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| French polish glazing question http://luthiersforum.com/forum/viewtopic.php?f=10101&t=46348 |
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| Author: | WendyW [ Sat Sep 12, 2015 4:26 pm ] |
| Post subject: | French polish glazing question |
I'm trying to figure out what constitutes a session when glazing. The Milburn instructions say to to cover each section of the guitar with straight strokes from the center to the edge once. Is this a session or do you do this numerous times on the guitar per session. Other instructions I have say to spirit off after every other session for the first 4 sessions and then no more spiriting after that. The Milburn instructions do not mention spiriting when glazing. So questions: 1) How many times over the guitar per glazing session? 2) Do you spirit when glazing? Thanks, Wendy |
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| Author: | Greg B [ Sat Sep 12, 2015 8:20 pm ] |
| Post subject: | Re: French polish glazing question |
First of all, it's the circular motion that is going to lay down the bulk of the shellac. Straight strokes are for the initial spit coat, and for spiriting off, which you do at the end of a session. That being said, straight strokes can be used for build up on the neck, around the bindings, and anywhere else it makes sense. Spiriting off is mostly to remove the excess oil and help level/smooth out any pad marks. Done between sessions. It's critical to do this if using walnut oil. With olive oil you can be more slack. Glazing is the very last step. It puts the final shine on. I use a nearly dry pad using very thin shellac. If you're beginning, you'll probably want to rub out with wet or dry before you do this. It's been years since I read the Milburn tutorial and I don't recall precisely what they consider a session. The time is somewhat arbitrary, and it's important to find what works for you. I typically go over the whole area (say a top or back) 6 or 7 times with overlapping padding, spirit off, and let it rest. It's actually possible to lay down the entire finish in one session, but it's a bit risky as the pad has more chance of sticking and pulling off a chunk of finish. |
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| Author: | WaddyThomson [ Sat Sep 12, 2015 9:45 pm ] |
| Post subject: | Re: French polish glazing question |
There isn't a limit on the number of times you glaze. A glazing session covers the whole guitar, once, though I'm not really sure that's so important. When I glaze I sometimes go over a section more than once in a session. No oil is used when glazing, so no need to spirit off. |
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| Author: | WendyW [ Sun Sep 13, 2015 10:01 am ] |
| Post subject: | Re: French polish glazing question |
Thanks Waddy. I decided to follow the Milburn tutorial this time around after not being very happy with my last few French polish finishes. They do instruct to use oil in the glazing process, but they do not mention spiriting off. The Michael Payne instructions also say to use oil when glazing and he says that he spirits after every other session for the first 4 glazing sessions, and then does not spirit any more after that. That's why I wanted to know how many times over the guitar = a glazing session. |
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| Author: | Greg B [ Sun Sep 13, 2015 11:05 am ] |
| Post subject: | Re: French polish glazing question |
Oh, obviously I misunderstood your question. For me, glazing is once over, but twice is OK. This might be necessary if you've used sandpaper to level. P1500 scratch marks will typically glaze over with one pass. I don't use oil to glaze, though a tiny residual bit on the pad is OK. Oil makes it impossible to tell if the shine is the real surface or the oil. |
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| Author: | WendyW [ Sun Sep 13, 2015 11:11 am ] |
| Post subject: | Re: French polish glazing question |
Thanks Greg, I guess once or twice over it is. I may decide to stop using the oil now anyway. Just curious, how long do you let the guitar sit between glazing sessions? |
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| Author: | Eric Reid [ Mon Sep 14, 2015 12:32 am ] |
| Post subject: | Re: French polish glazing question |
I have a problem with the whole lore and terminology that has grown up around "French polish". Tage Frid's description in his "Fine Woodworking" book is one of the very few I've seen that seems to be written by someone who has done French polishing. At one end, you have elaborate, mystical procedures that result in open pores, holidays, and pad marks. At the other, you have epoxy pore-fill with a gloss of shellac. Pore-filling is a crucial stage. It's easy on Mahogany, Spanish cedar, maple, spruce, WRC (yes, I pore-fill top wood). It's not difficult on Indian rosewood or wenge. Brazilian rosewood is variable, cocobolo is no fun, and neither is padauk. NO OIL is used in pore-filling. No description I've seen even mentions the complexities of pore-filling. "Bodying" is an arbitrary term. You are building the finish up. You can do that in ways that minimize your pore-filling errors, or you can accentuate them. No need for oil. "Glazing". Also arbitrary. Use oil. Use mineral oil. Just a little. I don't think of any of the stages of French polishing in these terms. I don't think of stages. That said, you can make errors in pore-filling that can only be corrected by sanding back to bare wood. The Milburn Bros. tutorial is a wonderfully detailed description. I would avoid it. |
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