Traditionally tray development requires shorter processing times, this is for convenience and also to minimise the risk of aerial fogging, and uneven staining. So this is why it's used with more alkali & bromide and slightly more concentrated.
People using Pyrocat today un trays often use the 2+2+100 dilution rather tahn the 1+1+100 for similar reasons.
The Metabisulphite needs to be added first to prevent oxidation of the Pyrogallol which decomposes rapidly in water without it. It's important to use reasonably fresh Metabisulphite as this increases the potential shlf life of Part A.
The Ilford published formula uses 37.5g Sodium Carbonate (anhydrous)
Last edited by Ian Grant; 05-11-2010 at 07:02 AM. Click to view previous post history.