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Notes on French polishing

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Blog entry by Beezle posted 06-03-2012 08:15 AM 1518 reads 10 times favorited 4 comments Add to Favorites Watch

Why French polish?

For about a third of the projects I do, there is usually one surface that I like to do what I call a “guitar” finish. That is, perfectly flat, clear and shiny. As in, how most guitars are finished. The hunt for chatoyancy .

And I have tried every path I could find to achieve that just short of spraying nc lacquer, which I am not going to bother with. The biggest disappointment for me has been water based “lacquer.” Not hard to work with. Used the best spray equipment I could find, tried several products, etc. and found a path to create the finish I wanted, but the mess that is spraying along with problems that always seem to crop up later as the finish slowly shrinks wasn’t working for me.

Then I decided to try French polish and even the finish on the first project came out wonderful and looks just as good here more than a year later.

The properties of the finish are fairly well known, but I believe it isn’t quite as delicate as its reputation would lead you to believe and it is absolutely the most beautiful finish I have ever seen.

I thought I would do a core dump of where I am in case it might benefit anyone else doing this and even hopefully attract some advice from others.

Instruction

I started out watching whatever Youtube videos I could find, those from Michael Thames being the most useful. Then I of course read the tutorial on the Milburn web site and that helped as well.

But I did notice that pretty much everyone does things a bit differently.

Then came the DVDs. First was Vijay Velji’s French Polish Like a Pro which I learned a lot from. My first project was done using more or less his technique.

But I had a lot of problems and kept looking and finally got to Ronald Louis Fernández’ dvd French Polishing for Guitarmakers 2.0. His advice in retrospect is what worked for me. I finally got the sense of time required to have control over the process. Highly recommended.

Shellac sources

Note I always use “super blonde” or platina shellac.

The first shellac I obtained was this from Woodworker’s Supply. What I didn’t realize was it is not de-waxed. Murky stuff. I tried letting it settle and after about three months it did. About a third of the container was taken up with solids which I guess were wax. Never really used it.

Then I ordered shellac from Stewart-MacDonald and did a few projects with it. Seems like good stuff to me. Dissolved overnight and never gave me any problems. Very light colored. Over douglas fir it really allowed the subtle coloring of the wood come through.

As I learned more I decided to try shellac from ShellacFinishes.com. Also seems like good stuff. Dissolved overnight, color is clear, but more orange than any other blonde shellac I’ve tried. In use color seems about the same as the others.

Recently I read a blog entry by Christopher Schwarz on BT & C Tiger Flakes from Tools for Working Wood.= and just had to order some. Big flakes. And wow, it dissolves in a few short hours. Was still a wee bit murky until the next day, but I was amazed at how different it behaved. I also would almost swear it hardens faster over the short term. While working with it.

All in all, pleased with all of the de-waxed shellac I’ve tried.

Solvents

Behkol. Not much else to say. If you are tempted to try denatured alcohol from the hardware store, get some and put an ounce in a glass container and just let it evaporate away. What’s left is what is left in your finish. No thanks.

Naptha is supposed to be usable on shellac and it seems to be, but the common naptha at the hardware store seems a bit crude to me. Leaves a little behind. I figure to try Behlen’s naptha at some point. Might be good for spiriting away oil or as a wet sanding lubricant.

Oil

I have been using paraffin oil from the start. Meant to be used for French polishing. Seems fine and I see no reason to have to smell baby oil. Obtained from Woodworker's Supply, though I will probably try Behlen’s version when that runs out.

Containers

Containers for the alcohol and dissolved shellac are handy and I’m fussy about such things because I was trained as a chemist. The best I’ve found so far are these 8 ounce bottles from Woodcraft. They do not leak and you decide how big to make the hole in the tip. I like them so much I bought 20 of them.

For oil, I use a Glu-Bot. They are very good for such things. Even for glue. Nice product.

Otherwise, I use glass jars for mixing shellac and storing pads. Usually canning type jars.

Cloth

For pad covers, I first used old t shirts and that does work pretty well, but the material is soft and relatively thick and as the pad gets a little gummy fibers are easily pulled into the finish. Plus, you tend to run out of old t shirts pretty quickly.

So I tried this cheesecloth from Woodworker’s Supply and it works pretty well. But the weave isn’t all that tight.

