pyrocat m as a two bath.

[el wacho]

hello,

i have been experimenting with the longetivity of bath A (described as follows )

bath A

Cachetol 5g
metol 1g
sodium metabisulfite 10g
water 1000ml


now, i have extended the life for two weeks with no noticable difference in development.

another interesting thing i noticed was that tanning ( in particular, the engraving - etching effect you see on the emulsion ) seems to be alkalinity dependant. for the first bath b i used sodium carbonate 36g/1000ml water and there wasn't any noticable tanning but when i switched to sodium hydroxide 12g/1000ml it was obviously there. there was also the expected increase in grain and on both examples there was no apparent stain. the test prints print nice enough but not enough to depart from my usual 1:1:200 single bath practise.

any insights or suggestions welcomed.

 

[sanking]

Very interesting work.

Pyrocatechin is very sensitive to sulfite and a slight excess will kill the stain. Increasing the amount of sodium metabisulfite to 10 grams per liter of working preserves the solution, but kills the stain.

The excess of sulfite may also be responsible, at least in part, for the lack of tanning action.

Sandy King

hello,

i have been experimenting with the longetivity of bath A (described as follows )

bath A

Cachetol 5g
metol 1g
sodium metabisulfite 10g
water 1000ml


now, i have extended the life for two weeks with no noticable difference in development.

another interesting thing i noticed was that tanning ( in particular, the engraving - etching effect you see on the emulsion ) seems to be alkalinity dependant. for the first bath b i used sodium carbonate 36g/1000ml water and there wasn't any noticable tanning but when i switched to sodium hydroxide 12g/1000ml it was obviously there. there was also the expected increase in grain and on both examples there was no apparent stain. the test prints print nice enough but not enough to depart from my usual 1:1:200 single bath practise.

any insights or suggestions welcomed.