Embarrassing: Explain 1:1:100 to a dumb person

NortheastPhotographic · Nov 30, 2019

I got a Pyrocat HD kit coming in for some sheet and roll film processing. I understand it calls for 1:1:100. So equal parts A & B to 100 parts water, ok. Wait. I don't get it.

Let's say I'm running 5 8x10 sheets in my Jobo Expert Drum. How many ML of A & B to how much water?

ic-racer · Nov 30, 2019

You would need to know how many ML of your Pyrocat HD concentrate is required per 80 sq in of film. Multiply that times 5 then times 100.

Tom Kershaw · Nov 30, 2019

Pyrocat-HD is a great developer, but is probably not one to make up to working solution at 9am for processing at 3pm. I had a few issues with "death" of the developer when left for a while.

Ian Grant · Nov 30, 2019

I prefer 1+1 to 100

I've used Pyrocta HD for 15+ years I add 1 par A to around 50 parts water, add the 1 part B then mix to the 100, In my case that's usually 10ml to 500m water then the 10ml Part B and make up to 1 litre

Ian

Andrew O'Neill · Nov 30, 2019

10ml A + 10ml B poured into 1000ml water...

Sirius Glass · Nov 30, 2019

First what is the minimum for the Expert Drum? My 3010 is 210ml and that would be 2.1ml : 2.1 ml : 210ml but that is hard to measure so I use 3ml : 3ml :300ml. The problem with the previous post is that 1 liter is hard for the motor so as advised by the Darkroom Doctor http://www.darkroomdoctor.com/ the max that I would use is 500ml, which would be 5ml : 5ml : 500ml.

Valerie · Nov 30, 2019

I fill to 100 ml, then add 1ml A, stir, and then add 1 ml B. Right or wrong, it works for me (except for that one time that I got distracted and forgot to add A or B. Note: water alone does NOT develop film! )

James Bleifus · Nov 30, 2019

Andrew O'Neill said:
10ml A + 10ml B poured into 1000ml water...

+1

Patrick Robert James · Nov 30, 2019

I do the same as Ian. Technically it is 1+1+98, but it is close enough and it won't matter. Keeps life simple too. I prefer to mix with the water as well, so the developer goes in the beaker first, then I pour water in. No stirring that way. Like I said, simple.

awty · Nov 30, 2019

How well do those big drum rollers work with pyrocat and 8 x10 sheet film?
Ive used tanks and smaller drums, but pretty much do each sheet individually in a tray now.

runswithsizzers · Nov 30, 2019

When discussing mixing ratios and dilutions, I see a lack of consistancy here and on other Photrio threads, and that can lead to confusion. The problem is, if I see instructions to mix chemical A with water at "1:9" it can be interpreted two different ways:
1. Add 1mL of A to 9ml water to make a total volume of 10 mL - OR -
2. Mix 1mL of A with enough water to make a total volume of 9 mL.

The first method is a ratio of part A to part B (water), and results in a 10% solution of A (by volume).

The second method is a ratio of part A to the whole, or a dilution, and results an 11.1 % solution of A by volume.

Andrew O'Neill (post #5) and Valerie (post #7) are using the first method (ratio of Part A to Part B). Ian Grant (post #4) is using the second method (concentration of Part A in Final Volume).

In the clinical laboratory where I worked for 22 years, everyone was trained to always express dilutions as a ratio of the part to the whole (method #2). But other labs may follow the the other method. No problems either way, as long as everybody understands which method is appropriate to get the correct results from your written procedures.

As a practical matter, for this particular dilution it probably does not matter. The difference between the concentration of 1mL of Part A in 100mL, total volume, is probably not significantly different from 1mL of A in 102ml total (I'm guessing). But other dilutions of other chemicals could result in significant differences if the wrong method is used.

GLS · Dec 1, 2019

Andrew O'Neill said:
10ml A + 10ml B poured into 1000ml water...

This is correct.

juan · Dec 1, 2019

Runs with sizzlers (damned iPad autocorrect) is technically correct, but as he or she says, it doesn’t matter with Pyrocat. It’s an effective developer at many concentrations. In his original articles Sandy King recommended a minimum of 50ml of 1:1:100 dilution for a 4x5 sheet. Be sure you use enough developer. And be consistent with the way you mix it. How someone else mixes probably doesn’t matter to you.

Vaughn · Dec 1, 2019

awty said:
How well do those big drum rollers work with pyrocat and 8 x10 sheet film?
Ive used tanks and smaller drums, but pretty much do each sheet individually in a tray now.

Has worked fine in the 3005 drums (PyrocatHD and Rollo is what I have used).

I mix the Part B in with the 1000ml water, then add the Part A right before I want to use it. Seems to work.

Kawaiithulhu · Dec 1, 2019

runswithsizzers said:
dilutions as a ratio of the part to the whole

Unfortunately, most photographic documents write with something more like "1:1:100" is actually 1+1+100 to make 102.
Which makes sense when seen in mixing stock into working solutions, the documents normally state "1:1" so 1+1 to make 2.
And in documents on making the stock solutions I most often see "add part B, then water to make 5L" style instructions to remove all doubt.

So confusing all the way around - BUT as long as the worker is consistent then results will always match their tests, which is the real goal.

Kawaiithulhu · Dec 1, 2019

awty said:
How well do those big drum rollers work

I've done my X-Ray film 8x10 experiments with (one sided film stock) stuffed into a drum on a Jobo and results never showed overt drag density, it would get very inefficient doing more than one sheet in a day because of having to clean+dry the drum for the next run...

runswithsizzers · Dec 1, 2019

Kawaiithulhu said:
Unfortunately, most photographic documents write with something more like "1:1:100" is actually 1+1+100 to make 102.
Which makes sense when seen in mixing stock into working solutions, the documents normally state "1:1" so 1+1 to make 2.
And in documents on making the stock solutions I most often see "add part B, then water to make 5L" style instructions to remove all doubt.

