What's going on here with this French polish?

[mic-d]

I noticed for the last couple of weeks that these lines have been turning up in the top of my box - look a bit like geological fault lines. I filled the top with numerous coats of shellac, rubbered on. Not too worried, they don't seem to go the full way through nor is anything peeling, so I think a sand back is all that's required. But what are they and why did they form?

[JDarvall]

It maybe the way it went on.

The stuff drys so bloody quickly your technique has to be down pat I think. lines over lap.

probably could get it out with more shellac and fine steel wool. heaps of raking light.

[mic-d]

Thanks Jake.

[JDarvall]

no worries, but I'm no shellac expert. Theres probably a proper way of doing it.

Just expressing my thoughts since I've been trying it a bit too lately, and it doesn't exactly go on like oil eh. can't retouch the uneven parts the same way. I managed to get it out with recoats though..

[Horaldic]

I've had this happen on a table top. I thought I might have put just a portion of it on a bit thickly. Because french polish "goes off " very quickly if the layer is too thick it can form fissures as the solvent evaporates if there are thicker portions.

My French Polishing is by no means as expert as some here. What I tend to do is build up the finish with many very light coats. When I'm going to finish something I regard as important I practice my technique on something that doesn't matter so much to start with. As a result I have a few workshop items french polished, such as my chisel rack.

[ubeaut]

What shellac did you use?

Was it well mixed before application?

What is the timber?

Is the timber Kiln dried or part air dried?

Did you just use shellac from the beginning to the end of the job?

What else (if anything) did you use before, during or after the application?

Was it brushed, sprayed of french polished?

How many coats and what was done between the coats?

If french polished did you use an oil as a lubricant? If so what oil?

Where is the box stored, does it get sun on it or anything else that may put extremes of heat onto it?

[mic-d]

I've had this happen on a table top. I thought I might have put just a portion of it on a bit thickly. Because french polish "goes off " very quickly if the layer is too thick it can form fissures as the solvent evaporates if there are thicker portions.

My French Polishing is by no means as expert as some here. What I tend to do is build up the finish with many very light coats. When I'm going to finish something I regard as important I practice my technique on something that doesn't matter so much to start with. As a result I have a few workshop items french polished, such as my chisel rack.

I would say that is what happened except that it only turned up a number of weeks after I finished it:? This is a practice box too, so I'm not too worried, it's something to learn on.

Thanks for the q's Neil, answers are below...


What shellac did you use?

Was super blonde shellac from Jim at G&C

Was it well mixed before application?

Yes very well mixed and filtered too.

What is the timber?

NGR veneer over homemade plywood. Central core of the ply was old growth hoop, 6mm with 2 cross plies each side, hammer veneered. NGR was hammer veneered too. I'm guessing there was a few weeks between veneering and finishing, probably longer.

Is the timber Kiln dried or part air dried?
N/a
Did you just use shellac from the beginning to the end of the job?
yes
What else (if anything) did you use before, during or after the application?
nothing 'cept oil. see below.
Was it brushed, sprayed of french polished?
I used a rubber to apply
How many coats and what was done between the coats?
Too many to recall 40-50 maybe. Between coats I sanded lightly with 400g paper, not between every coat. I sanded to knock off any dust nibs but also to monitor how the filling was going. very open pored and also some big knife checks because it's bookmatched
If french polished did you use an oil as a lubricant? If so what oil?

During bodying in I used a tiny bit of extra virgin olive oil on the rubber. Just touched my fingertip in oil and then put a bit of it on the rubber. Just a very small amount. During spiriting off, I didn't use any oil and only redampened my rubber with a few drops of neat alcohol each cycle. Rubber was stored in a sealed bag between time.

Where is the box stored, does it get sun on it or anything else that may put extremes of heat onto it?
This is where it lives, just on the end of my bench, its been a pretty cool spot so far and no direct sun light. I only grain filled the lid because of its angle all the pores really stood out. The sides only received maybe 10 or so coats ad they don't present any problem.
It lives on the end of my bench because it's my chisel box, if you're wundrin:)



Thanks for all the replies.

