>
> Mac asks:
>
> >Perhaps you chemists out there could fill me in on how to tell whether my
> >>prints are clear.
>
> The chemical effect of 'clearing' by (meta)bisulphite is to reduce the
> yellow chromium(VI) of dichromate to chromium(III) which is blue-green and
> much paler by comparison. So the chromium is not removed by the clearing
> agent, just made less visible. It would seem better to wash it out if you
> can. It also seems to me likely that residual dichromate will be slowly
> reduced to chromium(III) by constituents of the paper anyway.
>
> Mike
Possibly any residual dichromate could be reduced by some pigments also -
with perhaps unwanted effects on the image? I used to wash until I thought I
had washed it out, then use a clearing bath, then wash this out. Was I just
obsessive?.
Peter Marshall
petermarshall@cix.compulink.co.uk