So confusing all the way around - BUT as long as the worker is consistent then results will always match their tests, which is the real goal.

Using the "+" sign rather than the ":" would eliminate much confusion. 1+1+100 is clearly different from 1+1+98. But 1:1:100 can be interpreted either way, as posts here prove.

The term "1:1" would be nonsense in the lab where I worked, and a 50% dilution would be written as 1:2. One advantage of expressing dilutions as the ratio of the-part-to-the-whole is when making multiple dilutions. If I make a 1:2 dilution of a 1:10 solution the dilution factors are obvious, and my final dilution is easily calculated as 1:20. But if using ratios of Part-A-to-Part-B, you would be making a 1:1 dilution of a 1:9 solution and your final dilution would be what?

Sirius Glass · Dec 2, 2019

Alessandro Serrao said:
That's 1 + 1 + 98 parts equal 100 parts total

NO. 1:1:100 means 1 unit added to 1 unit added to 100 units. 98 does not appear in the notation because it was not in the notation. If and only if the manufacture clearly stated 1 unit plus 1 unit and water to make 100 units would the amount of water be less than 100 units. Since it was not stated that way, your perception is just plain wrong.

Vaughn · Dec 2, 2019

As if I would notice any difference between 1+1 to 98 or 100 ml! Of course when dealing with 1:2 or 1:3, then it becomes a bit more critical! But as Kawaiithulhu said as he opened this can of worms, being consistent is the key...and being clear when communicating with others helps.

For sheet film, I mix my Ilford Universal PQ developer at 1:9...if I need a liter, that's 100ml added to 900 ml water. But I have used dilutions down to 1:19 as needed (50ml to 950ml).

runswithsizzers · Dec 2, 2019

Sirius Glass said:
NO. 1:1:100 means 1 unit added to 1 unit added to 100 units. 98 does not appear in the notation because it was not in the notation. If and only if the manufacture clearly stated 1 unit plus 1 unit and water to make 100 units would the amount of water be less than 100 units. Since it was not stated that way, your perception is just plain wrong.

The point I was trying to make in post #11 is that you can not assume that "1:1:100 means 1 unit added to 1 unit added to 100 units"

In the clinical lab where I worked as a medical technologist, if a procedure called for mixing a solution at 1:100, that always meant 1mL added to 99mL for a total volume of 100mL. As I said, other labs may be different.

In this specific case, I believe you are correct to say that Sandy King intended Pyrocat HD to be mixed 1+1+100 for a total volume of 102, because on <this webpage> titled "Mixing Pyrocat HD, he says:
"... a dilution of One Part A + One Part B + 100 Parts water..."

But to say the notation "1:1:100" should ALWAYS be interpreted that way is not entirely correct, because I know of at least one lab where that assumption would get you (and the patients of that hospital) in trouble.

The topic of using the colon symbol to express mixing solutions was discussed at length in <this thread> The consensus was that there is no consensus. Depends on how you were trained. Because of the ambiguity that goes with using the colon to express dilutions, I would advise everyone mixing chemicals to find out for sure what the author intended rather than making assumptions. And I would urge everyone writing procedures and recipes to avoid the use of the colon altogether and replace it with the plus symbol, or write out instructions that cannot be misinterpreted.

GLS · Dec 2, 2019

In chemistry, the colon is always used to express ratios in this context.

Therefore a 1:2 mixture of A:B means one part A to two parts B, NOT one part of A + one part B.

Sirius Glass · Dec 2, 2019

GLS said:
In chemistry, the colon is always used to express ratios in this context.

Therefore a 1:2 mixture of A:B means one part A to two parts B, NOT one part of A + one part B.

It is amazing that chemistry and its notation are so direct and clear and yet some truly ignorant people can really crap up the understanding for others.

Vaughn · Dec 2, 2019

When I am using film holders for 4x5 to 11x14, unexposed film is designated by the white/silver on the darkslide handles showing, and black when exposed. It is probably the most common method used -- 'as the film gets exposed it goes black' is how I remembered it. But it pays to check when working with someone to make sure we are both on the same page.

I pour my carbon tissue at a rate of 1.2ml per square inch, though I might go down to 1.0ml/sq in. Mixing measurement systems is even more fun than fooling with ratios!

James Bleifus · Dec 3, 2019

Sandy wrote this in an article about Pyrocat:

“For developing negatives intended for printing with silver gelatin papers the recommended working solution is a 1:1:100 dilution.

One Part Stock Solution A + One Part Sock Solution B + 100 parts water.”

https://www.sandykingphotography.com/resources/technical-writing/pyro-staining-developers

Cheers, James

Ian Grant · Dec 4, 2019

Sirius Glass said:
NO. 1:1:100 means 1 unit added to 1 unit added to 100 units. 98 does not appear in the notation because it was not in the notation. If and only if the manufacture clearly stated 1 unit plus 1 unit and water to make 100 units would the amount of water be less than 100 units. Since it was not stated that way, your perception is just plain wrong.

1:1:100 is exactly the same as 1 +1 +98 ie making up to 100 unless you're Kodak. Some companies used to put 1:10 (1+9) or 1:20 (1 +19) on their bottles for clarity. So you were agreeing with the poste before

Kodak use 1:3 to mean 1+3 = make up to 4 and is goes against the convention of the Dilution ratio that 1:3 means 1 part in a total of 3,

It's better to be clearer so I always say 1+1 to 100

Embarrassing: Explain 1:1:100 to a dumb person

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