My cyanotype chemistry - a mystery occurs..

[gandolfi]

help!!

I don't get it!

when making my chemistry, I always make the raw chemicals in teo seperate containers (100ml in each)

When mising for use, I carefully use 1:1

But when I am getting to the end of the chemistry, there's always more - much more left in one of the bottles!!

and always in the ferriammoniumcitrate bottle...

Magic/mystery? or?

I can't explain it - can any of you?

 

[Vaughn]

Look at the amount/volume of Ferric Amm cirtrate you add compared to the Pot ferricyanide! It takes up a lot more space!

 

[Loris Medici]

Emil, how do you measure the solutions? (a.) Drop count (by pipette) or (b.) proper ml (by syringe)? If the former - (a.) that is... - mind that different solutions' specific gravity and surface tension are also different, therefore the drop volumes are different - hence the different rate of consumption... If the latter, I can't think of anything other than the phenomenon may be caused due to different vapor pressures (highly affects evaporation speed / rate) of the solutions. (But, most probably that can be omitted if you aren't using very large containers / small amounts of solutions and I highly suspect it would cause a significant difference...)

???

Regards,
Loris.

 

[Zewrak]

Nah, I have to go with magic.

 

[gandolfi]

Look at the amount/volume of Ferric Amm cirtrate you add compared to the Pot ferricyanide! It takes up a lot more space!

yes - but I first dilute the Pot ferricyanide in about 50ml water - and then when dissolved I add water to 100ml... so there's the same ml in both bottles.

 

[gandolfi]

Emil, how do you measure the solutions? (a.) Drop count (by pipette) or (b.) proper ml (by syringe)? If the former - (a.) that is... - mind that different solutions' specific gravity and surface tension are also different, therefore the drop volumes are different - hence the different rate of consumption... If the latter, I can't think of anything other than the phenomenon may be caused due to different vapor pressures (highly affects evaporation speed / rate) of the solutions. (But, most probably that can be omitted if you aren't using very large containers / small amounts of solutions and I highly suspect it would cause a significant difference...)

???

Regards,
Loris.

I use a small mesuring beaker/glass (I think it is the name).
So I could just be unprecise, but why be that on the same chemistry every time.....

I thank you for your ideas - it might make sense - I have to think that over..

Question: Am I the only one experiencing this?

 

[Loris Medici]

Emil,

You can't be absolutely sure unless you're using identical syringes... (What about the beakers - Are you sure they're absolutely identical?) I completely switched to syringes myself, I don't measure with pipettes anymore. Beakers (to me) are fine for relatively large mixtures. (Few hundred ml and such...)

About "Why always the same solution?": The (A) ammonium iron(III) citrate solution is quite different (in terms of specific gravity and surface tension) from the (B) potassium ferricyanide solution, and maybe this is causing you to always slightly err towards less for A, and more for B !??? At least that shows YOU are pretty consistent! Which is something good in my eyes...

Regards,
Loris.

I use a small mesuring beaker/glass (I think it is the name).
So I could just be unprecise, but why be that on the same chemistry every time.....
...

 

[Worker 11811]

Are you measuring solutions in two separate beakers and pouring them together into a third or are you measuring 100 ml. of the first solution into a beaker then filling with the second solution up to 200 ml.?

Try this experiment: Get some 90% isopropyl alcohol (from the drug store) and measure 50 ml. into a beaker or graduate. Next, using a second container, measure out 50 ml. of plain water. Pour them together. Note the volume of the combined solutions.

You would expect the volume to be 100 ml. but it's not. It will be less.

The reason is because the molecules of water and alcohol are different sized. The molecules of alcohol slip into the spaces between the water molecules. It's similar to what would happen if you poured a bucket full of sand into a bucket full of marbles. The total volume will be less because the sand is going between the marbles.

The answer would be to measure two solutions separately and pour them together into a third container.

 

[Photo Engineer]

You guys ever hear of density?

