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| Should French Polishing Take This Long? http://www-.luthiersforum.com/forum/viewtopic.php?f=10101&t=41318 |
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| Author: | Mark Chinworth [ Thu Sep 05, 2013 8:46 pm ] |
| Post subject: | Should French Polishing Take This Long? |
I have spent two hours every day for the last two months rubbing my guitar. I understand a good French Polish takes a lot of work, but should it really take this long? My process: I grain filled with Z-poxy. Four filling sessions, spreading with credit card, sanding almost back to wood after each session. I have been performing five french polishing sessions and then sanding, five sessions then sanding, etc. Each sanding session I progress to a finer grit starting at 400, then going to 600, 800, 1000, 1500, and 2000. Always lubricating sandpaper with olive oil. I have no way of measuring the film thickness, but after sanding with 1500 was the first time I could get a consistently flat surface everywhere; so I assume I need to do several more sessions. Each session lasts about two hours to cover the back, treble side, neck, top, then bass side. One session per day. The session on each surface consists of: Spiriting off the oil from the previous session: 6-8 drops of denatured alcohol. Bang against my left hand maybe 10 times (my left hand is completely bruised, swollen, and sore by now). Blot on printer paper, make sure just a water mark is left; if too wet keep banging on left hand. Rub the muneca on the surface in straight lines with the grain. I use just enough pressure to see an evaporative trail, increasing pressure each stroke to maintain evaporative trail. Cover entire surface twice. Bodying: Load with 8-12 drops 2# cut shellac, 4-6 drops denatured alcohol, bang on left hand, blot, rub on a tiny bit of olive oil (just enough so it doesn't immediate stick, but still a little drag when I'm moving it around). Start with straight strokes with grain, cover surface twice, again looking for evaporative trail and increasing pressure as I go. Move to circular pattern or figure-8 and go around edges twice. By this time I usually reload. Go in circular patterns or figure-8's on center field of surface, cover surface 2-3 times. By this time the muneca is getting a little dry, but that's okay because I go back to straight strokes with significant pressure and it eventually turns into stiffing strokes. Stiffing: after the muneca stops leaving an evaporative trail, I simply keep rubbing in straight strokes with the grain, and cover the surface twice. My muneca is a bunched up 100% cotton T-shirt material (well worn and laundered) about 1.5" diameter x 3/8" thick. My muneca cover is a 4" x 4" also 100% cotton T-shirt material. I change the cover maybe every third session, because it starts to gum up and won't distribute the liquids evenly. The photo shows progress five sessions after 1000 grit. At this point there are still uneven surfaces with grain texture evident in the shellac, especially on the top. This is my second french polish job, and it took just as long the first time. But I did love the result. So...can I do anything to speed things up? |
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| Author: | Jim Watts [ Thu Sep 05, 2013 9:41 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
It seems long to me, I usually spend 2-3 weeks or so and I know it can be done in a few days. I've never done that though. One tip that's counter intuitive: a one pound cut or lighter builds faster than a two pound cut. I suspect your rubbing off almost as much shellac as your putting on. Lighter cuts flash off faster The guitar looks great though! |
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| Author: | Mike Lindstrom [ Thu Sep 05, 2013 10:17 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
I don't take that long. Of course now that I've said that, the next one will be years! Based on my instruction, and experience, one of the benefits of FP is that you don't need to sand it. Through the process, it levels itself out. I suspect the sanding is undoing a lot of your work. Also, it sounds like you are much wetter than I. Once my muneca is loaded, I use at most a few drops of anything at any one time. Also, I don't remember the specifics, but everything got easier when I switched to wool roving inside, cotton muslin outside, and walnut oil. Maybe that's just when I happened to it my stride, but it sure seemed to help. |
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| Author: | Michael.N. [ Fri Sep 06, 2013 2:47 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
You should not be spending much more than 10 hours working time on the whole thing, including pore filling. People seem to spend enormous amounts of time on these bodying sessions. I think all they succeed in doing is to lay down Shellac but create deeper swirls/ridges - that they then have to remove with abrasives. You can't work a surface for lengthy periods. The shellac doesn't have the time to dry hard enough. You may think that you are laying down a lot of shellac, that might be true but it's not going to be very level. That's when you come along with your abrasive, removing what you put on a few hours earlier. Try switching to shorter but more frequent sessions. I don't spend more than 5 minutes on any one surface. A session on a Back might last 5 minutes at the most. I rarely use any abrasive between sessions, unless there are nibs or another problem. ALWAYS remove the oil, especially if you are letting it dry for a lengthy period. |
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| Author: | B. Howard [ Fri Sep 06, 2013 4:54 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Start to finish including epoxy pore fill and final polish, I wind up about 15 hours or so per guitar. I usually tell beginners to figure as long as 40 hours to do their first one as there is a learning curve. I don't count drops I put in the mouse, I am always working from more shellac to less in each session and in the whole process overall. A well done fp will be very thin, mine measure about 2.5 mills on average when done. As such you will never get a truly flat surface as you do with say a lacquer. It is a hand applied finish and will show traces of the hand that applied it. I also never sand between sessions. I don't use oil, so that is not a problem for me but if you do you must get it all back off between sessions. |
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| Author: | Spyder [ Fri Sep 06, 2013 6:47 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
