View Full Version : Homemade Tri-x

Mustafa Umut Sarac
09-28-2007, 04:21 PM
We learned how to make polaroid and kodachrome emulsions . Now it is time for tri x. Photo Engineer , What are the patent numbers of tri x ? How can we do it ?

Best ,

Mustafa Umut Sarac

Photo Engineer
09-28-2007, 04:31 PM
I really don't know the patent #s for it.

It is basically (or was) and SRAD bromo iodide as I posted earlier, but with far more sophisticated chemistry. It also used blends of probably 3 emulsions to gain the proper tone scale.

Tri-x today is a double run with even more sophistication.

Thats about all I know for sure.

I have, in my head, the formulas for several emulsions including the graded core shell that I referred to earlier. I have seen it used for the fast component of films up to about 3200 ISO. The actual film speed is lower due to absorption dyes and the fact that it is being used as the fastest part of the film. The mid scale could be as low as 1600 or 800.

In any event, the double run would be silver and iodide run into iodide and gelatin. With time, the silver flow rate is increased as is salt flow rate, as the iodide proportion decreases to the desired % level. The final total iodide would be about 8 - 10% with a core of 100% iodide.

How is that for starters?

BTW, I missed something. How did we learn to make Polaroid and Kodachrome emusions? It must be about 1AM in Turkey. What are you reading? :D


09-28-2007, 07:31 PM
Thanks PE,

More questions. Apologies if I am hijacking this thread.

How would Plus-X differ? Does it use older technology?

Would it be possible to make Plus-X in a home lab?


Photo Engineer
09-28-2007, 07:45 PM
The original formulas for PX, Super XX and TriX were basically variations on an SRAD IIRC. They differed mainly in the method of pptn, temperature, ripening and etc to make the different speeds. They were all made from blended emulsions.

Some of them used toxic salts and this caused reformulation or elimination in the 60s.

Panatomix-x was different, but I know very little about it. Well, I know little of these others too, but a bit more than Panatomix X.


09-28-2007, 08:28 PM
Thanks PE,

Why is it necessary to blend emulsions in order to achieve a good tone scale?

Was blending a process that started in the 50's?


Mustafa Umut Sarac
09-28-2007, 08:40 PM
PE , It is 3.30 AM and I am reading about schack hartmann wave front sensors for to copy a Konvas - Lomo lens with a phase structure for zenit.
Second thing making doe tele lens for zenit
Third is to make digital back for zenit with a matt screen and a pinhole webcam.
I am forcing for to go back for the good days of lomo cinema equipment and tarkovski movies.
Listening Bach 699 and hey :)

Photo Engineer
09-28-2007, 09:14 PM
Mustafa, you are one busy guy.

Emulsion, no single emulsion can give the long tone scale desired for a negative film (or a positive film for that matter) and have the desired grain structure. All films that Kodak makes are made from blends of generally 3 emulsions; a slow, medium and fast. Color films have 9 emulsions, 3 for each layer. This is a generalization of course.

In a positive film, due to the higher contrast desired, the emulsions are closer in speed than in negative films. Of course this is changed if you process a negative film to a positive or vice versa, and differs if you have a monodisperse vs a polydisperse emulsion. Polydisperse emulsions inherently have longer tone scales whereas monodisperse emulsions have shorter tone scales. Other differences lead to major differences in the design of the film itself and the shape of the curve.

A person could give a 1 week course, 8 hours / day on system design. It is a complex subject. And that would just be an introduction. It would normally be a full college course.

Hope this helps a bit.


Mustafa Umut Sarac
09-29-2007, 08:02 AM
Thank you PE , This is very interesting. ok , if one emulsion is not able to cover full grade of tone , may be one developer is not able to cover all grades.
May be we need to mix developers or we have to use multiple start stop developers per negative.
This is very interesting with my deleted idea , printing developer on to the paper.

Photo Engineer
09-29-2007, 10:02 AM

Developers, by nature of the fact that they develop all 3 of the blended emulsions, display the full tonal range of the negative. It is their nature to do so. To reveal a high contrast, short tonal range requires a special developer such as Kodalith developer, D-19, D-8, D-11 etc...

Also, in another thread here, I posted some high speed emulsion formula patents which show the entire spectrum of core shell emulsions.