HC-110 developer dilutions?

[Daniel_Buck]

I have been using HC-110 'stock solution' with 'dilution B', 1 part solution and 7 parts water which works out to just over 4 1/4 minutes of development time on my Tri-X 320 (4x5 sheets)

I'm wanting to try out some longer development times, 4 minutes seems very short, and I would like to conserve on solution (because at the moment, I can only develop one negative at a time)

Is there a ratio for dilution amount to development time? For instance if I double the amount of water (or 1/2 the amount of solution) do I then simply double the amount of development time? or is it more complicated than that?

I have seen a few websites that have info regarding dilutions, but most of them seem to focus on the pure HC-110, not the stock solution that I use. I have also seen handy charts for adjusting development time for temperature, but not for dilutions.

And on another note, since currently I can only develop a single 4x5 sheet at a time, how bad would it be to re-use the mixed developer for a few sheets in a row? Or is it really best to just use the solution once and dump it?

Thanks for any info or experiences!

[C. D. Keth]

I have been using HC-110 'stock solution' with 'dilution B', 1 part solution and 7 parts water which works out to just over 4 1/4 minutes of development time on my Tri-X 320 (4x5 sheets)

I'm wanting to try out some longer development times, 4 minutes seems very short, and I would like to conserve on solution (because at the moment, I can only develop one negative at a time)

Is there a ratio for dilution amount to development time? For instance if I double the amount of water (or 1/2 the amount of solution) do I then simply double the amount of development time? or is it more complicated than that?

I have seen a few websites that have info regarding dilutions, but most of them seem to focus on the pure HC-110, not the stock solution that I use. I have also seen handy charts for adjusting development time for temperature, but not for dilutions.

And on another note, since currently I can only develop a single 4x5 sheet at a time, how bad would it be to re-use the mixed developer for a few sheets in a row? Or is it really best to just use the solution once and dump it?

Thanks for any info or experiences!

At that concentration you should be able to develop half-a dozen or so sheets. If you search, many companies give square-inch ratings for a given volume of developer. If you find those numbers, I find you should believe them quite conservatively, perhaps only do 80% of what they say is safe.

Edit: Found it! Check the heading "Capacity" It also gives several dilutions that may suit you.
http://www.kodak.com/global/en/profe.../j24/j24.jhtml

[Bruce Watson]

Is there a ratio for dilution amount to development time? For instance if I double the amount of water (or 1/2 the amount of solution) do I then simply double the amount of development time? or is it more complicated than that?

It's more complicated than that. Mostly, it depends on agitation.

For continuous agitation (rotary, like with a Jobo rotary processor) development time varies as the square root of dilution. For example, if your time in HC-110B is 5 minutes, your time in HC-110H (twice the dilution of B) is (5)(sqrt(2)) = 7 minutes.

But... for intermittent agitation (like with a small tank that you invert a couple of times every 30 seconds or every minute) it's longer. How much longer depends on how intermittent your agitation is. A good rule of thumb is to double the time if you double the dilution.

For stand and semi-stand agitation, all bets are off. You'll have to experiment and see what works best for you.

And this whole discussion points out why in the end you should consider doing some testing to discover your personal exposure index (EI) and your personal development times as explained in various Zone System (and other methods) texts. Process varies from person to person, therefore your process has to be calibrated, which is largely what the Zone System teaches.

[Louie Powell]

Daniel -

I'm not aware of any explicit formulas for adjusting processing time with dilution.

Reusing developer presents problems. After the developer has been reused, it is partially depleted. Yes, it may be possible to reuse it, but in most instances it is necessary to extend the development time to compensate for this partial exhaustion. Again, I don't know of any arbitrary formulas for how much more development is needed, and you would have to develop some guidelines by experimentation.

I'm very familiar with the fundamental problem of short development time with dilution B. I have taken to using dilution H to avoid the problem. Dilution H is dilution B with twice the standard amount of water (ie, 1:62 rather than 1:31). With dilution H, development time is roughly twice that of dilution B - I say roughly because in my case, N with dilution B is 6 minutes, or 11 minutes with dilution H (with Efke 100 sheets).

If you are only processing one sheet, a short development time is not all that bad. In fact, I rather like the 4 1/2 minute development time that is my standard for 35mm T-Max 400. But when you move to sheets in a tray, you need more time to allow for the inherent imprecision associated with the fact that you can always be sure that the first sheet going into the tray will be the first sheet coming out of the tray. That imprecision can result in perhaps a 30 second difference in developing time between sheets in one batch - 30 seconds is a noticeable difference in a 4 1/2 minute developing time, but it is effectively inconsequential if you double the base time.

Frankly, however, I also concluded that flipping sheets in an open tray was prone to too many problems, so I eventually opted to use a slosher. The result has been amazing consistency and no scratches.