TD-16 Developer Question

gone · Feb 4, 2014

I bought some TD-16 developer. Do I have to wait a day before using it like D76, or can it be used right away (within a few hours anyway)? Thanks.

Pat Erson · Feb 4, 2014

I always thought the "24 hrs rule" applied to D-76...

gone · Feb 4, 2014

I might just let it sit overnight to let things settle down. No harm to it I suppose. It will be nice to get some consistency and shelf life to my stock solution, so I have hopes for the TD-16.

MattKing · Feb 4, 2014

D-76 will work immediately after mixing, but ...

It will work somewhat differently than it will work a day later (the activity changes).

So if you want repeatable consistency, you need to wait.

cliveh · Feb 4, 2014

MattKing said:
D-76 will work immediately after mixing, but ...

It will work somewhat differently than it will work a day later (the activity changes).

So if you want repeatable consistency, you need to wait.

But isn't Michael correct, as long as the mixing temperature is correct it may be used immediately. What is this somewhat differently a day later?

MattKing · Feb 4, 2014

cliveh said:
But isn't Michael correct, as long as the mixing temperature is correct it may be used immediately. What is this somewhat differently a day later?

The activity of D-76 when first mixed is higher. If your negatives would be properly developed a day (or a week) later, they may be slightly over-developed if developed immediately after mixing.

The difference is real, but may not be particularly material unless you are developing materials where consistency is extremely important.

Or developing films commercially, where others are paying you for very repeatable results.

If you don't check your processing with step wedges/control strips and densitometers, you may have trouble noticing the difference.

Ian Grant · Feb 4, 2014

cliveh said:
But isn't Michael correct, as long as the mixing temperature is correct it may be used immediately. What is this somewhat differently a day later?

It can be used immediately but there's a drop in negative quality when you do.

Ian

Anon Ymous · Feb 4, 2014

cliveh said:
But isn't Michael correct, as long as the mixing temperature is correct it may be used immediately. What is this somewhat differently a day later?

IIRC, freshly mixed D76, even at the correct temperature, will be slightly more active, hence the one day or so waiting period.

cliveh · Feb 4, 2014

If D76 has been correctly mixed and I know this takes some time and then used at the correct temperature and dilution, why should it produce a different result at a slightly later date?

Rudeofus · Feb 4, 2014

cliveh said:
If D76 has been correctly mixed and I know this takes some time and then used at the correct temperature and dilution, why should it produce a different result at a slightly later date?

Because it may change pH over time, and have the biggest changes during the first 24 hours after which it reaches an equilibrium?

cliveh · Feb 4, 2014

Can PE please comment on this?

DREW WILEY · Feb 4, 2014

I routinely used 76 for many years to develop unsharp masks for color printing in the lab, so had opportunity to routinely measure what was
happening using a densitometer. The point is, that you want to standardize your procedure on either freshly mixed 76, or upon 76 which has
reached a plateau and stays there awhile. In other words, yeah, you can use it right away, but you'll get different results than using developer
which is, for example, anywhere from a couple days to six weeks old (store in full glass bottles).

DREW WILEY · Feb 4, 2014

Oh... back when I did try TD16, it seemed to behave just like 76 at equilibrium, not fresh-mixed.

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