[ubeaut]

OK What I see in the pic looks like the shellac is cracking up with movement of the timber as it appears in the main to be following the grain of the timber and not running across the grain (with the exception of the one in the top left corner which may just be reflection from a light).

Probably like a log cracking from the outside layers in towards the centre. Leave it long enough and it might crack right through to the timber.. The movement in the timber won't be apparent but what it does to the finish is. My guess is, it's as simple as that.

Super blond shellac is dewaxed and so it doesn't have the elasticity of regular waxy shellac and won't be inclined to move with the timber. If applied over a waxy shellac it will move at a different rate and could cause crazing or cracking.

It shouldn't delaminate.

Hope this is of some help.

Cheers :U

PS Just out of interest. This is why our Hard Shellac and Dewaxed White Shellac have an added plasticiser.

[mic-d]

Thanks Neil.
I reckon what you're seeing has to do with my carp photography skills. The cracks are pretty random, like mud cracking I guess. I think the flash is just highlighting all the cracks that run in one direction, but they go pretty well every which way.
Should I just sand back below them and try again? Anything you would do differently to what I described in my answers?

[ubeaut]

Yep think I just found the problem but not necessarily. Extra virgin olive oil not what I'd recommend and probably what has set up what sounds like crazing or at least the beginnings of it, if as you say it's a bit all over the place. Probably trapped in the finish and and anything below will not craze (crack) whilst that above will probably continue to.

Just an educated guess but I'm pretty sure that could be the problem. My preference of oil is paraffin, traditionally linseed was used but that tends to scum if you leave the job for a day or s without properly removing it. I find the paraffin as a non drying oil will yet you leave the job for a week or so and then basically, pick up where you left off.

I'm not a fan of other oils especially olive oil, grape seed, walnut and a couple of others that some tend to use.

Cheers - Neil :U

PS I'd probably be sanding with 600grit rather than 400 if needed.

[mic-d]

Thanks Neil, crazing, yep that is probably the word to describe it.

But I read about olive oil on the internet, or maybe I watched it on Youtube, so it must be right:;:D:D
I'll sand it back and use some paraffin oil next time.
See how it goes.

Cheers
Michael


Yep think I just found the problem but not necessarily. Extra virgin olive oil not what I'd recommend and probably what has set up what sounds like crazing or at least the beginnings of it, if as you say it's a bit all over the place. Probably trapped in the finish and and anything below will not craze (crack) whilst that above will probably continue to.

Just an educated guess but I'm pretty sure that could be the problem. My preference of oil is paraffin, traditionally linseed was used but that tends to scum if you leave the job for a day or s without properly removing it. I find the paraffin as a non drying oil will yet you leave the job for a week or so and then basically, pick up where you left off.

I'm not a fan of other oils especially olive oil, grape seed, walnut and a couple of others that some tend to use.

Cheers - Neil :U

PS I'd probably be sanding with 600grit rather than 400 if needed.

[eskimo]

to my way of thinking it looks as tho something under the polish has prevented it from filling/adhering ...much like oil does to water on a surface..but what?
not sure if olive oil, whilst taking into account the amount used, would cause the streaks one sees in the picture....one would'nt think that the marks (if olive oil) would go across the grain, considering that you rub with it?

is there the possibility something was splashed onto surface...but that doesnt look right either ..as i would have thought it would be more like droplet formations rather than lines?...but you never know

[mic-d]

I took my box across to a French polisher today and he immediately determined my problem as too much build. It seems you can have too much of a good thing. Anyhow, the remedy is still the same, sand back and redo it.:)

[JDarvall]

Glad you found the solution.

Not that I'd know much about shellac application but I didn't think it was crazing. Crazing seems moreso inside the finish. Like cracking glass. Yours looks something ontop. IMO. From as much as I can see here anyway.

A crazing pic I pinched from the net.

Have you ever tried ruby shellac ? ...... thought I'd try that one day.

[mic-d]

Hi Jake, I haven't used ruby shellac and I only know slightly more than zero about any shellac:D But the finisher I spoke to today had a 70l garbage bin full of ruby shellac buttons so I can say I've seen it:wink::D