Kodak Thiourea

[Tom Taylor]

The Cookbook formula for Kodak Gp-2 gold protective toner calls for "Kodak Thiourea." Is this that same as "regular" Thiourea or is it a special proprietary Thiourea? I searched online and could find no reference to it.

 

[koraks]

Is this that same as "regular" Thiourea

I'd assume so. The thiourea-gold toner I've always used works fine with plain old thiourea in any case. I don't know what would have to be 'Kodak' about it.

 

[pentaxuser]

I'd assume so. The thiourea-gold toner I've always used works fine with plain old thiourea in any case. I don't know what would have to be 'Kodak' about it.

Sounds like a well reasoned conclusion needing only one reply but we can't surely let it rest at one reply on Photrio can we?

pentaxuser

 

[MattKing]

It might be a packaging of Thiourea that is of a particular concentration/purity/density.
If so, the measurements in that recipe would be somewhat dependent on using it.

 

[Quiver2]

It might be a packaging of Thiourea that is of a particular concentration/purity/density.
If so, the measurements in that recipe would be somewhat dependent on using it.

Or it could have been Kodak branding every thing photo related that they could. It's a bit like a flashlight made by a battery company with instructions to only replace the batteries with their brand.

 

[MattKing]

Or it could have been Kodak branding every thing photo related that they could. It's a bit like a flashlight made by a battery company with instructions to only replace the batteries with their brand.

If it was a Kodak publication that the recipe originated from, that might make sense, but my understanding is that this came from the Darkroom Cookbook.

 

[MattKing]

Here is another report of a recipe, this time from this link via the Rochester Institute of Technology:
https://scholarworks.rit.edu/cgi/viewcontent.cgi?article=6317&context=theses

 

[Don_ih]

It might be a packaging of Thiourea that is of a particular concentration/purity/density.

If it says "thiorea" on the package, then it should be ~100% pure. No?

 

[snusmumriken]

As far as I understand, photographic chemicals supplied as solids differ from other grades in (a) having low levels of contaminants that might affect the photographic process; (b) particle size, for easy dissolving. Thiourea dissolves easily anyway.

I don’t see how density could differ between grades, if the chemical composition is the same. So 5g should be 5g whatever grade you use, unless contaminants are a really big deal. In 2 min of internet searching I found no mention of that being the case.

Wikipedia notes that there are 2 isomers, with the same formula and therefore density. It isn’t clear which would be used in photography, or whether it matters.

I reckon this is a case of Kodak slapping yellow stickers on everything they could, as @Quiver2 suggests above.

 

[lamerko]

I assume the same as Kodak Elon - pure thiourea. It should be readily available everywhere and at a nominal price - here it's 4$/kg, the hard part is convincing the merchant that you don't need a 25kg sack...

 

[MattKing]

I reckon this is a case of Kodak slapping yellow stickers on everything they could, as @Quiver2 suggests above.

If this is essentially a reprint of a very old recipe, it may be from back in the day where Kodak thiourea was available from the Kodak shelf in your neighbourhood corner drugstore. Kodak products like that were branded and labelled back then like dish soap is branded and labelled now, and in some parts of the world, just as accessible.
If that recipe was from 1980, you would have an argument!
And if it was from 2022, it would be just weird.
Reaching conclusions about how things once were marketed based on current context is an unreliable endeavour.

If it says "thiorea" on the package, then it should be ~100% pure. No?

Or some very high percentage - I don't know whether it comes in a range of grades.
But I do understand that it comes in a variety of physical forms, and it is used for a wide variety of non-photographic purposes such as silver polishing and in a bunch of industrial processes, so it is quite possible that the "Kodak" stuff differed in practical ways from the stuff available from other sources.

 

[Don_ih]

At any rate, I know of no instance where you need to specifically use Kodak branded chemical X in a formula instead of some other brand, just as there's no reason to use Ansco branded chemical Y or DuPont branded chemical Z. Kodak had the distinction of having a couple of pet names for chemicals - like Elon and Kodalk.

 

[mshchem]

Kodak packaged beautiful chemicals. Their suppliers provided really nice clean chemicals. I wouldn't worry about the Kodak brand. Just find a nice clean free flowing material.

 

[relistan]

All the old Kodak recipes specify Kodak versions of the chemicals. This was probably both to sell their own chemicals, but also, as Matt mentioned, to make sure people know they could get it at their photo shop. I expect that it also helped guarantee repeatable results. In the pre-Internet world you didn't have forums for recourse when things didn't work. If you didn't live in a city where there might be a club with experienced folks, or a university or school with a good photo dept. then you were out of luck troubleshooting.

The cookbook undoubtedly copied the Kodak recipe and did not remove "Kodak" from the thiouerea.

 

[Tom Taylor]

The formula first appeared in the 3d edition of the Cookbook and is credited to a Jonathan Bailey. To use it today I suppose you could substitute 25mL of a 1% gold chloride solution for the .5gm gold chloride ((50% Au) and use generic Thiourea for Kodak Thiourea. The same edition of the Cookbook gives a replenisher formula for GP-2 credited to the same Jonathan Bailey.

 

[MattKing]

To draw an analogy, when that formula was newly published and shared, it was probably similar to your Chrysler automobile's owner's manual specifying a MOPAR product number for the brake fluid.

 

[mshchem]

In theory different companies products could be substituted. I wikipedia ed Metol....

"Aktien-Gesellschaft für Anilinfabrikation (AGFA) sold this compound under the trade name Metol, which became by far the most common name, followed by Eastman Kodak's trade name Elon."

 

[Don_ih]

It's no different from recipes hosted on websites owned by food manufacturers.

Kraft no-bake raspberry cheesecake cupcakes:

It's not about availability. It's about selling stuff.

 

[snusmumriken]

In theory different companies products could be substituted. I wikipedia ed Metol....

"Aktien-Gesellschaft für Anilinfabrikation (AGFA) sold this compound under the trade name Metol, which became by far the most common name, followed by Eastman Kodak's trade name Elon."

Compared with Metol, Elon has a slightly musky whiff.

 

[AnselMortensen]

Compared with Metol, Elon has a slightly musky whiff.

 

[mshchem]