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So I've been testing my FP technique on some scrap maple and I now have some questions. My muneca seems to get "glazed" pretty quickly. It seems to develop a shiny patch that kind of scratches as I go. Is this indicative of my shellac/ alcohol mix being off? Also, the clouds don't really seem to be evaporating I just see little circles like it's just getting smeared around. It is mostly shiny and smooth though but how do you tell when you're actually building and not just smearing it around?

Jason, I'm still struggling with FP like you, so I'll wait for the more-expert folks to drop in to this discussion, to answer your main question; "What causes glazing of the muneca cover, and how can I avoid it?". (I'll be watching.)
You are definitely on the right track, paying close attention to what is happening at the surface, rather than just grinding away.
One idea that took a while to 'sink in' for me was that I needed to change the muneca cover more often, keeping the 'core' with its load of shellac. If the cover is large enough, sometimes I can get away with just shifting it to a 'clean' area. I keep a small 'stack' of covers handy now. I've also found that different fabrics for the covers work differently for me, so some experiments there can help.
Finally, when I got some in-person instruction I realized that I'd been 'rubbing' way too hard - FP is physical, but not a great deal of pressure is required, it seems.
I don't know if any of these ideas will get you closer to solving your problem!

Cheers
John

Thanks John. This cover got that glazing in only a couple of minutes. I'm using an old bed sheet as my cover and cheesecloth for the wadding. I'm also using walnut oil for the lubricant if that helps any. My gut feeling is that I'm not using enough alcohol or maybe too much oil. I'm using about equal parts shellac to alcohol and I just dip the tip of my finger in the oil and lightly rub it on the bottom of the muneca.

If you are getting a vapor trail, and it's not going away, you are too wet. If you aren't getting one, you are too dry. You'll get some glazing on the muneca cover. I, sometime, turn it inside out, and re-use. You do have to change it fairly regularly. Another thing I do is make mine a bit too big, and move the core around on the cloth to an adjacent segment. I can move it several times and get a new surface. Then if you turn it inside out, you can get a few more times. I use Walnut oil too.

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Waddy

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Waddy is dead on. If you see a trail that does not dissipate near instantly (notice I did not say vapor trail) you are far too wet. The reason I did not say vapor trail is because that is not what you are seeing. if it was the perverbial vapor trail it would dissipate with in a half inch of the the path of the muneca because it is alcohol flashing off out of the applied shellac. If it does not dissipate within 1/2" behind the path of your muneca then you either have far too wet of shellac or far too wet of alcohol and what you see is a thin liquid path of shellac. not a vapor trail. the french polish process is a far dryer process than most expect. this is part of the difference between padding on shellac and French polishing with shellac.

My guess is you have a misunderstanding of really how the muneca works. in French polishing it is a wicking of residual shellac from the inner pad through the outer pad that is applied to the surface during boding. Not the new load you apply to the muneca. Each new load is to be tapped into the inner pad to form a wicking channel from the inner pad through the outer pad. The consistency of the shellac being applied to the surface should be like a very soft past wax. Never liquid in appearance.

I have a tutorial in the tutorial and video sections here that you may find of help

In regards to your muneca glazing over and causing scratches. Well you should be changing outer pads more often and you should never let you muneca set unused in the open for any length of time. When not in use store in an air tight container. I change outer cover typically 8 times during boding a guitar to full thickness. Sometimes more on hot dry days.

typically if you load the muneca too liberally and not in the center of the pad and allow it to run over to the edges you will get a crusty section where the muneca in never in contact because the air dries the shellac, and the this part of the loaded shellac never gets tapped in. you can learn to load so that this is kept to a min.

Jason

Here is a link to my tutorial I spoke of
http://luthiersforum.com/forum/viewtopic.php?f=10117&t=25507

Thanks Michael and Waddy. I've been blotting on paper first to see how much shellac is coming out. I thought I was dry enough as it didn't leave much of a mark but I tried it a little drier and changing my pad more often and that seemed to do the trick. I do keep the muneca in a jar.

When you tap you mudeca after a load you want to tap till the report is spotty (bunch of dots; not a solid report)

Is it possible that your loaded inner pad was not allowed to harden enough before use? You don't want the inner pad to be wet you want it throughly saturated when you first make it let it drain till it does not drip, then allow it to harden for several hours or over night before use. you want the inner pad to feel like soft toffee before you use it. That way when you add a fresh load durring bodying; the new load will partially melt the partially hardend shellac of the inner pad and start the wicking process. The actual cut will be thicker than the 2lb cut. This means the consistancy of the shellac being applied to be like a thin paste wax not like a liquid.

Really good points from Michael and Waddy.. The tutorial is a good start for anyone and
a nice way to brush up on the fine points for those who have done a few guitars.
Some things I've learned FWIW:

