Reproduction ivory look hand grips

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Posted by Simon Johnson 2 on 14/10/2021 16:23:50:

I'm intrigued by the potato in vinigar method, any more information on it anyone?

Had a quick look in my Chemistry books, only one of which gives directions for Cellulose Acetate. It doesn't involve potatoes!

Problem with spuds is they contain a lot of impurities in addition to cellulose, so the first step is to get rid of them. I suggest boiling and mashing with dilute caustic soda to get rid of the starch and any oils or gums. The solid residue left after washing in cold water will be mostly Cellulose. It also needs to be dried.

Cellulose reacts with strong Acetic Acid to make the ester Cellulose Acetate but the reaction is slow and inefficient. For efficiency, my book suggests using a mix of Glacial Acetic Acid and Acetic Anhydride with a dash of concentrated Sulphuric Acid. The recommended source of Cellulose is Cotton Wool, which is almost completely pure.

0.5g Cotton Wool + 10ml Glacial Acetic Acid + 10ml Acetic Anhydride + 1ml conc Sulphuric Acid

This reaction is quick, clean and high yield, but the ester would have to be processed further with a plasticiser like dibutyl phthalate to make it look like Ivory.

I think mixing potato with vinegar would produce tiny quantities of Cellulose Acetate very slowly, but any ester will be thoroughly polluted with unreacted spud – a dirty wet mess. Purifying the ester is possible but expensive – it involves dissolving it in an Ammoniacal solution of Cupric Oxide, and then precipitating in a dilute acid.

Easier and cheaper to buy plastic that looks like Ivory than to make it yourself.

Dave

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