Polaroid SX-70 was exposed from the front and required a white goo to act as backing for the image which formed. Kodak exposed from the rear and used a black goo to cover and protect the emulsion after exposure. The final image diffused to the white permanent undercoat to form the image.

This is a very simplified schematic of the packages.


EXPOSE >> Support / mordant / GOO with TiO2 and indicator dyes / Tripack emulsion layers / black backiing / support


EXPOSE >> Support / GOOD with carbon black / Tripack emulsion layers / TiO2 with mordant / support

In the Kodak scheme, the final image layer was a solid material and the exposure was directly onto the emulsion thereby making the image more rigid and sharp. The Polaroid layer, being on the goo required some time to achieve permanent rigidity and therefore the image could be destroyed or distorted by rough handling. You could touch it and watch it distort much as you can touch a flat screen display and see your "fingerprint". Trouble was, those touches could be permanent on an SX-70 print.

The Kodak method used direct positive emulsions and released dyes in proportion to a positive silver image or in the PRESENCE of a silver image. The dyes were Azo dyes. The Polaroid method used normal negative working emulsions and the dyes were HQ based Azo dyes which moved in the ABSENCE of silver development.

Anyhow, the difference between these two led the Kodak attorneys to advise Kodak management that their method did not violate the Polaroid patents. Huge differences and the need for invention will differentiate between the two methods was their argument. The judge (who owned a LOT of Polaroid stock and didn't know chemistry) did not agree and claimed that the two methods were roughly identical, but he ruled that Kodak had not infringed out of malice and therefore did not impose the maximum penalty.

The judge offered to recuse himself from the case when the stock situation came to light, but Kodak thought it had such a good case they decided to continue with the same judge.

BTW! Polaroid did not use the settlement $$ wisely and we know what happened to them. Kodak lost so much that it became an issue with their entry into digital. They lost millions on this and therefore were reluctant to take on something new with a very low cash reserve.

There you have more than you ever wanted to hear on this!