chemical free photographs

what is a chemical free photograph ?

usually when i make a photograph i expose paper to a small amount of light.  i either project a negative from an enlarger onto the paper
or i put the negative on top of the paper itself and expose it to a small amount of light, or i put materials on the paper and use a small amount of light
to expose the paper.  the paper is then put through a developer, where the image appears onto the paper and then a fixer to remove all the unexposed
silver so it will be “light safe” .

last fall i wondered what would happen if i just made a long long exposure with paper, in a camera or in contact with a negative.  would an image appear on the paper?  would it be able to be saved somehow so it could be viewed ?  or would it just fade away?  there were people I met who place who
put plants and “living” materials onto paper and expose it this way.  the plants ‘sweat” and “cook” on the paper and a photograph is made showing the outline
and translucency of the plants.  the stuff that oozed out of the plants reacts with the photo paper and the image can be fixed in fixer and toned and can last as long
as any photograph.  i was hoping to do something similar, but without plants, and without making a photogram.

i loaded an old sears box camera up with paper and left the shutter open for an hour or so, and an image was on the paper.
i put a 4×5 negative on a sheet of paper and put that in a contact frame and left that outside in the sun, and in an hour an image appeared.
soon after i began to make my own cameras out of foam core and i bought simple lens cells.  the largest camera i made was 12×16
and i made 11×14 prints with it.  i taped paper inside after the camera was focused and left it for upto 4 hours.

i did run into trouble though.  i tried to fix the images and make them light safe, but they faded to white.  my exposures were too short so the fixer bleached the image off of the paper.  instead of using rapid fixer, i bought hypo ( sodium thiosulphate ) and with the help of a friend learned of a milder way to fix the images,  a way used for printing out paper.  unfortunately my images were still too underexposed and they bleached.
i did manage to scan many of the images i made so they were saved somehow.    the next ones i made will be exposed for two or three times my initial exposures
and hopefully will last longer.