So what is the best way to remove the oil between sessions? |
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| Author: | Michael.N. [ Fri Sep 06, 2013 7:27 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
With the pad that contains shellac, no oil. The only other way I know is to let the oil rise to the surface and sprinkle Flour on to mop it up. |
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| Author: | Tony_in_NYC [ Fri Sep 06, 2013 7:32 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Spyder wrote: So what is the best way to remove the oil between sessions? This usually removes oil really well for me but I have not tried it with FP yet:  The guitar is looking good. I have never done a FP finish, but I plan to next summer. Good luck with yours. |
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| Author: | mkellyvrod [ Fri Sep 06, 2013 7:45 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Only done three complete guitars + two tops with French polish, but I did not sand between sessions. Can't help but wonder if you're not removing most of what you're putting on each session. Also found that after a session or two, I did not need to use much oil; only applied oil when the muneca started to drag. I would not go with Tony's degreaser method 
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| Author: | WaddyThomson [ Fri Sep 06, 2013 10:56 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Stiff/Spirit off after every bodying session after the second session( Alcohol only added to the pad - straight, firm strokes, preferably with the grain). This will reduce, sometimes eliminate, the need to sand between sessions. 3 - 4 sessions a day, then let it rest over night. Stiff off again before the next bodying session the next day to remove oil that surfaced during the rest. Use as little oil as you can get away with. Less is more in the oil area. Wipe the pad on a finger with a film of oil on it. It's enough to keep the sticking down, if you have sticking problems. Only add oil every 3rd or so load with alcohol and shellac. Always pad the muneca on paper before starting on the guitar. I get the best results when in makes no mark at all on the paper, and I prefer paper towel to hard paper. Work dry and you get faster builds. Polishing wet is the biggest mistake beginners make, I believe. As Michael said it's all counter intuitive. Bodying for 3 to 4 days should be enough, then maybe a day of glazing with 3 or 4 sessions using no oil and a very light mix of shellac maybe 1/2 to 1# mix. |
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| Author: | jfmckenna [ Fri Sep 06, 2013 11:13 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Why are you sanding? There's ya problem. FWIW to quicken it up I brush the shellac on for the first few coats. That will require sanding if you need to get brush marks out. Other wise just spirit and stiff as waddy said. |
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| Author: | TimAllen [ Fri Sep 06, 2013 4:15 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
My guess is that Mark is sanding because some published and on-line instructions say to do it. My experience has borne out this discussion's theme--when I sanded, I just undid what I had spent hours doing. It did remove some of the visible defects, but once I built the film up again, the same type of defects were there again. I had to learn how to apply the finish without the defects. I think there is a school of French polishing, which includes Trevor Gore's approach, where you apply a relatively thick film of shellac, which inevitably results in surface irregularities; then you sand out the irregularities ending up with a thin smooth film. The other school is to apply a thin smooth film with a technique that doesn't create irregularities. Evenly sanding out a film of shellac takes a lot heck of a lot of skill and technique, so there's no quick 'n' easy choice--both methods have a learning curve. I'm only part-way through it, but I'm enjoying the process. |
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| Author: | Michael.N. [ Fri Sep 06, 2013 5:49 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Well it all depends on what effect you want in the finished film. Building up a thick layer of shellac, letting it harden and then sanding it all down will create an effect that I don't care for. It looks too industrial, a very flat plastic look about it. But if that's the effect you want go ahead and use it, it's not that difficult to do. Just very time consuming. That kind of effect isn't traditional French Polishing though. Traditional French Polishing was less Labour intensive. Even on very expensive items of furniture they couldn't afford to spend huge amounts of man hours trying to get that effect. The more organic approach is to build the polish and cut back just before the glazing stage. Normally that would have been done with Pumice. Any use of abrasive between bodying sessions was only used to de-nib. The final glazing is done with the fad only - which often shows very feint marks from the cloth. |
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| Author: | Mark Chinworth [ Fri Sep 06, 2013 6:41 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Wow! I get back from work with plenty of helpful tips. Thanks! Sounds like the general consensus is I'm going too wet and I shouldn't sand. I completed my first several sessions quite dry with only a few drops per load, but I just couldn't get an evaporative trail. I kept increasing the number of drops until I could achieve a trail, and ended up at 8-12. Should I stop worrying about that darn trail? I'm trying to follow the Milburn tutorial which alludes to sanding, but it never gives specific instructions (that I could find) when and how to sand; so I winged it. After several sessions the shellac looks kinda like micro-corduroy texture, so I sand. But this is probably a symptom of my application technique. Jim: I keep my shellac in a jar which is open the entire two hour session. A lot of alcohol evaporates from the jar in that time, and now I have a much stronger cut. I will dilute it today. Good catch. Michael: Should I have a separate pad for spiriting, onto which I never apply shellac nor oil? I have been using the same pad for everything. I'm actually going for the industrial, flat, plastic look - just my preference. Waddy: Pretty close description of what I'm doing; except I'm too wet and sanding too much. On my previous french polished guitar, I final sanded with 2500 then used rubbing and polishing compounds to achieve the final shine after two weeks' dry time. It was (in my eyes) the ideal finish, and I would be satisfied if every guitar I ever make has similar results. That is why I simply repeated the method. Except it did take a very long time, thus the OP. |
