D-25 film developer

Description

D-23 with sodium bisulphite added: lower pH, finer grain still and a warmer negative. The developer for anyone who finds D-23 too contrasty.

What the bisulphite changes

It lowers the alkalinity and with it the rate of development. Times get longer, but grain gets finer and the highlight transition smoother still. Effective film speed drops a little in exchange — about a third of a stop.

What it is worth the time for

Big enlargements from 35 mm, soft portraiture, any subject where smoothness matters more than bite. If you want sharpness, take Rodinal — they are opposites.

Questions and answers

How does it differ from D-23?

Same formula plus bisulphite. Slower, finer grained, softer.