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buffing FP help??
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=8574		 Page 1 of 1
Author:  mikev [ Sat Sep 23, 2006 6:08 am ]
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Ok, I have about 9 sessions of FP on my practice top, I think it is quite nice at this point. Heck almost, but not quite, nice enough. It has been four days sinced I glazed it and time for the buffer.


So I started buffing with a 8" buffer at 1725 rpm using, tripoli bar that came with the buffer and noticed a few of these.




I hope you can see them well, I zoomed in as much as i could.
I think the shellac melted and piled up in ridges. But if so why.
Was it too soon? Did I apply too much pressure, I thought i was not heavy handed? Is the tripoli compound to aggressive? All of the above ??

I tried another wheel with "white diamond" compound and did get a nice luster without any of the shellac melt sandwiches, but I also moved faster and went lighter pressure. I was scared.
Good thing I can sand it off and try again,, but would like to get it at least closer to right next time.

One more question,, is 1 glazing session correct or should there be more.
Thanks,,,, Mike
Author:  A Peebels [ Sat Sep 23, 2006 7:56 am ]
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I don't know but I'll bump your post up to the top.

Al
Author:  Martin Turner [ Sat Sep 23, 2006 9:33 am ]
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Mike,

Im still on a steep learning curve with FP but it could be you didnt leave the body coats sitting for long enough before attacking your baby with the buffer.

Being FP and not laquer I imagine you should be able to work out the ridges without too much trouble.

Michael P (French Polish Superhero) will no doubt be on the scene any minute to save your bacon!
Author:  mikev [ Sat Sep 23, 2006 9:45 am ]
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Martin, thats one of my thoughts, not enought time to cure, but I thought I read 4 days was ok.. I have only ever buffed ktm9 before, and of course waited about a month, maybe I needed to have a much lighter hand here also...
Actually I'm glad it happened... . This is practice, might as well make as many mistakes as possible and learn what not to do,, and how to recover if you make one..I'm sure with a little sanding and another couple sessions it will be at least back to where it was before the buff monster hit, but then I'd like to know how to proceed.
Mike
Author:  mikev [ Sat Sep 23, 2006 11:16 am ]
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hesh, you could be right, it is dirrectly hooked to the motor, so i'd have to do some pulleys to reduce the speed. I felt that with the buffs only being 8" it would be ok,, there is guite a bit less fpm with the 8" then with 12s..What size wheels do you have?? ..just did the math,,, 3620FPM with the 8" @1725 rpm. Thats the same as a 12" @ about 1150 rpm...    Now, i have no idea if thats good or bad, but maybe someone else can tell me if those #'s are good.
Mike
Author:  Dave-SKG [ Sat Sep 23, 2006 11:27 am ]
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I agree with Hesh...buffer rpm too high. Also, I wait about 30 days before taking to the buffer and then only a very light buffing. I use menzerna fine (fmezf) and then very fine (fmezw). Man does that look nice!
Author:  arvey [ Sat Sep 23, 2006 12:00 pm ]
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All my guitars are French Polished (over 100) but I have never used a buffer. I always rub the french polish out after a couple of Days using McGuires #7 . It workes great and produces a very high Gloss in very little time. I suspect that if using a buffer you would have to be very careful and use Low RPM. Personally I would just do it by hand, probably almost as fast and a lot safer. Others will disagree of course.
Author:  letseatpaste [ Sat Sep 23, 2006 12:09 pm ]
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In Brune's class we were buffing inside 20 minutes of finishing with the fp. We didn't use near that speed, though. We used a 8" buffer pad on the drillpress where you're using the face of the wheel, not the edge. I got nervous about my piece flying across the shop, so I even just used a towel and Meguiar's (#7 I think? Do you remember, Robbie O'Brien?) and did it by hand and it turned out great and only took a little bit longer.
Author:  arvey [ Sat Sep 23, 2006 12:26 pm ]
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I do it by hand usingboth #7 and #9 and it takes maybe 1/2 hour.
Author:  jfrench [ Sat Sep 23, 2006 1:11 pm ]
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I usually just dry sand the fp with 1500 grit then buff on the buffing wheel with 3m liquid compounds. Takes like 10 minutes to buff out a guitar, I have never generated enough heat at to hurt the finish at all, and I never wait more than a couple days at most before buffing (often same day). Think I am using 625 rpm... whatever the stewmac setup recommends.

