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Met a geezer, through work, back in the earlt '90s, who had made a career working for Leiner Gelatin in South Wales, flying out to buy huge piles of beef bones from India, to be processed into gelatin. Thier main (/most profitable) market was supplying camera film companies.
Met another geezer, in the early '00s, who had a business exporting unneeded industrial plant from the UK.
You've guessed it; the worst smelling equipment he ever dealt with was from the closed Leiner Gelatin plant in South Wales.
Good read for the analog photographers on the ADOX website - May I use film if I am a Vegan?