Don't know so much about the "girders" but the recipe is still a Barr's family secret which is very closely guarded and is still made in Scotland.....interestingly the product was originally invented as a hangover cure and tastes different in cans and plastic bottles as it does to when it's stored in a 750ml glass bottle...don't know why it just does.
i'm sure i read somewhere (probably on here) that it contained some sort of iron or iron oxide pigment or whatever - hence made from grrrdrrrs as the scots say
It contains ferric ammonium citrate, a food additive for colouration I think. It stains like anything, as this chemical is a derivative of the rusted form of iron, which also leaves nasty stains
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Someone once told me that Scotland is the only country in the WORLD where a home-produced soft drink outsells the mighty Coca-Cola. I could believe it!