Rear Exposed Instant film technology...

[Ektagraphic]

Hello there-
I'm sort of hoping PE will find his way to this thread because I know that Kodak's instant technology was rear exposed also...anyways...How does the image get exposed onto the film with rear exposure instant film technology such as the Fuji Instax?


Patrick

[Photo Engineer]

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.

POLAROID:

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

KODAK:

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!

PE

[filmamigo]

Fascinating! Is there any connection between Kodak's and Fuji's version? I.E. selling or licensing? Or did Fuji arrive at a similar design on their own?

[Photo Engineer]

I have no idea!

Sorry.

PE

[Ektagraphic]

Thanks PE...That's quite interesting! I am fascinated by these technologies!

[Ralph Javins]

Good morning;

Fascinating is only one element of this issue.

Then there is the mind numbing frustration that occurs when you mix in the curious legal parts along with the personalities involved. I still have a working Kodak Color Burst camera, but nothing to feed it. Of course, now I can no longer buy any film from Polaroid to go into my pack film holders for the view cameras also.

This kind of a thing seems to happen much too often. The history of the Cord automobile and the rotating legal challenges made by "The Big Three" automobile makers back around 1950 who simply depleted the financial reserves of the little company before it could really get the Cord into full production. Then we can also look at what happens every day in the "legal system" division associated with "family law" or "domestic relations."

[pdexposures]

Fuji licensed Polaroid's pack films in the 80s in trade for some of their work with magnetic tape. Since pack films are exposed through the rear, and offer a similar development style to the rear exposed Kodak integral instant films. It is reasonable to assume that when they chose to make an integral version, they would pull the technology from what they already knew how to do. And simply put it into an integral form.