French Polish Problem.

[Peri]

So, I had a commission for a chess board.

I tried several finishes, but wasn't happy with any of them, so had a go at my first proper FP'd piece.

Totally happy with the result, no problem there.

I left the job for 4 or 5 days, things still looking great so I decided to give it a coat of clear bri-wax (tbh I'm not sure why, I wouldn't do it again....still).

Left the piece for another couple of days. Today I noticed a hairline fracture in the finish, looks like the maple square has shrunk by a gnats. It's hard to see, but you can feel it.

So I'd normally flat the whole top with some 1000 emery and put another coat of FP on - only now its got the wax on it.

Whats the best way to remove the wax? Do I have to resort to sanding everything back to bare wood?

I've got cellulose thinners, IPA, meths, turps substitute, acetone and white spirit - any of those help?

Thanks.

 

[Sgian Dubh]

Try white spirits, generously, perhaps scrubbing gently with either wire wool or fine nylon abrasive pads, and wipe off with clean cloth. Let dry and try the shellac again after the sanding you propose. You'll know pretty quickly if there's still a problem possibly requiring a full strip off. Slainte.

 

[profchris]

Dont forget that you can, at least in theory, FP just that part with the crack. Depends how easily the wax comes off, but if it dissolves and washes away with the white spirit that might be worth trying. New FP should meld in to the old invisibly, the hard part will be making that part level with the rest.

 

[mrpercysnodgrass]

I don't think another coat of shellac will fill the crack. I would fill the crack with a hard wax stick, rubbing the wax into the crack then levelling it off using the back of some old sandpaper. You can then put some more shellack on if it needs it.

 

[Peri]

It feels (although it's hard to be certain) as if the edges if the crack have risen slightly.

Am I correct in thinking that even if I fill and flatten the fracture perfectly, I'd still need to remove all the bri-wax before I go anywhere near it with a polishing rubber?

 

[Sgian Dubh]

It feels (although it's hard to be certain) as if the edges if the crack have risen slightly.
Am I correct in thinking that even if I fill and flatten the fracture perfectly, I'd still need to remove all the bri-wax before I go anywhere near it with a polishing rubber?

That lifting you describe suggests there may be a problem with adhesion of that piece of veneer. If so, it may be that you need to correct that problem by, for example, at minimum, feeding in additional adhesive and clamping. I could be wrong on the cause of the lifting you describe, but I've seen similar problems in the past where there are isolated pockets of poor adhesion under veneer. Anyway, if I'm right and you have to undertake some correctives to the veneer's adhesion it would mean more extensive repair work at least locally on the fixed pieces of veneer and on the polish, but you won't know how much until the repair work (if needed) is complete.

And yes, you should really remove as much wax as possible from the whole surface prior to undertaking any additional polishing. Shellac is remarkably tolerant of contaminants, such as dirt, grease, and so on, which is one reason for it being sort of universal base or barrier coat between problem wood surfaces and other film forming finishes, but it's best to try and avoid possible polish adhesion problems if possible. Slainte.

 

[Peri]

Thanks for your help Sgian.

It's not actually a veneer - its 1 3/4" thick solid wood.

I plan on doing a lot more French polishing, so I've just ordered some pure naphtha. I believe this is recommended for spiriting off. Any thoughts on the suitability of that as a wax remover?

 

[Sgian Dubh]

I'd not realised you were dealing with thicker pieces having simply assumed veneer, especially when you mentioned lifting. So, solutions might be, as mrpercysnodgrass suggests, a wax stick and repolish, or possibly sanding that area level and repairing the polish locally, followed by polishing the whole surface.

Yes, naphtha will act as a degreaser, but I'm not the best person to ask regarding French polishing technique: I've undertaken some French polishing, many years ago now that I think of it, but the main ways I've got shellac onto a wood surface has been with one of a brush, rag or a spray gun, the last one generally being my preferred method. I suspect profchris or mrpercysnodgrass can give you guidance you might need regarding French polishing techniques. Slainte.

 

[Peri]

It's difficult to explain. When I mentioned lifting it feels as if the very edges of the polish have raised slightly.

The fracture is so narrow it's hard to know if you're actually feeling a crack in the polish bordered by two hard edges (think of a road surface with a kerb running on either side), or if there's a minimal 'crack' with the polish very slightly pushed up over it.