Whenever you mix up a solution of ANYTHING, the density changes from 1.0 (water at 20 deg C roughly) to something else that may be lower or greater than 1.0. That is why in exact photographic work, we measure things by weight or use solutions made to a volumetric standard. In other words, you do not add 100 ml of water, you dilute to 100 ml with water, or you dilute to 100 g total with water, using whatever method applies.

PE

 

[Loris Medici]

Randy, bullseye! I just noticed the nuance: Emil writes about *THE* beaker, whereas I write about identical syringe*S*, identical beaker*S*... Knowing about the fact you describe, I never did it the other way around! (Combining different solutions by pouring them on top of each other, watching the intermediate/final volume, that is...) I always use the same number of measuring vessels as the the number of different solutions the job needs...

Regards,
Loris.

 

[Worker 11811]

They taught that to us in eighth grade chemistry class. That was back in the days when they still taught actual chemistry in schools.

While all the other kids were mixing alcohol and water together to learn about measuring volumes, I was mixing ammonia with iodine crystals and making the teacher's desk explode.

Gee... Maybe that's the reason they don't teach chemistry anymore?

 

[Vaughn]

You guys ever hear of density?

Whenever you mix up a solution of ANYTHING, the density changes from 1.0 (water at 20 deg C roughly) to something else that may be lower or greater than 1.0. That is why in exact photographic work, we measure things by weight or use solutions made to a volumetric standard. In other words, you do not add 100 ml of water, you dilute to 100 ml with water, or you dilute to 100 g total with water, using whatever method applies.

PE

Thanks...that makes sense. But just about all the formulas I have read for cyanotypes instruct one to add (for example) 100ml of water, not add water to make 100ml of solution. Or as in Hershel's original formula, "Ammonio-citrate of iron -- 20 parts, water -- 100 parts" (as per an article on unblinkingeye.com).

 

[Photo Engineer]

A formula is a formula especially if it works. Just expect to have uneven amounts of you do it the way you describe.

If it works, use it but expect what is observed in the OP.

PE

 

[gandolfi]

... In other words, you do not add 100 ml of water, you dilute to 100 ml with water, or you dilute to 100 g total with water, using whatever method applies.

PE

thanks - and that is what I do..... (dilute to)

I think I might be even worse in explaining than in doing....

 

[gandolfi]

Are you measuring solutions in two separate beakers and pouring them together into a third or are you measuring 100 ml. of the first solution into a beaker then filling with the second solution up to 200 ml.?

Try this experiment: Get some 90% isopropyl alcohol (from the drug store) and measure 50 ml. into a beaker or graduate. Next, using a second container, measure out 50 ml. of plain water. Pour them together. Note the volume of the combined solutions.

You would expect the volume to be 100 ml. but it's not. It will be less.

The reason is because the molecules of water and alcohol are different sized. The molecules of alcohol slip into the spaces between the water molecules. It's similar to what would happen if you poured a bucket full of sand into a bucket full of marbles. The total volume will be less because the sand is going between the marbles.

The answer would be to measure two solutions separately and pour them together into a third container.

Randy - what I will do is to mix 1:1 in plain daylight and see if it makes 2.....

 

[anikin]

C'mon guys, it's the ferri snatchers. Everybody knows that!

 

[Vaughn]

Does mold growth in the Ferric Amm citrate add to the volume?...LOL!

 

[wildbillbugman]

Vaughn,
You are a Carbon Transfer Man. What are you doing messing around with cyanotypes? Is this a signe of encroaching senility? Its like Beethoven playing "Chopsticks" on the Kazoo.
Bill

 

[Vaughn]

Hey, Bill! Got to get the kids hooked, I mean, interested in alt processes with the easy stuff -- then hit the arteries with the harder stuff later!

Taken during a two-week session with high school students. The first week was making pinhole cameras (empty 250 sheet boxes of 8x10 photo-paper and using 8x10 litho film) and cyanotypes -- and the second week was 35mm film and silver gelatin prints.