DMax of different papers

Fatih Ayoglu · Aug 5, 2024

Hi all,

I’m not quite sure if I’m doing something wrong but have an interesting (at least to me) issue.

In the exact developer, at the exact time, which is Ilford MG 1+14, I can get 2.1 DMax with Ilford RC Pearl but only 1.5 DMax with Ilford FB Matt.

I have tested this issue with a strip sheet, cut 0.5” and exposed to a light bulb which is 800lumen and then even during development, I’ve left the light on so the paper is exposed really long to make sure.

I understand Pearl paper is shinier than Matt paper but is this difference expected?

Many thanks,
Fatih

RalphLambrecht · Aug 5, 2024

Fatih Ayoglu said:
Hi all,

I’m not quite sure if I’m doing something wrong but have an interesting (at least to me) issue.

In the exact developer, at the exact time, which is Ilford MG 1+14, I can get 2.1 DMax with Ilford RC Pearl but only 1.5 DMax with Ilford FB Matt.

I have tested this issue with a strip sheet, cut 0.5” and exposed to a light bulb which is 800lumen and then even during development, I’ve left the light on so the paper is exposed really long to make sure.

I understand Pearl paper is shinier than Matt paper but is this difference expected?

Many thanks,
Fatih

very much expected. The highest Dmax will be with a glossy surface. But please don't worry. A Dmax of 2.1–2.15 is plenty to make a perfect print, and Ilford darkroom papers will give you that. Interestingly enough, inkjet papers typically have a higher Dmax. I've seen up to 2.5.

xkaes · Aug 5, 2024

Every paper is different -- even if developed exactly the same way. And if they are developed differently, the differences can be even more different. That's one of the reasons why some people prefer one paper over another.

You can figure it out for yourself -- as you have been. Congratulations. Richard Henry explains it all is his book, "Controls in B&W Photography".

RalphLambrecht · Aug 6, 2024

xkaes said:
Every paper is different -- even if developed exactly the same way. And if they are developed differently, the differences can be even more different. That's one of the reasons why some people prefer one paper over another.

You can figure it out for yourself -- as you have been. Congratulations. Richard Henry explains it all is his book, "Controls in B&W Photography".

a wonderful book; unfortunately out of print for years, but I managed to buy it from my local library for $$$.

koraks · Aug 6, 2024

Fatih Ayoglu said:
I can get 2.1 DMax with Ilford RC Pearl but only 1.5 DMax with Ilford FB Matt.

* Matte paper creates lower reflected dmax by default. The practical limit is around 2.3logD for glossy paper, while matte paper generally tops out at maybe 1.7-1.8logD or so.
* FB generally requires longer development than RC. However, given the dmax limit of matte paper and the 1.5logD you arrived at, you appear to be developing sufficiently.

Fatih Ayoglu said:
exposed to a light bulb which is 800lumen and then even during development, I’ve left the light on so the paper is exposed really long

Note that the H/D curve of a silver halide emulsion tapers off after its peak - it effectively starts to reverse. To hit dmax, you need to expose just long enough to get there, but not more.

Fatih Ayoglu · Aug 6, 2024

Thank you all for your kind replies.

@koraks yes I develop FB paper for 5 minutes and RC paper for 1,5 minutes as described in the Ilford document. I wasn’t aware of the fact that the paper requires just enough exposure to reach maximum black, something probably we don’t realise when using enlarger as we print when we see enough blacks.

It’s not that I’m unhappy with lower DMax, the other day I wanted to measure with a densitometer and have realised the difference and then thought maybe I’m doing something wrong

Keith Tapscott. · Aug 6, 2024

Fatih Ayoglu said:
Hi all,

In the exact developer, at the exact time, which is Ilford MG 1+14,

Many thanks,
Fatih

A stronger dilution would help. Try 1+9.
Glossy papers will provide deeper blacks than Matt surfaces. Also you could try selenium toner.

RalphLambrecht · Aug 6, 2024

koraks said:
* Matte paper creates lower reflected dmax by default. The practical limit is around 2.3logD for glossy paper, while matte paper generally tops out at maybe 1.7-1.8logD or so.
* FB generally requires longer development than RC. However, given the dmax limit of matte paper and the 1.5logD you arrived at, you appear to be developing sufficiently.

Note that the H/D curve of a silver halide emulsion tapers off after its peak - it effectively starts to reverse. To hit dmax, you need to expose just long enough to get there, but not more.

a really good point!

DMax of different papers

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