My suggestion - use some 600 grit to dry sand out any imperfection that happened (ridges etc). Polish over it a couple of sessions until those 600 grit scratches are filled with polish. Dry sand with 1500 grit, put a drop of 3m finesse-it over the area, put it on the buffing wheel with moderate pressure, and get yourself a beer to celebrate having fixed this issue with less than 30 minutes worth of work.jfrench38983.9336574074
Author:  MSpencer [ Sat Sep 23, 2006 1:22 pm ]
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Not a FP guy myself, but I have had some "green" varnish and shellac do the same while sanding and buffing. I think the guys who are hand rubbing are giving good advice, buffing wheels freak me out.

Mike
White Oak, Texas
Author:  Colin S [ Sat Sep 23, 2006 9:17 pm ]
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I've never buffed out a FP finish, as I'm not over keen on too glossy a look. After glazing, I hand rub, as in just using the palm of my hand, and find that that produces enough friction and heat to get just the finish I want.

Colin
Author:  mikev [ Sun Sep 24, 2006 2:54 am ]
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thanks for all the input, especially about having the beer . No seriously, i am going to see if I can get 1/2 of it buffed with the finer compound on the wheel and keep the piece moving real fast so no heat builds up.And the other half by hand with liquid. that is if I can remember which box its stored in. It seems apparant that when my shop gets set back up if I still want to use a buffer then I will have to sloooow it down.
Once I get a better feel I will then sand it down to remove the defects and add few more sessions and redo it.

Colin, do you have any lube on your hand, I have read were this is done before, but not sure of the technique. I am assuming your method produces a luster instead of a glass like finish, but not satin either..
Off to practice FP..   Thanks again.
Mike
Author:  Colin S [ Sun Sep 24, 2006 3:08 am ]
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[QUOTE=mikev] .

Colin, do you have any lube on your hand, I have read were this is done before, but not sure of the technique. I am assuming your method produces a luster instead of a glass like finish, but not satin either..
Off to practice FP..   Thanks again.
Mike[/QUOTE]

No Mike just your bare hands, rather like polishing an oil finished best shotgun. Just rub your palm and heel of your hand over the finish, it may even become uncomfortably warm. Yes it finishes with a nice shiny lustre without being too glassy looking, not a finish I like. By the way I have never levelled with abrasives of any type, after bodying, if done carefully and glazed properly that shouldn't be necessary. I believe Frank Ford does something similar.

This is what it looks like shiny and rich without being plasticy looking. In fact it looks French polished.



Colin
Author:  mikev [ Sun Sep 24, 2006 4:22 am ]
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Colin, beautiful Lute,, nice to see it again, the finish is fantastic.. But I don't believe I ever asked how to make an instrument look that good!! ..
I leveled before I glazed, but I really don't think I needed to.. But after glazing I did have some streaks, visible mostly in the Walnut back.. I tried the hand rub/poor mans buffer method and it does look great. As you probably already know,, I still have the streaks. How do I glaze and not get those. drier muneca? More pressure..It feels as though they are very slight ridges. That if why I suspect it was too wet?
Mike
Author:  mikev [ Sun Sep 24, 2006 5:28 pm ]
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well i was able to sand out the top to remove the defects, then applied two more bodying sessions and reglazed. I think th e glaze came out much better this time, and in a few days I will polish it, i will start with hand rub, and possible go on to liguid polish by hand. The photo is with just one overhead light, no flash.

Since my shop is in boxes, i may make just enough room to build a dulcimer out of some walnut I have sitting here... I want to try this for real. Thanks for all the help.
Mike
Author:  Michael Dale Payne [ Mon Sep 25, 2006 12:03 am ]
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A couple things. First I am not sure what grit Tripoli bar is but I really recommend Menzerna compounds. For French polish I use fine and extra fine. Second the damage in your photo shows either excessive heat or excessive pressure. I buff fine Menzerna at 800 rpm and extra fine at 1100 rpm with my belt tension set so that if I dog the part to the buffs the belt will slip and the buff stop.

