Dilution question to extend development time

[analog65]

I am testing my film and I have successfully determined N and N-1 and based on my calculations N-2 will be less than 5 minutes (which is not desirable).

My N and N-1 development is via D76 1:1.

If I further diluted one more ratio to 1:2 could I simply double my development time?

Thanks

 

[RobC]

no

 

[nworth]

You will have to experiment. Probably not double, but more dilution will extend the developing time. Try 1.4X to start.

 

[analog65]

Thank you!!

You will have to experiment. Probably not double, but more dilution will extend the developing time. Try 1.4X to start.

 

[ic-racer]

There was a big thread about dilutions and nomenclature. If 1:1 contains a total of two units and 1:2 contains three units then you are not cutting the concentration of developer in half.

 

[Mainecoonmaniac]

If you're trying to tame contrast by trying to reduce the density of your highlights on your negs, try stand development.

 

[analog65]

Excellent point!!! I suppose 1:4 would be 2x dilution of 1:1 then.

There was a big thread about dilutions and nomenclature. If 1:1 contains a total of two units and 1:2 contains three units then you are not cutting the concentration of developer in half.

 

[analog65]

not trying to do that. Trying to extend my development time beyond 5 min. thanks

If you're trying to tame contrast by trying to reduce the density of your highlights on your negs, try stand development.

 

[Mainecoonmaniac]

I do stand development on Arista edu

not trying to do that. Trying to extend my development time beyond 5 min. thanks

I use HC-110 1:100 for Arista EDU for 1 hour. That's beyond 5 minutes. Works for high contrast scenes. With stand development, the developer in the highlights exhaust first while shadows continue developing.

 

[Bill Burk]

not trying to do that. Trying to extend my development time beyond 5 min. thanks

I use D-76 1:1 and worked out times for TMAX 100 with 1:1 and straight. I haven't tried "more" dilute to get N-2.

I've decided for myself that the day I need N-2 I am going to use a different developer.

Michael R 1974 has been working on a very low contrast developer that might be ideal.

So to the generic advice to try stand developing... I'd add that it's possibly time to consider a compensating developer when you need N-2 or N-3.

And it would be a good idea to test and calibrate for that different developer, if possible including a speed test to ensure that you get the correct working exposure index.

 

[piu58]

> one more ratio to 1:2 could I simply double my development time?

developers without redox system react in such a way, Rodinal is an example: Double of the dilution, double of the time.

Most developers contain a second developping agent which regnerates the primary one. a typical example is metol and hydroquinone. If you double the dilution you don't half the concentration of metol because hydroquinone acts too. As a firts try use a time 30% longer if you half the concentration and 60% longer if you use only a third.

 

[gone]

I agree w/ Bill, it's probably your exposure if 1:1 isn't working, especially if you're running into development times of under 5 minutes at that dilution. My Tri-X negs look perfect at 7-8 minutes at full strength stock solution, so if you're getting under 5 minutes at 1:1, it's exposure or development temps. Most (nearly all) folks don't go beyond 1:3 w/ D76.

If it's not exposure or temps, you're using the wrong developer for your film, whatever it is. It would be helpful to know what film you're using. D76, while certainly a universal developer, is not for everything.

 

[analog65]

Hi, I am testing Ilford FP4+ with D76 1:1 in a Jobo CPP2 at 20C. I am using a Stouffer step wedge and verifying densities with a densitometer.

I have confirmed my personal EI is 100.

I have confirmed that N is 9 min, N+1 is 11 min and N+2 is 13m.

I am about to start testing for N-1 and N-2. I am going to expose some Stouffer step wedge negatives and test for N-1 and N-2 to round out my testing.

I will be developing a few sheets below my N time. My guess is that N-1 will most likely be about 7m and that puts N-2 below 5 min most likely.

This is the reason for my question.

My plan is to expose and test sheets at 8,7,6,5 min and check the densities and just see where things land. If it turns out that 5 min with D76 1:1 is not going to work, I wanted to have a plan to stay at 5 min or longer and I suspected that diluting to 1:3 would most likely get me the development time I need.

Here is the link to the FP4+ datasheet if needed. http://www.ilfordphoto.com/Webfiles/2006216115141521.pdf

Thanks

I agree w/ Bill, it's probably your exposure if 1:1 isn't working, especially if you're running into development times of under 5 minutes at that dilution. My Tri-X negs look perfect at 7-8 minutes at full strength stock solution, so if you're getting under 5 minutes at 1:1, it's exposure or development temps. Most (nearly all) folks don't go beyond 1:3 w/ D76.

If it's not exposure or temps, you're using the wrong developer for your film, whatever it is. It would be helpful to know what film you're using. D76, while certainly a universal developer, is not for everything.

 

[dburian]

Excellent point!!! I suppose 1:4 would be 2x dilution of 1:1 then.

To help you keep dilutions straight, consider using the + sign; x parts this + y parts that.
1+3 is a 25% solution (4 parts total) and that is half of a 1+1 (which is a 50% solution)
1+4 is a 20% solution



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[dburian]

To help you keep dilutions straight, consider using the + sign; x parts this + y parts that.
1+3 is a 25% solution (4 parts total) and that is half of a 1+1 (which is a 50% solution)
1+4 is a 20% solution



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Nope, 1+3 would be a 50% dilution of 1+1

1+1=2 total parts in the dilution
1 part dev/2 total parts= 0.5

1+3=4 total parts in the dilution
1 part dev/4 total parts =0.25

0.25 * 2 = 0.5

Or Half of 50% is 25%

1+4 is 5 total parts
1 part dev/5 total parts = 0.2
1+4 is a 20% solution

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[Anon Ymous]

I'm probably late, but here's the rule of thumb about D76 dilutions and the increase in development time. These figures can be extrapolated from published times for D76 at various dilutions. Let's assume we know the development time for stock solution D76 (1+0) and it is t.

The time for 1+1 dilution is ~ 1,4xt.
The time for 1+2 dilution is ~ 1,75xt.
The time for 1+3 dilution is ~ 2xt.

So, form 1+1 to 1+2 the time should be multiplied by 1,75/1,4=1,25.

The same multipliers can be used for Xtol too.