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| How many coats of a shellac (french Polish) in a day? https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=42167 |
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| Author: | Steven Bollman [ Wed Dec 11, 2013 11:23 pm ] |
| Post subject: | How many coats of a shellac (french Polish) in a day? |
I have just put my first sealer coats on my first build. My loft is averaging about 45% humidity and 65ºF. I have a 1lb cut of shellac in 190º grain alcohol. Is there a safe range of number coats per day that folks with experience can recommend? Thanks! |
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| Author: | Goodin [ Thu Dec 12, 2013 8:57 am ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
You will probably get several varying answers to your question. It depends on how thick you applied the coats and your technique. Typically French polish is done in sessions, where after you lay down the sealer coats, you do 3 or 4 bodying sessions then spirit off. After each session I have heard waiting an hour or so before starting the next session. But it probably doesn't matter how many sessions you do in a day as long as you build up thin. You want to use very little shellac when bodying, like almost nothing. Just keep working it until you get wore out then take a break, then when your arm falls off quit for the day. I would suggest sticking exactly to whatever method you are using. I recommend the O'BRien French polishing DVD. Very thorough. |
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| Author: | ernie [ Thu Dec 12, 2013 9:15 am ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
A lot depends on what the conditions are in the room your working in My bsmt is now abt 25% humidity and 58 deg not vy ideal.I/m FP a piece of scrap WRC till it looks right . Warmer temps.= more sessions. I do mine daily. |
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| Author: | Greg B [ Thu Dec 12, 2013 10:39 am ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
Yeah, if you're FP'ing there aren't really coats per se, though most people put it on in 'sessions'. 3 or 4 a day is probably a good rule of thumb, though I would suggest one a day if it's your first time. It's safer and will make things easier. It is actually possible to put it all on in a day. You won't be able to do that without experience though. |
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| Author: | Frank Ford [ Thu Dec 12, 2013 11:14 am ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
If you put on a thick finish by French polishing, you can do it all in a day, but then you have a LONG drying time ahead of you. I've done that sometimes when I knew I'd have to leave the job aside for a month or more. Just like lacquer, shellac is an evaporative finish, and if it's thick it takes longer. High humidity and super thick French polishing might promote blushing or cloudiness. Living where I do, I wouldn't know about that. Some finishers do French polishing with only shellac and NO oil of any kind, and wipe a single pass per day, to avoid the pad or rag sticking. Those folks may take six weeks or more to get the finish all on. That may seem like a long time, but it's only five minutes or less a day for the entire instrument. Like guitar playing, French polishing is all about technique, not materials, and with experience, all kinds of techniques can work well. |
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| Author: | David LaPlante [ Thu Dec 12, 2013 11:57 am ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
I do one "session" per day. This consists of scuff sanding the prevous session with 320, 400 or 600 3M Gold, dry depending on where I'm at in the overall schedule. Then a series of "pulls" with the pad, the shellac being appropriately thinned and loaded into the pad again depending on where I'm at in the overall process. I don't use any oil and can usually get 10-15 sets of "pulls" in any one session by controlling the visosity of the shellac, the amount of material in the pad and how much pressure I put on the the pad as I move it across the surface. One day between "sessions" is usually sufficient drying time. I do the different parts of the guitar in this sequence: -Back, Sides and neck heel- 4-6 sessions (maple vs rosewood) -Top and peghead- 3-4 sessions -Neck shaft 2-3 sessions |
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| Author: | Michael.N. [ Thu Dec 12, 2013 1:02 pm ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
David. That's fast French Polishing (if we can call it that). The technique that you describe (straight lines?) is the method that I use but that's after doing 10 or so brushed coats of very thin Shellac. Do you pad glaze after or do you go through grits and the polishing compound? |
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| Author: | JasonM [ Thu Dec 12, 2013 1:25 pm ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
I put it on thick and frequently on one guitar, to get it off the bench (as I was moving), and it crazed, surface looked like a dried up mud puddle (at a microscopic level). My better french polishes were put on thinner, spaced a day or two apart per session. |
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| Author: | David LaPlante [ Thu Dec 12, 2013 2:31 pm ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
Michael, By the end of the process I pad glaze (with extremely thinned shellac and a very "dry" pad) over the surface which has been sanded (at that point) out to a final 800 grit. It takes several series of passess to completely develop the final surface which is only foam wheel buffed or hand rubbed from that point. My initial coat is a "spit" coat, but the bodying is done as I've described with a heavier cut than used at the middle and especially the end of the process. |
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| Author: | ernie [ Thu Dec 12, 2013 3:23 pm ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
I prefer to flatten halfway through my building up the layers either with 1500 or pumice , depending on how the surface appears. It/s different for everyone.It/s basically a judgment call you might use 600 or 400 grit . Techniques , climate, temp , shellac product/thinner vary widely and from person to person. |
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| Author: | Michael.N. [ Thu Dec 12, 2013 3:27 pm ] |
| Post subject: | Re: How many coats of a shellac (french Polish) in a day? |
Yes it's pretty similar to my method. I rub out at 800G and then do a series of straight lines with very thin Shellac - maybe 5 or 6 very quick sessions of this over a couple of days. Just enough to be rid of the scratches left by the 800G. I don't buff or use any compounds. I'm left with a series of very fine lines left by the cloth, enough to scatter the light. I guess it's like a matte/semi gloss. If I want full gloss I'll rub out with 1200G , do a few straight line sessions and then glaze with a near dry pad. JasonM. I rather like the look of those microscopic mud cracks! |
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