1. Choose a good material for the pad, never had any luck with old tee shirts. Some
old pillow case materials work, linen is good as well. I think that material will affect how
often you'll have to rotate the contact area or change the pad. I cut a pad that's about
8 inches square so I have quite a bit of surface area to change to as I work. If you really notice a difference when you change to a new pad or change the area of the pad you are working on, you've probably gone too long.
2. The minute I'm done with the pad it's back in the storage container and the container
has a few rags soaked, but not drenched, with alcohol. Just enough to keep the pad from
drying out and keeping it fresh and ready to go. It's amazing how hard the pad will get
when you toss it out, and in a very short time.
3. It's a real balance between a charged muncia and a soaked or dry one. It's only time
and experience that helps build the skill to know the difference. The two working together
is the secret to good french polish technique. I find that when I hit the perfect combination
of pad/inner pad/alcohol that I really need very little oil. To me, the less oil the better.
4. It can be easy to produce a dry spot, where you have pulled the finish off an area
and are nearly on bare wood. I've found a couple of ways to deal with this. I have brushed
in shellac on that spot, sanded it with find paper and oil and gone back over it.
Sometimes you can fix those areas buy just using different pressure there and concentrating
on adding material, then smooth things out with a spiriting pad. That has worked for me.
5. One of the hardest things to remember is that your edges are always going to require more work than the center areas. So I start and finish there, it seems to help.
6. The more I work with shellac, the more I find that the finish or polish that I want is
best achieved by spiriting off rather than sandpaper. I've found it too easy to sand, even
with micro grit papers, and find that you have a surface that's not uniform, you can see areas of previous applications. This is not something I've run into with good spiriting off
and final polish with a good polish like Meguires #7.

Just some thoughts, maybe they will make sense and be of some help to someone.
Thanks again to those who have shared what is obviously many years of experience.
Best
Bruce

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Bruce Herrmann
"What lies behind us and what lies before us are tiny matters compared to what lies within us."

Bruce most of what you wrote is all good info. I will add though it is never a good idea to sand, more so with oil as a lube while still building the film thickness. If you stick and pull off finish a quick spirit off of the area, body the area, spirit off the area body the area till you have build back up to major level. work from the outside of the removed area inward or you will create a creator. Spirit-off till all is blended is the best way to repair the spots.. It should take one or 2 drops of oil per load or even less depending on your cut and ratios as well as ambient temp and RH. these are things that change and one must learn to adapt by paying attention to the consistency of the shellac build up and learn to adjust.

In my opinion t-shirt material is about the worst suitable material to use. It is a 3D stretchable weave tht can trap old dyed shellac, dust and other contaminates. I prefer high thread count linen or muslin as my outer cover. Also once you understand that it is the residual shellac in the inner pad that you are wicking through the outer pad and laying down on the surface you will understand that the inner muneca material is just as important as the outer muneca material. I find the natural non-dyed cleaned wool roven to be the best inner muneca material. It has a high fiber count per mass it hold a good amount of residual shellac. It wicks well and is easily formable.

Thanks Michael, great info. I've learned a great deal from your posts, as well as others
here.

_________________
Bruce Herrmann
"What lies behind us and what lies before us are tiny matters compared to what lies within us."

I have been applying French Polish to a guitar for the first time and learned the hard way that I tend to add too much shellac to the pad. Now besides patting the muneca on paper I take a few test passes on a practice board, that way if the pad is too wet rather than wreck a spot on the guitar that takes a while to repair I have only hurt the sample board. Also I have found sand paper can be quite useful especially during the pumice part if you get a pile going it is better to knock it down with some 600 and naptha as a lubicant than to try and rub it away with more shellac. The sand paper also is helpfull if you get tiny threads in the finish just as you working up the shine. The naptha is nice because it will evaporate very fast and you can wipe off the shellac dust and continue polishing. I have really been struggling finishing around the bridge as it is diificult to get enough shellac in the inside corner. Yesterday I used a airbrush to spray about 1/4 inch around the bridge and it looks great now. The shine you can work up is truly amazing. Jeff

Michael and/or Bruce:
I'm trying to French Polish my first top, the body is painted normally. I have spent two afternoons bodying and spiriting and its starting to look like something. I'm doin' just the top on a jumbo and I've got four or five hours in it now. Is this a normal amount of time to be at the (maybe) half way point? Perhaps I'm taking off as much as I put on ?
(I dunno )
Any help would be appreciated greatly......
Mikey

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The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

Hello Michael,
I'm curious from the point of view of commerce; What percentage of your guitars are French polished and is it something you charge extra for if requested?

Best

Most use 6-8 body sessions to build the basic film thickness and 5-6 glazing session to build the sheen. If you plan to level sand with sand paper I shogest 10-12 body session as you will remove a good bit of shellac sanding. I don't recommend level sanding but rather spiritting off after every body session. Check my frech polish tutorial revisited for more info.

A very low percintagee of commissions are French polished I build mostly steel string and almost exclusivly commission builds. 98% of my clientel want nitro or cat poly. That said i do have some clients that I have had for years that want only Fp. and all my personal builds for myself are Fp or a FP/nitro combo.

I only charge extra if it is a combo (nitro or other hard fininish back abd sides and FP top)

For those with questions about FP, probably most of us, Michael's upcoming FP would answer most if not all of those questions and make the FP process easy for you.

I was just reading on another forum about adding 2 parts of acetone to one part of the 2# shellac cut. Has anyone here ever tried this? Does anyone feel that it helps/hinders the hardness and rate of drying? I am afraid to try it due to my lack of experience with this process...... Mike

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The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

Personally I doubt it would change the hardness because after the acetone and the alcohol has flashed off you are still left with shellac. Adding other resins will change the film but solvents flash out. To make shellac film harder than it normally would be you have to permanently change its molecular structure.

As far as it hardening quicker I might be able to see that as you would then have basically a .66# cut if you use 2 parts acetone to an already made up 2# cut. you are just adding more solvent to the cut. basiclly you now have 2/3rds solvent and 2/3rds of the solvent is acetone Granted a very fast flashing solvent but a solvent none the less.