How does an image in instant packfilm transfer from the negative to the paper?
Helping to save analog photography one exposure at a time
By diffusion through the developing paste.
There is a good description in the biography of Edwin Land, 'Insisting on the Impossible'.
"People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.
This page has some nice diagrams of how the image is transfered to the print.
its crapped out.