French Polishing Question

davegardner0 · #1 02-02-2017, 06:43 PM

Hello,
I'm working on a french polish finish for an electric guitar....yes I know this is the acoustic guitar forum but it seems like there is a lot more french polish expertise in the acoustic world so I thought I'd ask here. I hope that's okay!

Anyway things are going pretty well with my finish, which is over aniline-dyed maple. I'm starting to get a nice gloss, BUT over the last few sessions I've noticed that I'm getting tiny fibers embedded in my finish. It seems like the finish is pulling out pieces of the polishing pad. The pad I'm using is a cheesecloth core with a piece of a well worn bedsheet as the cover.

I've tried using more oil, less pressure, etc., but I'm having a hard time keeping this from happening. A session will be going along well, and then all of a sudden I get a bunch of these things in the finish. I can wet sand with 800 grit to remove them but then of course I'm starting over on my gloss. I can't seem to get 3-4 sessions in a row without this happening so I feel like I'll never finish the guitar!!

So, has anyone run into this? Any tips out there? Thanks so much for the help.

Here are a few close-up photos where you can see the issues...

funkymonk#9 · #2 02-02-2017, 08:43 PM

2 things:
obviously try a different cloth for the cover.
And after a session about an hour, are you spiriting the finish with just denatured alcohol?
After a session after an hour just lightly pad the cloth with a few drops of alcohol in straight swipes across the finish and it should clean the finish before your next session.
But I would try a better pad, it shouldn't be leaving anything on the finish.

How much shellac, alcohol and oil do you apply to the pad when starting a session?

Ned Milburn · #3 02-02-2017, 09:39 PM

F.Polishing - The key is balance. If you are getting stickiness, you may have too much shellac in the pad, or too much alcohol. [ Better stated: Too much stickiness is usually too much shellac, but you can wash fibres out of the pad if you use too much alcohol, and those washed-out fibres end up embedded in the surface of existing shellac. Hence, it is a matter of balance. I "build" a skin on the cover with alcohol and sometimes pumice. Then I use this skin until it goes out of balance and move to a fresh spot on the cover. Different cotton performs differently. Try to find one that works, and stick with it. Froot of the Loom cotton has given me good results, as well as cotton of unknown origin. ]

Change the pad's cover fairly often. I use olive oil. I've tried others, but keep going back.

It is easy to drop cloth fibres after you have a good build of shellac. This is when you can move back to a thinner mixture for glazing.

Don't be afraid too use lots of oil. You don't NEED lots, but more oil is preferable than too little.

Once you get the pad to equilibrium, then only slight top-ups are necessary.

B. Howard · #4 02-03-2017, 06:51 AM

I always use new clean cotton for my pads! And change them before they fray and shed fibers. here are some more of my thoughts on FP
http://howardguitars.blogspot.com/20...ional-way.html

davegardner0 · #5 02-03-2017, 10:50 AM

Quote:

Originally Posted by funkymonk#9

2 things:
obviously try a different cloth for the cover.
And after a session about an hour, are you spiriting the finish with just denatured alcohol?
After a session after an hour just lightly pad the cloth with a few drops of alcohol in straight swipes across the finish and it should clean the finish before your next session.
But I would try a better pad, it shouldn't be leaving anything on the finish.

How much shellac, alcohol and oil do you apply to the pad when starting a session?

Thanks for the info. I have been changing the cloth cover, maybe every 2-3 sessions but it doesn't seem to matter. I've tried spiriting off with Alcohol, which works okay and doesn't seem to leave more threads but also doesn't remove any. It does knock down my gloss some. I also had good luck removing the oil (using walnut oil) with a tiny bit of Naphtha.

As far as how wet the pad is - blotting on some white paper leaves an impression, I'll try to take a photo next time to show you.

davegardner0 · #6 02-03-2017, 10:53 AM

Quote:

Originally Posted by Ned Milburn

F.Polishing - The key is balance. If you are getting stickiness, you may have too much shellac in the pad, or too much alcohol. [ Better stated: Too much stickiness is usually too much shellac, but you can wash fibres out of the pad if you use too much alcohol, and those washed-out fibres end up embedded in the surface of existing shellac. Hence, it is a matter of balance. I "build" a skin on the cover with alcohol and sometimes pumice. Then I use this skin until it goes out of balance and move to a fresh spot on the cover. Different cotton performs differently. Try to find one that works, and stick with it. Froot of the Loom cotton has given me good results, as well as cotton of unknown origin. ]

Change the pad's cover fairly often. I use olive oil. I've tried others, but keep going back.

It is easy to drop cloth fibres after you have a good build of shellac. This is when you can move back to a thinner mixture for glazing.

Don't be afraid too use lots of oil. You don't NEED lots, but more oil is preferable than too little.

Once you get the pad to equilibrium, then only slight top-ups are necessary.

It's possible I have too much Shellac in the pad...I've been pretty much adding equal parts 2lb cut shellac and ethanol. Maybe now that I'm building a good gloss I need to tone down the shellac?

