OK. I've read through the few brief posts on this topic on here, to no avail!

I'm interested in silver mirror toning a la this guide. Before I get going with my problem, I should say that I don't have a copy of Tim Rudman's toning book (and I'm not sure I'm really into toning yet... I've only tried thiourea sepia toning so can't really justify the expense... yet).

Being a Yorkshireman (and thus NOT inclined to show my wallet the light of day) I'd rather scratch-mix the chemistry for this, instead of buying something like the Halo Chrome kit that I've read about.

I have located some Hydroxylamine HCl in the back of a cupboard at work, but can't find the HA-SO4 for sale to the public anywhere in the UK. (Not possible to order it in to work for 'private use' either).

Not letting the unavailability of the proper reagent deter me (!!), I had a crack at it this evening following 'formula 1' on the website, substituting the HA-SO4 for HA-HCl.

It didn't work! The image redeveloped very quickly (<30 sec) as a normal B&W image - with no hint of a silver mirror nor even a metallic sheen!

I'm not totally sure I understand the underlying chemistry at the moment, so my questions are these: -

1. Can someone please outline the chemistry. My guess is that the NaOH provides the alkaline envt. for the metallic silver to form a 'mirror' and the ammonia prevents the formation of silver oxide, but beyond that, I'm not quite sure what the HA-HCl or HA-SO4 are doing.

2. Can these formulae be modified to work using HA-HCl instead of HA-SO4?
3. If the answer to 2 is 'no', can the HA-HCl be converted into the SO4 without too much hassle? (I work in a lab so have access to a reasonable arsenal of reagents and eqpt.)
4. Is the reaction that's occurring here (in any remote way) similar to the ammoniacal silver nitrate 'silver mirror' reactions that you do as a student - I seem to remember that slower was better when carrying out this rxn!

Really hope someone can help!