Saturday 10 October 2009

French polish

A few people have asked if I could give a tutorial on how I apply french polish. But before I do that - I think a little explanation of why I use french polish is in order.

Wood clarity.
Of all the finishes available to me - french polish does the least damage to the overall color and clarity of the wood. Oil is a sure fire way to darken Rosewood to oblivion and all the color and vibrance that makes rosewood so stunning is killed. Oil also kills East Indian Rosewood, turning the vibrant purple and red tones into mud. Oil does not affect Honduran Rosewood as much, but it does darken it. I do use warmed double boiled linseed oil on boxwood and then a coat of paste wax. For some reason - that finish seems a perfect “fit” for boxwood - and the darkening is not a bad thing.

French polish will wear with use - and I don’t mind that because as your hand rubs the finish, it will burnish the remaining french polish and wood to a similar luster. It is also a welcome part of the planes patina - its story if you will.

French polish is also a very pleasing tactile finish, it has a bit of a sheen to it, but not a plasticized look.

Not to mention it is a fairly safe finish.

Ok. On with the show.

I sand all the infill pieces to 600 grit. I start at 220, then 320, 400 and finish with 600 grit. A fellow planemaker once suggested the reason I use french polish was to avoid having to be particular about sanding. I just said “hmmm”. The above photo shows the inside surface of the front bun without finish applied.

Here is the kit. The white(ish) piece on the bench is foamcore which I use to test the mixture of the french polish and the mineral oil. I used foamcore because the surface is very smooth and not absorbent... and it was lying around from my design days. The shellac in the mason jar is a 2lb cut - roughly. I mix my own shellac using super blond flakes. I write the date of mixture on the top of the jar and a few months in, will add a splash of shellac thinner to compensate for evaporation. The film canister holds the rubber and the clear bottle with the white lid is drugstore mineral oil.

The rubber is made up of two pieces of cloth. The piece on the left is a 2-1/2" square of 100% cotton bedsheet (no really - it is an old bedsheet). The other piece is some other cheesecloth like fabric... but it is not cheese cloth.

I fold the cotton into thirds and then thirds again, place it along a center line of the “cheese cloth”, fold the cheese cloth down, then each side over. This is the rubber. It is flat for a reason - it lets you get into corners and is quite flexible and agile.

This is the grip I use. The section of the rubber at the tip of my thumb is held to the edge of the mason jar of shellac. I tip the jar until the shellac touches and charges the rubber. There is a small pool of mineral oil to the right of this brown spot. I touch my finger to the mineral oil and then transfer this drop to the rubber.

I place the rubber on this brown area (created over the last 8 years) and start circling it around. What I am looking for is a vapor trail. I want to see the alcohol flashing off just behind the rubber. It is kinda like the tail of a comet. When the trail is continuous as I go round and round - it is properly charged (at least for what I am using it for).

This is what a charged rubber looks like.

Very quickly, and with a fairly light touch, wipe the surface of the wood. There should be enough shellac and oil mixture to change the color of the entire surface of this front bun. You have to be quick and keep things moving - if you pause, the rubber will stick and will make a mess of things. As a point of reference - the inside of this bun should take about 10 seconds to apply a single coat.

Here is the surface after the first coat.

A few other points. I apply two coats a day - no more. This gives the shellac enough time to harden a bit and the next coat will not soften and remove too much of the previous coat. This process of softening the previous coat is what makes french polish so repairable. A little bit of the first coat is softened during the second coat and this is what allows french polish to build and fill the pores of the grain.

The flat profile of the rubber is what allows me to get into the corners on the front bun of a panel plane for example. The bun of a panel will take about 4 charges of the rubber - one for each side. After about the 6th or 7th coat, there is usually a little bit of oil on the surface of the infill so I don’t always need to put a drop of mineral oil on the rubber for the remaining coats.

Some woods like Ebony, African Blackwood and Honduran Rosewood build quite quickly because their pores are so small. East Indian rosewood take a bit more time. On average - I apply about a dozen coats to each plane.


Anonymous JeffB said...

Most accounts I have read on how to french polish recommend using olive oil and recommend against using other oils (including mineral oil) due to additives they might contain. Something about those additives possibly interfering with the finish. I guess that hasn't been your experience? Any specific reason for using mineral oil versus olive oil?

