Saturday, January 30, 2010

Land's key patent filed in 1944, issued in 1950 US2500421

The USPTO was slow in issuing this patent by Land, which is understandable since it was abandoned and refiled, possibly with additional material as was the practice of the time.

We are studying this one today, mostly for the description of the preparation of the receiver sheet.

Here is the link to a pdf of US2500421

After reading this, one has to wonder if the titanium dioxide was thought of as a "nucleating agent" or even a particle.


gerald said...

doesn't only the integrals contain titanium dioxide? however, if you haven't come across the material safety data sheets from polaroid, they might contain some useful information for you as well (they vanished from polaroids website, but can still be found here):

Bob Crowley said...


Excellent - thank you. The later laser patent discusses making a gradation of nanoparticles, which might occur naturally following Land's description. Rott's patent indicates that virtually any material will do - suggesting there are factors on the negs that are affected, and probably tunable, by the absorption, nucleation and ph of the receiver.

Anonymous said...

You'll note that the sixth page columns 9 and 10 are incorrectly imaged and have half the text missing - I have asked for this to be rescanned at the US Patents Office but the online copy still has this half page missing. Anyone got a paper copy that could supplement this missing info?