Take note of the detail from the black background chemigram, where you see a little bit of pinkish purple where the butter was. This is not a pinkish purple that was created chemically, but rather an unstable lumen area whose color is the result of light exposure. It happened because butter was not removed from that area of the print before the 3 minute fixing bath. It was later removed by washing the print in dish washing soap before the final 5 minute running water bath. Being that it is unfixed, it will continue to change over time, getting darker and maybe shifting hue. If I fix it now, after having been exposed to a lot of light, it will likely “bleach back” to an off-white or yellow.

Concerning the color background print, the lighter mark on the lower portion of the print is where I was touching the print with my gloved hands, apparently with enough fixer on my glove to lighten that area.