DD-X at alternate dilutions (e.g. 1+6)

[bvy]

I want to do some tests with DD-X at dilutions higher than 1+4, which is the only one described in the Ilford literature. I'm looking for reasonable starting times. For HC-110 and some other developers, the math is easy -- dilute by half, double the time. So 5 minutes at 1+31 becomes 10 minutes at 1+63 -- and for an intermediate dilution, it would be 7.5 minutes at 1+47. So it's very linear.

With DD-X then, I might reasonably expect to double the 1+4 time to get a 1+9 time. But the 1+9 times at MDC (and anecdotal stuff found elsewhere) suggest backing off from a full doubling. To complicate things more, different films have different times at 1+9, so there's no consistent "multiplier" that can be deduced. The 1+9 times seem to be between 1.5 and 1.8 times the 1+4 times.

I actually want to use DD-X somewhere in between -- at 1+6 or 1+7. If, for a given film, I can find a 1+9 time that I can trust, can I assume a linear relationship to arrive at times for these intermediate dilutions?

 

[bvy]

For example, ADOX CHS 100 (whatever that is) has a 1+4 time of 7 minutes, and a 1+9 time of 13 minutes -- not quite twice the amount of time (what I would expect). Other films follow suit: Acros has 9 and 16 minutes, HP5+ 9 and 15.75 minutes, TMY 8 and 14.5 minutes. These times are from the MDC at digitaltruth.com. The times are all around 1.75 to 1.8 times the 1+4 time. Is there something unique about DD-X?

 

[faberryman]

Why do you want to use higher dilutions? Surely this is not just a cost savings measure.

 

[bvy]

Why do you want to use higher dilutions? Surely this is not just a cost savings measure.

My question was separate of my motives, but yes -- partly to economize because I store the stock in 60ml bottles and use it one shot. 60ml is the minimum amount of stock required for one roll of 35mm or 120. I don't want to keep partial bottles, and I don't want to use two 60ml bottles (twice the needed amount) for one roll of 120. (60ml of stock at 1+4 won't cover a 120 reel.) DD-X isn't the cheapest developer out there and it's only available in one small size.

Also, I want to get the benefits of higher acutance and slightly reduced contrast. I find DD-X very contrasty at 1+4.

 

[pentaxuser]

Bvy, your reasons seem perfectly valid to me but while there is mention in the instruction sheets of re-using DDX with a slight reduction in quality, I cannot see any way to work out what that might translate into in terms of times with one shot but at 1+9.

It might be worth an e-mail to Ilford. Based on extra films you can develop with the re-use method it would seem that there is little chance that 1+9 dilutes DDX strength to below the minimum of stock required.

A member on a U.K. site called FADU( film and darkroom user) asked Ilford about substituting DD for DDX and got the reply that essentially it was one and the same material. DD comes in a 5L quantity and is quite a bit cheaper here in the U.K. Whether using DD at 1+4 is as cheap as 1+9 DDX I haven't worked out and if it is the same stuff then that still leaves you with your contrast problem.

pentaxuser

 

[faberryman]

Also, I want to get the benefits of higher acutance and slightly reduced contrast. I find DD-X very contrasty at 1+4.

Generally one deals with contrast by reducing agitation or development time.