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| Author: | Michael.N. [ Fri Sep 06, 2013 7:02 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Use a separate pad for spiriting off. I use glazing shellac in it - very thin shellac. Forget the abrasive. You might need it after the first applications because you've raised the grain. After that you really shouldn't need to touch the surface with abrasive until you've finished all the bodying. Use an abrasive only if there is a problem on the surface. Don't judge the surface until it has been allowed to dry and harden a little - overnight. Big swirls and marks don't look as bad once it's all shrunk back a bit. I don't look for the vapour trail. Load your fad and test it on paper. That will tell you how wet it is. I use 800G at the end and then switch to glazing. I don't use any abrasive or polishing compounds after that. The 800 will leave very visible scratches but the glazing fills them in. If you want super flat and super glossy you will have to put more Shellac on (than me), let it dry and harden for at least a week and then go through your abrasives/polishing compounds. Seriously though. 2 hours on each session is extremely excessive IMO. You will achieve more with much shorter but more frequent sessions. And if you are wanting to rub down there's no need to go through all the grits. That kind of approach is only used at the very end. If you want to rub down between sessions because of excessive swirl marks just use one grit - 600 or 800 should be enough. |
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| Author: | WaddyThomson [ Fri Sep 06, 2013 8:14 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
After pore filling and a couple of spit coats, it shouldn't take more than one or two sessions to already have some gloss on the surface. The rest is build, level and glaze. |
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| Author: | David Newton [ Sat Sep 07, 2013 10:43 am ] |
| Post subject: | Re: Should French Polishing Take This Long? |
The last guitar I finished with lacquer was in 2005, I have been french polishing shellac on everything since. I'm still learning. You may be trying to approximate a "lacquer thick" finish with shellac. It is hard to get a "thick" shellac finish by french polishing. As far as time goes, I can polish 2 instruments faster than 1, because I will rotate between the 2, and each will have a few minutes to harden between rubs, and the finish will build up faster. So, do shorter sessions, but more of them, letting the last session dry a few minutes. Sorry, I didn't read Michael N's post above, so... what he said! |
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| Author: | gxs [ Sat Sep 07, 2013 6:15 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
+1 on the wool in the pad. When I switch to a strip of wool sock wrapped in old t-shirt it made all the difference in the world. I started one with only t-shirt and then switched to wool wadding after making little progress. BTW, I think your guitar looks great. Another thing I noticed is that the finish will harden for few weeks as the remaining moisture escapes, so trying to get it perfect within a day by sanding has you doing things you may not need, it will flatten out on it's own (to a certain degree) What looks thick actually thins and hardens. Last note, I am a bit of a granola eater, so I don't like harsh chemicals - I have been using Everclear and 151 rum to mix the shellac and it works wonderfully. It smells fantastic and also reduces stress. Try the wool, I think you will see a big difference. Have fun. Geo S. Mike Lindstrom wrote: I don't take that long. Of course now that I've said that, the next one will be years!
Based on my instruction, and experience, one of the benefits of FP is that you don't need to sand it. Through the process, it levels itself out. I suspect the sanding is undoing a lot of your work. Also, it sounds like you are much wetter than I. Once my muneca is loaded, I use at most a few drops of anything at any one time. Also, I don't remember the specifics, but everything got easier when I switched to wool roving inside, cotton muslin outside, and walnut oil. Maybe that's just when I happened to it my stride, but it sure seemed to help. |
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| Author: | gxs [ Sat Sep 07, 2013 6:22 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Brian, I love the hand applied look. It looks like a human made it. I think it is beautiful and personal. B. Howard wrote: Start to finish including epoxy pore fill and final polish, I wind up about 15 hours or so per guitar. I usually tell beginners to figure as long as 40 hours to do their first one as there is a learning curve. I don't count drops I put in the mouse, I am always working from more shellac to less in each session and in the whole process overall. A well done fp will be very thin, mine measure about 2.5 mills on average when done. As such you will never get a truly flat surface as you do with say a lacquer. It is a hand applied finish and will show traces of the hand that applied it. I also never sand between sessions. I don't use oil, so that is not a problem for me but if you do you must get it all back off between sessions.
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| Author: | jfmckenna [ Sat Sep 07, 2013 10:25 pm ] |
| Post subject: | Re: Should French Polishing Take This Long? |
Mark Chinworth wrote: I'm trying to follow the Milburn tutorial which alludes to sanding, but it never gives specific instructions (that I could find) when and how to sand; so I winged it. . I almost always refer to this tutorial as it's about as good as it gets but I have avoided the sanding, or lets say,,, one should use sanding only if necessary. He does talk about it in the final leveling, not between coats. Final leveling takes place after 10 or more body sessions. But it's ONLY necessary if you see ridges and that sort of thing. It's just going to be a process that you need to figure out. Those of us with experience can make suggestions but they are meaningless until you try it out and see what we mean. |
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