How about a source for nitric acid?
I used FeCl3 and the yellow tint it leaves is very annoying.

Royston, try a search for Ferric Chloride, thats what its sold as. ;)

Ariel, Jewelry makers supplires sell nitric acid. {in the UK anyway.}

Spiral

Same here in the US (that is where I get mine) but if your order it, hazardous shipping charges apply.

maplin electronics sell it, you appear to have one in glastonbury. see www.maplin.co.uk, and attached extract from there.

FERRIC CHLORIDE
 

Thanks for the information Gentlemen. I will give this a try. If it works I will post photographs. If I c__k it up I will deny ever trying it !!

Royston

since it's fairly close by to you, you can drive to cheddar gorge, there are some nice holes along the road, some especially nice ones around the upper parking lot. throw any rejects deep in there and confuse the future tony robinsons and their time teams. after all, someone has to do it.