If buffing a French polish that has been glazed well you will not need much pressure against the buff at all. Time is not the issue at all you can buff shellac same day if you do it right. In fact if you spirited between every body session after the second, and achieved a level surface with out needing to sand to level, you can glaze to a high gloss without need for buffing. Keep in mind that a high gloss glaze will not happen in just a few glazing sessions. If you pay attention to the reflections in the surface you will know that your there when a reflection of light bulb is in true focus on the surface of the guitar. At that point all you would need is a polishing compound like 3M finess-it and no need to high speed buff.

If you want to buff it, keep the pressure moderate, keep the buffs moving to reduce heat build up and use only fine and extra fine compounds.MichaelP38985.419849537
Author:  mikev [ Mon Sep 25, 2006 2:28 am ]
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[QUOTE=MichaelP]
In fact if you spirited between every body session after the second, and achieved a level surface with out needing to sand to level, you can glaze to a high gloss without need for buffing. Keep in mind that a high gloss glaze will not happen in just a few glazing sessions.
[/QUOTE]
Thanks for that info Michael,, I only did one glazing session, although I did spirit off after all the bodying sessions after the second. The Tripoli I used was in the buffing kit from bealle, don't know what grade it it was. I did use it on KTM9 and it did a great job.
So the first thing I will do is add at least several more glazing sessions until it gives a great reflection.
Thank you
Mike
Author:  CarltonM [ Mon Sep 25, 2006 6:42 am ]
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Mike, as Michael said, it is possible to get a very high gloss with the FP process alone (nope, I haven't got there either yet, but I've seen photos!).

I have to say, though, that the glow in your latest photo is quite nice. It has a "hand rubbed" fine-furniture look that's mighty appealing. It's difficult to sell guitars in the U.S. without a glassy shine, but as a craftsman, I'd say that it just doesn't get any better than the finish on Colin's lute.
Author:  Michael Dale Payne [ Mon Sep 25, 2006 7:02 am ]
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I have achieved glassy high gloss final hand buffed FP finish in as little as 6 glazing session and had it take as many as 20. Typical on a guitar for me is 8-10 glazing sessions but I am pretty pick on how in focus the reflection is. I prefer to get there by glazing rather than by buffing on French polish jobs. it is not quick and the more you spirited off during boding the more polished the film is before you start glazing. there in the less glazing required for a high gloss luster.

Once again for those that may want to if buffing a French polish finish to ultra high sheen, start with Menzerna fine at 800 rpm and a moderately light touch and proceed to Menzerna extra fine at 1000-1100 rpm moderately light touch. Keep the part moving on the buff at all times. Heat builds quick if you set in one location.

MikeV, the photo you sent shows a reflection of a work light that is fuzzy around the edges. When the glazing is complete the reflection will have no fuss but be a completely in focus image.MichaelP38985.6700347222
Author:  Robbie O'Brien [ Mon Sep 25, 2006 9:31 am ]
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Let me start by saying Very beautiful Lute Colin!!

Buffing a French Polish successfully has many variables, just like anything in finishing. Many of them have already been mentioned here: RPM's on the wheel, pressure, thickness of coats applied, cure time etc.
When I French Polish I can go to my buffer within a few minutes and buff it out to a high gloss. The pic is an example. My buffer is much higher than 1750 RPM's too. Keep the guitar moving and use light pressure. I use menzerna very fine to get the gloss.
You can also do it by hand using Menzerna swirl remover and a soft cloth. The result is the same and it doesn't take much time to get it to a high gloss. It is also much safer if you don't have much practice on your wheel.
Like Jon said, we learned to use the drill press and a small buffing wheel in the Brune class. I prefer my buffing method as I melted my finish in the class!


Author:  Serge Poirier [ Mon Sep 25, 2006 11:23 am ]
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[QUOTE=CarltonM] (nope, I haven't got there either yet, but I've seen photos!).

[/QUOTE]

Phew, for a second there i was certain you were gonna say that you had stayed at a Holiday inn last night!
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