As far as the oil I've been trying to use a lot (I'm using walnut oil). But then it becomes tough to tell if I have the ghost of evaporating solvent following the pad or not. Should the ghost be present now that I have a good and level build of shellac that I'm trying to shine up? Or do I need to have the pad dryer than that? hmmm

Also regarding the cover, do you recommend stretchy jersey fabric, like from a t-shirt, or non-stretchy fabric from a bedsheet or regular shirt? Is there much difference there? I've been using non-stretch but not for any scientific reason...

Ned Milburn · #7 02-03-2017, 11:20 AM

Quote:

Originally Posted by davegardner0

It's possible I have too much Shellac in the pad...I've been pretty much adding equal parts 2lb cut shellac and ethanol. Maybe now that I'm building a good gloss I need to tone down the shellac?

As far as the oil I've been trying to use a lot (I'm using walnut oil). But then it becomes tough to tell if I have the ghost of evaporating solvent following the pad or not. Should the ghost be present now that I have a good and level build of shellac that I'm trying to shine up? Or do I need to have the pad dryer than that? hmmm

Also regarding the cover, do you recommend stretchy jersey fabric, like from a t-shirt, or non-stretchy fabric from a bedsheet or regular shirt? Is there much difference there? I've been using non-stretch but not for any scientific reason...

FWIW, I have had mixed results with walnut oil. Both very good and troublesome. Hence, I returned to olive oil and am presently pleased. I find I can keep the pad more well lubricated with olive oil.

JonWint · #8 02-03-2017, 11:54 AM

Quote:

Originally Posted by davegardner0

It's possible I have too much Shellac in the pad...I've been pretty much adding equal parts 2lb cut shellac and ethanol. Maybe now that I'm building a good gloss I need to tone down the shellac?

You might have too much ethanol. I add shellac:ethanol between 4:1 to 6:1. Too much ethanol will soften the surface and start removing shellac. After sanding with 800 grit, it should only require one or two shellac passes to return the full shine. When I start a session, I add ethanol to the pad and then just shellac for the first few passes, only adding ethanol in the above proportion as the initial charging evaporates.

Caution, my experience is only 6 guitars deep.

funkymonk#9 · #9 02-03-2017, 12:41 PM

I don't know if the stretchy or tight fabric makes a difference but have always used soft hopefully lint free old t-shirt material.

I typically just dab a small fingertip of olive oil to the pad of 7-8 drops of shellac and 4-5 of alcohol. And like you said press the pad on paper until you get a spotty imprint.

I would look for some old thin soft t-shirt material, sometimes you get get it in a bag at a hardware store, sometimes it frays sometimes not so definitely look for lint free. Good Luck

Frank Ford · #10 02-03-2017, 12:44 PM

Just like getting great tone from a guitar, French polishing is all about technique and practice. Lots of practice.

Years ago, when I decided to get serious about it, I set myself up with a little fishing tackle box in which I had small bottles of the logical liquids, rags, etc. Every day I'd take the box out and work on an old banjo resonator, mandolin body, guitar top, or whatever - for five to ten minutes. Believe it or not, I kept up that regimen nearly five days a week for about a year.

I took a while to reach various plateaus, just as it does in learning to play. Sensing whether the mix is too thick or thin, whether it is going from pad to surface, keeping the build even, filling defects and pores, assuring good adhesion to old finish, working in cold or hot air - all those things came with time.

These days my favorite oil is Grumbacher's Pale Drying Oil, a very light bodied linseed with a bit Japan drier (I think) added.

I use oil in the smallest amount needed to keep the pad from dragging, so there's always a pronounced trail of evaporation as the pad moves.

I've used methanol and ethanol, but regular denatured alcohol is fine for me, and I try to mix shellac fairly fresh, so my liquid stuff isn't more than a couple months old.

redir · #11 02-03-2017, 01:02 PM

Quote:

Originally Posted by Ned Milburn

FWIW, I have had mixed results with walnut oil. Both very good and troublesome. Hence, I returned to olive oil and am presently pleased. I find I can keep the pad more well lubricated with olive oil.

Me too. I heard how great walnut oil was so I went and got some and was like... Really? Good old olive oil for me, the expensive walnut oil goes on the salad.

OP your cover is obviously the problem, use an old tee-shirt or something different. I use gauze padding material for the core.

davegardner0 · #12 02-03-2017, 02:26 PM

Quote:

Originally Posted by Ned Milburn

FWIW, I have had mixed results with walnut oil. Both very good and troublesome. Hence, I returned to olive oil and am presently pleased. I find I can keep the pad more well lubricated with olive oil.

This is a great tip, I'll try olive oil and let you know how it goes. Thanks!

Frank Ford · #13 02-03-2017, 04:15 PM

For a non-linty pad (or if you're being pedantic, "fad") cover, my fave is microfiber - I just use one of the guitar polishing cloths and it works very well.

In the "old days," the best polisher around these parts used well worn bed sheets, addiing a nylon stocking to cover the pad for spiriting-off, followed by really vigorous rubbing with his bare hand to get a mirror gloss. The hand rubbing really brings up the shine. I do that bit too, but find I don't need to use the stocking cover with the microfiber cover.