Kodak Photoresist

[Mustafa Umut Sarac]

I was foolishly swirling in internet to find the method of rotogravure printing of 1990s and late 1980s excellent National Geographic Prints. Its very hard to learn how these copper drums been engraved exactly 30 years ago and it is harder to learn which inks been used.

There are 4 ways , carbon paper, photoresist, mechanical engraving and laser

In india , they are still using carbon paper and I am not no more interested what digital hdr been used at ngs.

Now , kodak photoresist is a natural chemical which smells like an honey and at the early days , its been used to make photoresists of semiconductors. And the rotogravure drums.

It can be applied on giant glass or steel plate with rotation and bake few hours at 80 celcius and use the sensitizer - they say developer - and uv expose.

Patent is very old and I found few produces that formula and advanced ones.

After expose , wash it and your gravure is ready. Acid do the remaing job.

I think 10 miliwatt is enough to expose http://transene.com/pkp/

There are immense amount of things that photoresist can do , you can get your pre etch engraving ready at the mountain top , you can may be use as emulsion , you can print your art making filter with transparent grids on glass etc etc.

By the way , that photoresist hardens with long grades depending on uv source.

When you wash the remaings , its possible to etch more than hundred different depth ink reservoir in to copper drum.

 

[MattKing]

I was foolishly swirling in internet

Umut:
It occurs to me that this would make a very good APUG signature line....

 

[dmr]

Thanks. I do find such things interesting.

We subscribed to NG when I was growing up. It amazes me that those color photos could be mass-reproduced at such high quality and precision.

One job I had many years ago was with a mom-n-pop non-union print shop and the most we ever did along those lines were simple halftones. I remember the care you had to take to get those looking good! (LOL, most of my "wet" experience is doing Kodalith.) To do four-color gravure seems to be incredibly difficult, particularly that many copies and that many photos at such consistency.

 

[Mustafa Umut Sarac]

Hello dmr,

NG made me a sailor , archaeologist , pre press man and printing press company manager plus ship cargo operator and gmdss operator.
I spent very long time to decipher 1980s 1990s prints. As far as I find is the beer effect where mr beer from england and an professor.
He wrote the rules of ink thickness and color change rules. I think these prints depends on that effect. I will write an article abouıt it.
I will let you know

best,
umut