Tony,

Yes I recall doing the beetroot experiment when I was a child.

I read about using Turmeric as an indicator for Boron. I tried making up some paper with it... I got no visible reddish colouration on drying after exposure to boric acid or borax. Got a speckle of light blue coloured bits after re-moistening with NaOH solution, but it was still mostly yellow.

Maybe I prepared the paper improperly? I used warm methanol to extract the turmeric, filtered and applied to bleached coffee filter paper, then air dried. Maybe that extracts other yellowish compounds that do not react with Boron? Hopefully it wasn't the paper!

Regards,

Alan

You can also use beetroot pigment, which has quite an interesting heterocyclic structure (to an Organic Chemist). It fades with alkali, goes red again with acid. Turmeric (curry powder) also has indicator action.