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| AAAAGGHH! The pores! The pores! http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=1278 |
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| Author: | Kelby [ Wed Mar 09, 2005 8:24 am ] |
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Well, on my son's paduak guitar, the laquer has now cured for a week and a half, and along one edge of the back I am seeing pores. AAAAGGGHHHH. I hate pores. In the past, I have always dealt with this by sanding flat and hoping there's enough laquer that I don't sand through. And if I sand through, well, it's a few more coats of laquer, a couple more weeks of curing, and here's hoping it works better next time. Effective, but far from ideal. I presume that I could also try to dab some drops of fresh laquer on the pores and hope that fixes the problem, and if it does sand it flat after a few days. I have never tried this before, but it sounds like other people do it. How well does it work, and are there any pitfalls to watch out for? Any other suggestions. I am probably seeing 25-50 pores along the right side of the guitar's back. (There are no pore problems on the remainder of the back and sides.) I don't think my son would notice one way or the other at his age, but it would bug me forever. And it would bother him when he got older --- he's like me that way. |
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| Author: | Michael Dale Payne [ Wed Mar 09, 2005 9:46 am ] |
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I am assuming that you did not pore fill prior to finishing? If I am wrong, let me know. But if you did not fill prior to adding finish you may find that other spots will appear with time. as the finish shrinks. As far as the fix I would use laquer stick. |
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| Author: | Kelby [ Wed Mar 09, 2005 11:10 am ] |
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Thanks, Michael. I filled the pores with shellac and sanded flat before spraying, but it appears that things weren't as flat in that area as I had thought! I'll give the laquer stick a try. |
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| Author: | Sprockett [ Wed Mar 09, 2005 12:33 pm ] |
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This is why I fill with epoxy, it doesn't shrink and once they are filled you are good to go. If it's only on the back then I would spray, give it a week or so and spray again to cover any other shrinkage and then sand flat. Although you could be doing this for a while :) -Paul- |
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| Author: | Michael Dale Payne [ Thu Mar 10, 2005 3:27 am ] |
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[QUOTE=Kelby] Thanks, Michael. I filled the pores with shellac and sanded flat before spraying, but it appears that things weren't as flat in that area as I had thought! I'll give the laquer stick a try.[/QUOTE] A little warrinig about trying to fill pores with shellac. When you fill with shellac your work will appear perfect. However shellac tends to bridge the pores and not fill them. This is very true on medium and small pore woods. After time the shellac will receed into the pores. If you want a simple level fill system I would use an epoxy fill. I like Zpoxy. I think it realy make the wood pop under both waterborne and nitro finish. I would suspect that over time you will find more areas that shows pores as the shellac receeds. I don't mean to be a dooms day advacate by this is the nature of shellac. Now If you mean that you pumice filled, well that is fine. |
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| Author: | Kelby [ Thu Mar 10, 2005 10:22 am ] |
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Michael, Thank you for your thoughts. I did not use pumice in this case, so I may ultimately regret using just shellac. In terms of bridging, I have not seen any problems from that, and I at this point I'm just sanding laquer and not shellac so hopefully I sneaked past that problem. In terms of receding, I do wory about that, but I take some comfort in the fact that I let the shellac sit for a few months before I sanded it flat and sprayed the laquer, so hopefully it did most of its receding during that time. Next time around, I will definitly try Zpoxy. How difficult is it to sand level after applying? |
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| Author: | crazymanmichael [ Thu Mar 10, 2005 1:33 pm ] |
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I've never tried the epoxy fill route and am leaning toward trying it. Looking around though i've only seen the z-poxy in small sizes that are expensive. What is the usage rate on woods like mahogany or rosewoods? Is it available in larger sizes; and where available ? Equivalent products and where? Thanks in advance. |
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| Author: | Kelby [ Thu Mar 10, 2005 2:03 pm ] |
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I wonder the same thing. Is there anything magical about ZPoxy, or would any instant epoxy work? And to extend working time, how about using West Systems? |
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| Author: | Dave Rector [ Fri Mar 11, 2005 1:30 am ] |
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I've used epoxy from Bob Smith and from System 3 and they both seem to work just fine. The System 3 stuff seems to take a little longer to cure, but I always wait till the next day anyway so it's no big deal to me. |
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| Author: | Michael Dale Payne [ Fri Mar 11, 2005 1:34 am ] |
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It takes me about 1oz of mixed Zpoxy Finishing Resin. (not the 5 min epoxy however it will work but will have a very short pot life) to cover a back and side with one good coat. I have found that in medium and fine grain wood that I only need one coat. More porous woods I use 2 coats, sanding between. I like it better than any fill I have ever used. It is by far the simplest fill. I have a local RC Model Air plane Retailer orders it for me in 10oz bottles. I also use West Sytems epoxys for other epoxy applictions. So the only use I have for Zpoxy Finishing Resin is filling. |
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| Author: | Robbie O'Brien [ Fri Mar 11, 2005 5:51 am ] |
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Have you tried using the shellac with end grain saw dust method of pore filling? You could just do it over that area no where you have the problem and spray more lacquer right over the top. No more pores... |
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| Author: | crazymanmichael [ Fri Mar 11, 2005 9:21 am ] |
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MichaelP How do you apply the z-poxy? At one once per instument the ten ounce bottle is a rather economical filling option. Any special tricks to ensuring good finish adhesion? Michael McClain |
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| Author: | Michael Dale Payne [ Mon Mar 14, 2005 1:22 am ] |
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That is 1 oz per coat per back 3/4 oz per coat for the sides and neck. so on a Rosewood B/S set with mahogany neck 2 coats will be 3 1/2 oz. Some times more if I sand though. If you are judicious about your usage you can do better than this I just squeegee it is with a single edge razor with the outer edges ground round to eliminate gouging. the only real trick is too work from the far edge toward your self to keep from reaching over applied epoxy. Mix only enough at a time that you can apply well before the end of the pot life. |
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