Rollei RBM Black Magic 5 is a hardener additive for the Black Magic liquid emulsion system, 250 ml.
What it is for
The hardener strengthens the gelatin layer, and is needed exactly when that layer risks not surviving processing: warm solutions, long washing, a support the emulsion tends to lift from. Without it a coated layer can soften and slide off in the tray.
How to dilute it
Storage
Sealed concentrate keeps well but dislikes air: the emptier the bottle, the faster it oxidises. Decant the remainder into a smaller bottle, or displace the air — that is what gets a concentrate to its last measure.
How it compares
Another system consumable. At room temperature on a well-prepared support you can do without it, but on glass and metal it is what saves the coating.