 

[Ozi]

I'd go for the Indian Pale Ale, drink enough till you think da it'l be a reeght.

 

[Just4Fun]

I have limited experience with French Polishing so treat this with a pinch of salt, but ...

When you polished, did you use pumice? I understood that its main purpose was as an abrasive to smooth out the shelac but when I used it I believe it filled pores in the wood. I don't know if that is really true but if it is, would it be any good to fill the tiny crack in this piece? It seems the crack is too small to see properly but it can be felt so it should not take a lot to fill it.

Incidentally I also used wax over the top of shelac / French polishing. In my case it was for the top of a sort of lectern. I was happy with the combination, but I didn't have to go back and make any repairs like this. To be honest that never occured to me. I will be a bit wary of such a combination from now on.

 

[Peri]

I believe the main purpose of the pumice is to fill the pores in the wood.

The problem I have is that I can't apply any more polish to repair the flaw without first removing the wax - my question is, how best to remove the wax without too badly damaging the surface underneath.

 

[mrpercysnodgrass]

I think what has probably happened is you have a little bit of shrinkage on the one light (sycamore!) tile. The shrinkage is uneven giving you a bow shaped gap, it is possible you may get further shrinkage what with the pieces being solid. As I said before you could fill this gap and flat it off then perhaps give it another coat of wax. If you feel it needs more shellac then you will need to remove the wax already on there. Just use white spirit and wipe off with a soft cloth or kitchen paper towel. This should not damage the surface in any way but before adding more polish you will need to abrade the surface with some '0000' wire wool. In forty plus years of French polishing I have never heard of naphtha being used to spirit off! I just use meths!! that said on a small surface like a chess board I would generally polish without oil so there would be no need to spirit off.

 

[profchris]

I tend to pad on shellac rather than FP, as that works better for me. I level and polish up afterwards.

I've used pumice for pore filling. What the pumice does is to abrade the wash coat of shellac and the wood, and force the slurry into the pores. If you are sparing with the pumice, it goes clear once wetted.

So for your problem this is what I'd try:

1. Remove wax with White Spirit around that area.

2. Level the area with fine abrasive.

3. Sprinkle a very little pumice on and apply shellac with a rubber. Repeat a couple of times, allowing drying in between. This should fill the crack with a slurry of shellac.

4. Level the area again going to very fine grits (P1000 or better).

5. Apply thin final coat(s) using your FP technique.

Then look at the whole thing and see how well it blends in. If you can't get a repair which works cosmetically, I'd dewax the whole surface, level it without going back to the wood, and then apply a few coats of FP on top to restore the final appearance.

As I said, not something I've done much of, but I think it would work OK.

 

[Peri]

Thank you very much for the assistance folks. Without places like this I'd be lost

 

[Peri]

Well that was easy.

I feel like I've made a bit of a mountain out of that particular mole hill.

Not confident with getting a repair to blend in, I used white spirit and 4-0 wool to de-wax, flatted with 2000 emery, recoated with FP and it feels perfect. A (very) sharp eye might detect a slightly thicker dark edge to the tile, but not noticeable at all. Under a light the surface looks flawless - and all took less than an hour

Thank you all again.

 

[Exluthier]

I tend to pad on shellac rather than FP, as that works better for me. I level and polish up afterwards.

I've used pumice for pore filling. What the pumice does is to abrade the wash coat of shellac and the wood, and force the slurry into the pores. If you are sparing with the pumice, it goes clear once wetted.


I agree. Under shellac, french polish, or oil varnish*, pumice has a close enough refractive index to the varnish to be almost impossible to distinguish. The late David Rubio developed a ground silicate slurry, based on volcanic deposits (pumice, to you and me) which I still use, and which is applied to bare violin wood before varnishing. It is still commercially available (Kramer Pigments, via artists supplies companies) and is often labelled as 'Rubio Soup'. There is some titanium in it, and a little of some natural yellow colouring, and it disappears altogether under violin varnish. It is said to be what the violin makers of Cremona used to use as the secret to their varnishes, and the pumice that Rubio used was sourced from the same area.

*Plenty of violinists want french polish on top of their oil varnish, these days, and it doesn't affect the way in which the silicate just disappears.

 

[Jacob]

More wax polish will fill the gaps. Tell the client to wax polish it every now and then. It'd need it anyway as French Polish isn't that durable and if the board was used for a few rough chess games it'd get scratched.