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Very weird stuff with homemade emulsion

Isaacm9

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Hi, posting here again about my attempts to make a homemade emulsion, based on mark osterman's recipe on the light farm. My first batch had some weird emulsion gelling issues, and it was very insensitive in comparison to the estimated 5 ISO listed. This second batch is slightly more sensitive, but is still probably around 0.5 ISO. It also has a weird issue with tons of spots and flecks dispersed evenly throughout. I'll attach the test image I just made, but does anyone know what this is?

I'm considering getting a new batch of gelatin to see if that might be an issue, but there's still the issue of sensitivity. Does anyone have any recommendations for a slightly easier emulsion that I could try to make? I'm considering Kevin Klein's, but I know that there are some super knowledgable people here who might have better options.

Edit: attached an inset image
 

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The first thing that comes to mind is extreme clumping of the silver halide particles, which might also explain the low sensitivity as most of the silver ends up locked in these agglomerates.
 

A sincere question: Is there a reason you're not considering using a Light Farm recipe, rather than one of the contributors to the site? Both the potassium bromide (KBr) and ammonium bromide (AmBr) are excellent and come with full instructions. http://thelightfarm.com/cgi-bin/htmltutgen.py?content=15Jun2013
Regardless your choice, good luck and great fun.
Denise Ross
 
koraks said:
The first thing that comes to mind is extreme clumping of the silver halide particles, which might also explain the low sensitivity as most of the silver ends up locked in these agglomerates.
Click to expand...

Interesting, that could make sense! Do you know what could cause this?
 

Hi Denise! Thanks for all you do to make this information available. I wish I could give you a better reason, but honestly I just chose one and went with it. I have looked at your recipes and they are very well documented. I think your KBr emulsion will be my next experiment, as I already have all the materials needed. Hoping to be able to share some successful images in the coming weeks!
 
Isaacm9 said:
Interesting, that could make sense! Do you know what could cause this?
Click to expand...

I'm sorry, I'm not experienced enough in DIY emulsion making to offer very concrete suggestions. The page @dwross2 linked to contains a few examples that sort of seem similar; in that case, it was apparently overdevelopment beyond what the emulsion could bear. Maybe it's similar here? Although that wouldn't explain the low speed as such.
 
It looks like it could be aggregation from too little gelatin in make or coating.

The emulsion gelling issues could have been caused by getting the gelatin too hot.
 
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