Alter id68 (microphen) to produce less contrast??

[Lachlan Young]

If you are desperate to modify ID-68, changing the buffer to a carbonate one and restrainer to phenylmercaptotetrazole will take you along the research direction that got Ilford to Ilfosol 3.

 

[Augustus Caesar]

Add about 2 grammes of boric acid/litre.

 

[RalphLambrecht]

Add about 2 grammes of boric acid/litre.

that will, of course, do the trick in a counterproductive way.

 

[Augustus Caesar]

that will, of course, do the trick in a counterproductive way.

What do you mean? It will slow down the development slightly.

 

[Andrew O'Neill]

Boric Acid is acts as a restrainer, so I don't see why it would be counterproductive...

 

[Keith Tapscott.]

If ID68 is too active, simply change to a less active developer formula like Autophen or similar, or one of the MQ Borax types.

 

[RalphLambrecht]

Boric Acid is acts as a restrainer, so I don't see why it would be counterproductive...

it could change the PH enough to throw everything out of wack. Reducing development time seems to be the better approach.

 

[koraks]

it could change the PH enough to throw everything out of wack.

It will adjust pH down. Activity will be reduced. This is what OP is after, so this particular mode of 'out of whack' would be desirable here. There's nothing really that will topple over or go catastrophically wrong when reducing the pH by this limited degree. The main downside is that the reduction in activity may be difficult to predict, although I'm sure there's some tables or charts here and there showing the relationship between pH and developer activity for a PQ system.

Since ID68 is already a boric acid/borate buffer, adding more boric acid will simply set the pH to a slightly lower value. Given that it's a buffer system, the effect won't be dramatic. I plugged the numbers into Copilot and it comes up with a drop from ca. pH9.0 down to pH8.7, which seems plausible to me. This can/will still constitute a significant difference in activity. Copilot gives a tentative guess of a 15-30% reduction in developer activity, which again seems plausible to me.

Of course, the net effect is the same as simply developing ca. 20% shorter as OP was already doing, hence the earlier suggestions to that effect. The advantage of simply reducing development time is that it's an easy and intuitive change in the process that has the desired effect and can readily be scaled up or down as desired, without any risk of gross non-linearity due to a buffer system running out of steam, non-linear pH-activity relationships etc.

 

[Keith Tapscott.]

Reducing the borax as well would also help.
The only problem is if the OP is replenishing the developer, because the replenisher would also need to be modified.

 

[Raghu Kuvempunagar]

Why tinker with the composition of the developer when a test for exposure index and development time can solve the problem?

@moderators: u may want to merge this thread with a previous one:

Alter id68 (microphen) to produce less contrast??

hi all! shout out koraks (I think it was him) who put me on to microphen. I love the developer, but it's very contrasty. It's actually perfect contrast - but I'm interested in seeing if I can reduce contrast somehow. Is there some sort of chemical I can add/reduce in the id68/microphen...

www.photrio.com

 

[koraks]

@moderators: u may want to merge this thread with a previous one:

Thanks for the suggestion; it's done!