Ammonium thiosulphate crystals

[mtuell]

From my darkroom, I took a drop of dilute Ilford Rapid Fixer, which besides water is mostly ammonium thiosulphate, so I'm assuming that is what these crystals are. I placed that drop between a slide and cover slip, and I think it is still growing almost two weeks later. I'm going to repeat this with stock (undiluted) chemical, and a few other ideas, too.

This first one is a PMax stack of 10 with a 2x Plan Apo with crossed polarizers.



And an interesting region that was a "beach-head" against the intruding air, sticking out into the "ocean". This is a single exposure with crossed polarizers 4x.



Now, I switch to 40x Hoffman, and with a little input polarizer tweaking, I can get both HMC and polarization effects... kind of cool, I thought.



There is a hexagonal hole in my crystal!

Here is an animation showing the effect of rotating the polarizer:

https://lavinia.as.arizona.edu/~mtuell/ ... io-rot.gif

And a couple more regions with the same setup. Of course, rotating the specimen is another degree of freedom that I only briefly looked at.





As usual, there are larger and stereo versions on my site in the stereo images section.

Mike

[carlos.uruguay]

I like the third

[mtuell]

My previous images were with diluted rapid fixer, as it is used for photography. I decided to try undiluted solution, too. It takes quite a while for crystals to develop nicely when not exposed to air - this has been sitting around for something like two weeks, and I think there is still liquid between the slide and cover slip - the crystals are still growing.

Again, this is with a combination of Hoffman and a little polarization thrown in for color. You can get the 3D effect and retardance colors at the same time, to some level. Full disclosure here: I did tweak up the saturation for this particular photo. It is a single exposure.



Here is the same region removing the HMC mask, and crossing the polarizers - again a single exposure.



While I have seen more diverse crystals, this does create a fair number of forms. Oddly, a few days ago, it made a very nice line of crystals, but the next day, it was gone! The only thing that makes sense is that humidity from the evaporative cooler added enough moisture to re-absorb those crystals back into solution. Anybody experience this type of thing before?

Mike