unfiltered and I didn't notice anything funny about the result, except that the muck gathers and clogs the pad, which is not exactly a problem, it needs frequent changing anyway. |
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| Author: | David Newton [ Mon Apr 25, 2011 3:22 pm ] |
| Post subject: | Re: Nitro over waxed shellac? why is this bad? |
Thanks Alexandru, So I did my own test just after I posted that, got a strip of rosewood and used the waxy leavings, the left-over from the last decant, and polished a bit. You know? it actually seemed like it built faster than normal, and dried normal, so far. So why am I going to all the trouble? |
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