17 October 2009 at 15:02  
Blogger Konrad said...

Hi Jeff,

A good question. Joe Steiner taught me this method which he learned when he worked for a guitar maker “in his youth” (as he expresses it). I seem to recall Bob Flexner wrote about french polishing in Popular Woodworking a while back, and I am pretty sure he was using mineral oil as well. I have not had an issue with it (still using the original container of mineral oil). Maybe I got really lucky and chose one that did not have additives? I will look into it - thanks for the comment.


17 October 2009 at 15:07  
Blogger Cody said...

Wow, beautiful work Konrad. I tried to use french polish on pear years ago and had nothing but grief, I never managed to get a streak free finish. I'll have to re-visit it sometime.

I was thinking about you and Cory awhile back. I'm enrolled in an architecture program in Edmonton and have a design class that is oddly challenging. We spend most of our time drawing geometric shapes and objects using negative space, etc. It's so abstract and subjective, and sometimes the criticism from the instructor includes phrases such as 'it's not magical enough'. What the?

18 October 2009 at 11:03  
Blogger Konrad said...

Hi Cody,

It took me quite a few planes to get this process right... and I am not sure if it will translate into a furniture sized project... I suspect my rubber will be woefully inadequate (that is a curious sentence).

Are you doing critiques in your design course? I found that process to be the most challenging, but also the most valuable. The next time your instructor asks for something more “magical”, ask him or her for an example of what they consider magical. Seriously. If they are truly qualified to be teaching, they should be able to present you with an example of what they are talking about. And something that directly relates to the project at hand. If you are doing work with negative and positive space and he shows you a BMW 2002 as something magical... I would not call him or her qualified. This is one of the big challenges with design - articulating what exactly is “working” or ”not working” with a particular design. It is really easy to say this sucks, that is ugly... but being able to explain why within a design language is a whole different thing. And takes time to learn - but when you get there - it is really amazing.

Best of luck with it and I am sure you will look back on it in a few years very thankful for it.


18 October 2009 at 11:17  
Blogger David said...

Great post Konrad. Thank you for sharring your method of work! I don't know if you ever tryed a product sold by LV cald French Polish under the LV brand? I have to try the real stuff one day it alwayse facinated me but alwayse been scared to try!
Tahnk you again!

19 October 2009 at 18:48  
Anonymous Narayan said...


You do "magical" things with Brazilian Rosewood. Seriously, though, you do, and though I also like the boxwood pieces you've churned out, the Brazilian rosewood planes are still my favorite. Two of them in particular, in fact...

@Cody: part of the challenge in talking about design is finding language to articulate qualitative observations. And as Konrad says, don't be shy about asking a critic to tease out their language a bit and give examples. The exercise is important not just to get feedback on your designs, but also to give you the skills to talk about your designs and other designs.

19 October 2009 at 19:35  
Blogger Konrad said...

Hi David,

I have not tried the premixed(?) french polish from Lee Valley... although the super blond shellac flakes I use are from LV. French polishing planes certainly took some practice and I hope it will translate into success with french polishing furniture.


19 October 2009 at 20:25  
Blogger Konrad said...

Thanks Narayan. I think the magic is the Brazilian Rosewood... but I am happy to accept some responsibility for it.

Thanks for the additional advise for Cody. Cody - check out Narayans blog - and the photography in particular.


19 October 2009 at 20:34  
Anonymous Kerry said... use no pumice whatsoever, yes? And very, very little shellac, no alcohol only rubbers, no shellac-saturated rubbers to which "only three drops of a two pound cut is applied with the left hand, four drops of alcohol with the right, a sign of the Cross..." Interesting. Thanks.

9 November 2009 at 09:21  
Blogger JW said...

Hi Konrad,

I think you'll find that french polishing furniture isn't so hard. For sure, a larger rubber is needed, but the basics we learned at North Bennet are basically the same. I've used mineral oil regularly without issue. I also have tried raw linseed oil and been pretty happy with it. I do use pumice, too, but I also use a pumice/BLO paste to burnish and fill and burnish the surface before I start with the shellac.

The biggest part of the learning curve is developing a feel for the shellac, and it sounds like you have. (looks like it, too! Holy Cow!)

After a while I was laying in thicker base layers and basically forcing them to cooperate with a much thinner, but wetter, mix, and a more liberal use of oil. Final coats are just like you describe, but for more porous woods where I was more interested in filling the grain, I started with a thicker mix. I consider it a good "quick and dirty" method, and it helped me develop test pieces pretty quickly when I started messing with dyes and such, in conjuction with amber shellac.

More if you're curious...

Gorgeous floor, btw.


15 November 2009 at 11:56  

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