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From what I understand:
Dewaxed if used as a seal coat and a different finish is going on top. But what if the finish is all shellac? Some have said that waxed makes for a more flexible finish, but perhaps not as clear - is this true? I also read in a general wood finishing book that waxed is less resistant to moisture penetration but I don't know to what degree. Also will both forms adhere equally well to an epoxy pore fill? Thanks for the help.

The person whose brain you need to pick is Brian Howard, who participates in this forum. I think most people these days use dewaxed shellac only, but if the finish will just be shellac and nothing else, Brian thinks waxed is better. I'll stop typing about it, though, because I don't want to speak for him.

Waxed is the traditional way as it was done prior to the 1900's and it will adhere to anything just as it's de-waxed cousin. For my thoughts and process you can watch this video of me talking about my process and the reasoning behind it.
http://howardguitars.blogspot.com/2015/09/french-polish-finishing-traditional-way.html

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Brian, a question please. I bought some button Lac as an experiment. Once dissolved and settled out, about half seems to be wax.

I wiped on a couple of coats of newly mixed, ie before settling, and those were very reluctant to harden. I'm guessing the wax content was too high.

Am i right and if so do I just pour off and use the clear stuff and discard what settled? Or is my button Lac inferior stuff to be thrown away?

I just did my 1st FP with buttonlac. Far from pro, though - this is the 6th guitar I French polished.

All went well, I think. 1st couple of sessions and seal coat were with dewaxed shellac. Build and final sessions with button, used in the same manner as with dewaxed.

I put the shellac solution through a coffee filter, twice. That was it. It somehow seemed to need less oil in the mix, but maybe I am fooling myself.
The photo is the guitarvstill waiting for a final burnish session

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Hmm, had another look at the video, and it suggests my waxed shellac might dry soft unless I pummel it. Is that what I left out?

No, it should go hard without any pressure. That's why you can brush or spray the stuff on. Besides, how do you compress something that is pretty soft and is not contained within a vessel? What the pad does is to force the shellac into wood pores or the micro pits. It maintains a very thin coating because it's pretty difficult to put it on thick. It's possible but you'll be French polishing two months later. Most people get bored after a week or so. Thin coating means it dries and hardens much faster or sooner than spraying or brushing it on.
If half of your solution appeared to be wax I would say that is an extremely high wax content. Natural shellac has a content of around 5%. Maybe if you left it longer it would settle to a lot less than half. It certainly should be more like a quarter of the entire liquid, perhaps a bit less.
Try scratching a button to see how hard it is. That's what it should end up like once the shellac has been applied and it has been left to fully harden. I wouldn't try testing it's hardness until at least a month has passed. Test it on a very hard wood like ebony. Trying it on something like Walnut and Maple won't tell you much, the wood underneath just compresses.
Button lac lasts a mighty long time in it's dry state. I'd be surprised if it's beyond it's shelf life, unless you dewaxed it and it's been sat on a shelf for a few months.
Waxed shellac is a touch softer than dewaxed. Try polishing with the sediment of waxy shellac left at the bottom of a jar. You'll soon find out how soft that mixture is but that stuff is obviously a very high wax content.
The natural wax content (5%) might make it a bit more flexible, perhaps even tougher, although I've not found a method of testing that.

Michael, do you have an idea of how long will buttonlac last? For this guitar I ran out of recent dewaxed shellac. Went to the old box where I had some button, dewaxed lemon and Kusmi (? - the very dark one) shellac - they were lying around for 5 years or so. Lemmon would not dissolve (in fact it's still far from dissolved, 2 weeks later). Kusmi took a while but got there. Buttonlac dissolved overnight. Plus, I just love that color.

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member of the guild of professional dilettantes

Dewaxed I've had go off in a matter of a few years, although of course I've no idea how long it had been sat on the shelf at the retailers. The raw seedlac I've had now for 26 years and it still works perfectly well. I was given 3 Kg of the stuff by a violin maker so it's likely even older that 26 years. Button lac I've certainly had for around 12 years and it's worked fine. All the dry flake shellac I've had that has failed to dissolve has been dewaxed light coloured stuff - blonde.

Most likely stale shellac.....The buttons will keep longer than dewaxed flakes but will still go bad. They should be kept cool and dry and out of light when stored. My usual test to see if shellac is still good is to wipe a thin smear on a piece of paper and if it is not dry in 20 minutes I do not use the shellac.

Could also be your alcohol is not high enough proof or the denaturants are messing with the drying. I have seen both cause lack of hardening.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Pummeling toughen the coating by further polymerization through pressure. This will affect final durability but have nothing to do with drying or hardening.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Thanks Brian. The buttons were cheap via eBay as an experiment, so probably the lowest quality. Rather soft on the surface, though brittle inside. I may try again using a better source.

Yep they were stale....should be completely hard and crisp. Any softness or tackiness on the surface of the button and I toss em.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/