3 ms·
That's very cool, I'd not heard of offset printing before. It's a shame your family had to sell their business, as from what you mention it sounds like not all
by anfractuosity 9y ago
That's very cool, I'd not heard of offset printing before.
It's a shame your family had to sell their business, as from what you mention it sounds like not all of the printing method changed.
I was wondering with the kitchen method, how you'd get a photo onto the foil, but as you mention a laser could be used. One thing I was slightly confused about, is, is it always necessary to use a coating on the aluminium for that approach.
I guess you could also coat the foil with the photosensitive emulsion you use for PCBs too, and then etch that.
- bane 9y agoYeah, I guess I omitted that step as I'm not entirely sure how the actual lithography was performed. I remember a large "camera" where the negative would go into the top and the sheet would lie underneath. It looked vaguely like the reverse of an old acetate overhead projector. How the image was etched in that process I simply don't remember, but I do remember the sheet going through a number of chemical baths and washings (and being reminded to stay clear of the chemicals as a child). So there may have been some phase where the sheet was treated with a photosensitive chemical before going into the camera, I simply don't remember the detail. This link [1] seems to have some details. It looks like the plates run for a little over $1/plate for the smaller ones. [2] 1 - http://www.offsetprintingtechnology.com/sub-categories/offset-printing-plates/ http://www.offsetprintingtechnology.com/sub-categories/offse... 2 - https://www.valleylitho.com/acatalog/Valley_Litho_Supply_Plates__6.html https://www.valleylitho.com/acatalog/Valley_Litho_Supply_Pla...
- HeyLaughingBoy 9y agoGuessing it was something like an Agfa photostat camera. We had one of those at my first job. We used it both for making camera-ready art for ads (we were a tiny business) or positive film to send off to the PCB house to get boards made. IIRC, the film was standard Kodak 8.5x11 size negatives and the processing was pretty simple. I would do everything from initial tape & wax puppets to the final artwork. Not what I expected to be doing in my first engineering job, but it was fun. I took a printmaking class sometime later. I think the litho "stone" is made photosensitive and etched, but that aspect of the process is fuzzy. Most of the class was about positive prints and I spent most of my time doing intaglio and lino block printing.
- bane 9y agoYeah, that looks basically like the device!