Question for the chemists.

Lachlan Young said:

An awful lot of the stuff people seem to dredge up from Crawley is decontextualised stuff from a long time ago, when the emulsions he was talking about were on the cusp of obsolescence, if not already fully there. His writing should often be taken with more NaCl than a litre of Microdol.




If it reassures you somewhat, you successfully repeated what the big research labs found in the 70s/ 80s.

Something else worth looking at is the use of PMT restrainer and a carbonate buffer, as it seems to offer the potential for fine granularity (via development inhibition) yet with optimal sharpness - and not requiring the use of larger levels of sulphite to act as a grain solvent. It seems to be the basis of Ilfosol 3.

Click to expand...

Thanks, very interesting. I’m on a bit of a photochemistry hiatus, occupied with house projects, but will add that to the list of things to look at when I’m back (hopefully by late autumn).

Ok, my test film came in, and I got some dry days to shoot. One gram per liter of ammonium chloride appears to give more speed. Five stops below middle grey with the chloride seems to match four stops without on the negative; this is visually comparing the two strips side by side. There seems to be no appreciable increase in fog.

Interestingly, I saw someone add salt to Rodinal in an attempt to reduce grain, the grain looked the same, but the shadows looked brighter. As far as obsolete goes, I have some K grain emulsions to try.

My next goal is to see how much chloride I can get in TEA.

boring old man said:

Thank you for the replies, I have done many searches, It was conversations between PE, Ian Grant, and Gerald Coch, that peaked my curiosity. I was just trying to get a few grams of sulfite into a PCTEA type developer, to boost shadow speed a little. My first idea didn't work, I have a few other options, but was wondering if a different solvent might achieve similar results. I know i could just add it to the working solutio, n, but I like futsing to keep busy sometimes, I could probably just get T-max to do the same result, but what's the fun in that.

Click to expand...

There's an old thread about adding sulfite to PC-TEA:


I thought I remembered reading here in Photrio that PC-TEA with sulfite did not work as well as just using XTol / MyTol, but it looks like that comment was about metabisulfite. Here's a quote from @Jordan (who last posted in 2015):

To adulterate a PC-TEA stock solution in a similar way, I would add 75 ml of the stock solution and about 31 g of sodium metabisulfite per litre of water -- this also gave good results but is not as close a match to XTOL because of the alkalinity of TEA.

Click to expand...

Anyway... If you want to add sulfite to PC-TEA, maybe look into MyTol?

dcy said:

There's an old thread about adding sulfite to PC-TEA:

PC-TEA with Sodium Sulfite

PC-TEA for film creates razor sharp grains with no solvent effect that can create mackie lines or smooth tonality. It is good but for enlarging or pushing it is a bit harsh at times. I have had great success pushing TRI-X in Xtol to 1600 and enlarging a 6x6 neg to a 16x20 print. I tried adding...

www.photrio.com

I thought I remembered reading here in Photrio that PC-TEA with sulfite did not work as well as just using XTol / MyTol, but it looks like that comment was about metabisulfite. Here's a quote from @Jordan (who last posted in 2015):



Anyway... If you want to add sulfite to PC-TEA, maybe look into MyTol?

Click to expand...

Yes, Thank you for the link. it's hard to explain, I'm just trying to make a concentrate, not exactly like PCTEA, but similar. I'm trying to add a small amount of solvent, for a possible speed enhancement. This is more about the doing, than the having; I just like to try unconventional approaches. I can't do anything the easy way.

What kind of astronomy do you do?

boring old man said:

Yes, Thank you for the link. it's hard to explain, I'm just trying to make a concentrate, not exactly like PCTEA, but similar. I'm trying to add a small amount of solvent, for a possible speed enhancement. This is more about the doing, than the having; I just like to try unconventional approaches. I can't do anything the easy way.

Click to expand...

Oh, I understand 100%. Experimenting with chemistry is a big part of what I like about this hobby.

boring old man said:

What kind of astronomy do you do?

Click to expand...

Hope the moderators don't mind this tangent:

I make computer models to understand how planets form. I'm an astrophysicist; meaning that my focus is understanding the physics rather than doing the observations. I make hydrodynamic simulations the protoplanetary disk around the star where planets form. Most of my work is about understanding how planetesimals form ---- those are ~ 100 km rocks, like asteroids, that are the building blocks of planets. Asteroids are planetesimals that never made their way into a planet.

My interest is not about asteroids for their own sake. I want to understand how the Earth came to be. Planetesimals are just the least understood step in the process. But I also do work on the other steps, from dust to planet.

dcy said:

Most of my work is about understanding how planetesimals form ---- those are ~ 100 km rocks, like asteroids, that are the building blocks of planets.

Click to expand...

Soooo.... planetesimals are to planets what grains are to the developed photo.

Now I understand the link .

dcy said:

Oh, I understand 100%. Experimenting with chemistry is a big part of what I like about this hobby.



Hope the moderators don't mind this tangent:

I make computer models to understand how planets form. I'm an astrophysicist; meaning that my focus is understanding the physics rather than doing the observations. I make hydrodynamic simulations the protoplanetary disk around the star where planets form. Most of my work is about understanding how planetesimals form ---- those are ~ 100 km rocks, like asteroids, that are the building blocks of planets. Asteroids are planetesimals that never made their way into a planet.

My interest is not about asteroids for their own sake. I want to understand how the Earth came to be. Planetesimals are just the least understood step in the process. But I also do work on the other steps, from dust to planet.

Click to expand...

Yeah, I'm trying to make a developer for 4X5, so grain isn't my primary concern, especially as I plan to use them for contact prints. I was trying to get a mild speed increase, because I'm starting with cheaper film IE Foma based. I really don't want to BOZO T-max, Delta. A concentrate is better right now, because storing X-toll is a hassle in the new (old) house. I need to finish off the half finished attic so I can print again. I never got a scanner; ironicly I went to university to learn coding, and digital seems less "real" to me. I'm still in the early stage of design, I have stuff that works, but I'm still juggling ratios, so I don't plan on starting a thread yet. My developer probably wouldn't suit you, the grain would most likely be overwhelming in half frame.

Hydrodynamic, do you model like a fluid?

You like the chemistry, wait till you try to make your own emulsion, there's a rabbit hole for you.

boring old man said:

Yeah, I'm trying to make a developer for 4X5, so grain isn't my primary concern, especially as I plan to use them for contact prints.

Click to expand...

This might be a dumb question but... why not use straight PC-TEA?

boring old man said:

Hydrodynamic, do you model like a fluid?

Click to expand...

Exactly. The gas is a fluid and for solids, sometimes I model them as individual particles that feel aerodynamic drag, and sometimes it's better to model small dust as a pressure-less fluid.

boring old man said:

You like the chemistry, wait till you try to make your own emulsion, there's a rabbit hole for you.

Click to expand...

It didn't start like PC-TEA, it's evolved closer to it though, like how everything becomes a crab. I'm trying different P C ratios, different TEA concentrations, I have a third developer included, I'm testing the addition of solvents for speed boost, ect. A large part is to try and understand what the knobs do when you turn them; plus, I like having things that are "mine" for some reason.

I once tried to calculate aerodynamic lift in a nebula, at speeds close to C, for fun. Trying to equate space densities with atmospheric densities was fun, and my answer was most likely wrong, but it did kill a couple of evenings.