Cadmium Iodide

[Mark Kononczuk]

Does Cadmium Iodide increase tonal range on a collodion negative plate?
I am putting together an Old Workhorse recipe as suggested by Paul Barden who also suggested that collodion recipes don't really differ that much from each other in terms of end result. So, would adding Cadmium Iodide to Old Workhorse do anything? Maybe ruin it?

[paulbarden]

Does Cadmium Iodide increase tonal range on a collodion negative plate?
I am putting together an Old Workhorse recipe as suggested by Paul Barden who also suggested that collodion recipes don't really differ that much from each other in terms of end result. So, would adding Cadmium Iodide to Old Workhorse do anything? Maybe ruin it?

If you want to add Cadmium iodide to a collodion recipe, you can - but follow a proven recipe. The following is a Collodion specifically for making negatives and it uses four salts. But with four salts in this mix, it has a very short shelf life. Make only as much as you plan to use within 2 months. It ages quickly.

Part A: Iodizer
Into 100 ml of grain alcohol, dissolve (in order):
0.75 grams Cadmium bromide
0.75 grams Ammonium bromide
1.25 grams Cadmium iodide
1.25 grams Ammonium iodide

Part B: Collodion + ether
Measure 120 ml of plain collodion,
then add 50 ml of ether

When A and B are prepared, add part A into part B and mix well.

I did say that there is very little effective difference between the various collodion recipes, but with one exception: some are specifically for making positives and some for negatives. Those designed for specific uses are different enough from each other that they are not really interchangeable (not all-purpose). But most are usable for either use case.

[Mark Sawyer]

For making negatives, the developer is the variable. Mixing used developer in with the new will increase the development time, lower the contrast, and lower the speed.

[paulbarden]

For making negatives, the developer is the variable.

Correct: make sure you use a developer intended for making negatives, or your choice of collodions is going to be irrelevant.

[Mark Kononczuk]

So what developer do you recommend for Old Workhorse negative?
(For lanscapes and naturally lit portraits)
I tried ferrous sulphate with a cadmium bromide, cadmium iodide, ammonium iodide and ammonium iodide collodion in the past which was very good and i tried pyro with potassium iodide and potassium bromide which was ok.

[paulbarden]

So what developer do you recommend for Old Workhorse negative?
(For lanscapes and naturally lit portraits)

Any developer that states it is for making collodion negatives will be appropriate.

[Mark Sawyer]

So what developer do you recommend for Old Workhorse negative?

Try this:

Vinegar (5% Heinz): 1 liter
Ferrous Sulfate: 30 grams
Sugar: 30 grams
Everclear 190: 200ml.
Distilled Water: 400 ml.
Used Developer: 750ml.

The distilled water is optional, you may want to compare with and without. You can also substitute 90% rubbing alcohol for the Everclear.

You'll also find some collodions adhere better to glass than others, but none are great. Whether it's the salts or the raw collodion that makes the difference, I'm not sure. Ask around.

[Mark Kononczuk]

Thanks

[paulbarden]

see also: https://www.collodion.com/forum_posts.asp?TID=313&title=negative-developer

[Mark Kononczuk]

I can’t access that link
Is there any literature on the internet about collodion negatives? I’m struggling a bit to find information, most paper books seem to be unavailable in Europe.

[paulbarden]

I can’t access that link
Is there any literature on the internet about collodion negatives? I’m struggling a bit to find information, most paper books seem to be unavailable in Europe.

A search engine will locate the resources you seek.
One of the first resources I found when Googling "how to make a wet plate collodion negatives" was this: https://timlaytonfineart.com/wet-plate-collodion-negatives

This one is also quite thorough: https://unblinkingeye.com/Articles/WPC/WPC2/wpc2.html

That said, I suggest you try to buy a copy of Quinn Jacobson's Chemical Pictures: Making Ambrotypes, Tintypes, Negatives and Prints off Amazon, if they can ship you a copy.