Then I heard about Mohawk's trace cloth. Smallest portion you can buy is a five pound box. Basically a lifetime supply. Luckily, it is wonderful stuff. Very tight weave, very clean.

For the inside of pads I bought this cheese cloth from Woodworker’s Supply. Seems like good stuff to me.

I have also tried raw wool and it does work well, but it was too fluffy and difficult to make a tight pad with. I need to try cut up wool yarn or something. But the gauze/cheesecloth above is working fine for me which is good because I bought a lot of it.

Technique

I won’t go into the whole process here, but I basically use a hybrid of the different things I’ve read. Mostly based on Fernández’ advice from his DVD. The biggest difference so far as I know from other is time. He suggests patience on the order of a few days between bodying sessions and weeks of curing before finishing up the process. I am not quite that patient but I do try. Again, I recommend his DVD. He really showed me the spirit of it if that makes any sense. Everyone else seems to think you can do a decent finish in days. I am going with it taking at least three weeks to have a stable, perfect result.

I tend to put on layers a few times a day for a few days, then wait something like a week and then level the surface using Mirka 1000 grit or higher solid disks on a Festool orbital sander or 3M wet sandpaper wrapped around rubber blocks (erasers). I have tried using water as a lubricant and if the shellac is fairly hard I see no problem but I just don’t trust it so I use oil. Personally I’ve not had any problems with oil. Seems like you just avoid it until the shellac is built up some.

I will level the surface twice or so on the way to the final result. Shellac has for me been extremely forgiving in that sanding away accidents and mistakes and nibs never has caused any sort of witness lines, etc.

Again, time matters. I have found it takes weeks for the shellac to completely cure and shrink. One reason I put a week within bodying is to allow the shellac to shrink somewhat so I can see where I stand with any surface features showing up at the top of the finish. No matter how perfectly you fill the grain and sand, some texture will survive as the shellac tightens and shrinks against the surface.

For the final rubbing out I use Menzerna polishes. The final rub being their Intensive polish. Target used to sell this stuff but doesn’t appear to anymore. You can find the Intensive polish on Amazon, etc. for use by car detailers. The rougher polish I don’t see online anymore. It does help to step up to the final.

I have used many polishes for finishing various things and I like this Menzerna stuff the best. Better than car polishes, 3M Perfect It, etc. Really effective stuff.

So far as pads go, I create pads that are a bit bigger than I’ve seen from guitar makers except Fernández but smaller than one would use for a large table for example. I tend to not use them for long. One problem I tend to have is they get gummy and sticky on the side, then I’ll see fibers being pulled into the finish. I do not know how to prevent that gumming. I’ve tried squeezing any excess out of the pad after a session, extra alcohol, etc. but it seems to happen anyway. Something I still need to work out. Good thing I have a five pound box of pad cloth.

The quality of the finishes I am seeing at this point are stable, clear, have depth and true chatoyancy and at any angle look like the wood was finished with molten glass. Like a lens into the wood. They take a lot of time and effort and I would guess won’t survive abuse very well, but for a moment they make an object of beauty and the people I give my projects to seem to love it.

Future

I am going to keep working on my technique of course and trying new things as I discover them but I also will be experimenting with various woods, and different finishes that start with shellac. For example, shellac with a urethane top coat. What are the limits there? Can the color and visual appeal of shellac survive that? Etc.



4 comments so far

View Tugboater78's profile

Tugboater78

1006 posts in 843 days


#1 posted 06-03-2012 10:08 AM

Thanks for a little insight, finishing is greek to me atm but its something i need to learn

-- Justin - the tugboat woodworker - " nothing changed me like the first shnick from a well sharpened, decent hand plane"

View waho6o9's profile (online now)

waho6o9

4910 posts in 1228 days


#2 posted 06-03-2012 02:11 PM

Thank you for the information on French polishing.

View SASmith               's profile

SASmith

1590 posts in 1638 days


#3 posted 06-03-2012 04:23 PM

Thanks for sharing your technique.

-- Scott Smith, Southern Illinois

View bobasaurus's profile

bobasaurus

1251 posts in 1835 days


#4 posted 06-03-2012 08:20 PM

Very useful information. I might follow your advise and try it out.

-- Allen, Colorado

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