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So that’s where it gets it’s name. Somehow wood and IR response didn’t make sense to me.
So that’s where it gets it’s name. Somehow wood and IR response didn’t make sense to me.Mirko:
Good luck with your new film.
A point of nomenclature. It isn't a "wood" effect, it is a "Wood" effect.
It has nothing to do with the product we get from trees. It is the effect that is named after the infrared photography pioneer Robert W. Wood.
I guess to most people it makes indeed sense as the Wood effect is typically explained at an assembly of trees. And in this context wood is not the material but the assembly of trees as in a forest or wood.So that’s where it gets it’s name. Somehow wood and IR response didn’t make sense to me.
Nice video! Thanks for sharing details of the line. The slide die is not Troller Schweizer is it (was suspecting it would be)? Liberty or Premier Dies (EDI, now Nordson)? Maybe a European shop.
Quite possibly made in-house - many of these companies had serious engineering facilities. The Ciba/ Ilfochrome materials (apparently extremely tricky to coat - see elsewhere on Photrio) were apparently initially coated with a slot die setup before eventually moving to a slide coater.
Interesting. That would imply multipass. Dual layer slot die is quite possible, and I have seen design proposals for 3-layer, but beyond that is unlikely.
I have heard some of the trickiest coating was for the Polaroid products.
The last form of Ilfochrome is described here - https://www.photrio.com/forum/threads/emulsion-_-base-chemicals-_-cibachrome.64240/#post-912129 - the slide coated version - not sure how many layers the slot die version had. I understand that the machine in the video can do up to 3 or 6 layers in one pass.
Couple of patents for your perusal: https://patents.google.com/patent/US4041897A/en has some remarkable similarities to the machine in the video - perhaps unsurprising, given that it's a Ciba-Geigy patent.
https://patents.google.com/patent/US3973062A/en may have some relevance to what went before.
Thanks, interesting stuff. The first patent is standard art today, and appears to be the nature of what is shown in the video. The second shows some clever arrangements perhaps to get more layers without stacking too many layers on one slide die or to save real estate. I suspect controlling these merging streams could be challenging. I suspect 10+ layers on a single curtain die with a slide is mechanically quite possible today without these arrangements, but the arrangements may allow the combination of more incompatible layers (what you need to avoid is the mixing of layers, and if you have multiple layers it gets harder and harder to make the layers float on top of each other without mixing, or just as bad is mixing after impingement on the substrate). A key component missing are edge guides, but they may discuss this in the patents (I have only looked at the illustrations). Edge guides are not needed if the curtain is very short (i.e., slide coating as opposed to curtain coating- the video appears to show slide coating). The patents appear to be showing curtain coating.
If it's anything like Agfa's approaches, it may well be curtain coating, but the curtain may only be falling 15-50mm or so - which may not be terribly obvious in the footage. There are Agfa patents which cover the use of specific layer packages that enables potentially up to 6-7m/s line speed & the above mentioned curtain height - which the patent describes as 'completely unforeseeable to a man skilled in the art' - and given Agfa's & Ilford's fairly close relationship, it would not be surprising if the technology filtered through fairly fast in the late 1970's. The Agfa patents do mention curtain guides but are more concerned with layer package design & the use of a 'v-caster' caster design which they claim is optimal for delivering large numbers of layers at very high speeds & short curtain heights with minimal waste. Simon Galley (when he posted this, a director of Harman/ Ilford) described the Agfa Leverkusen coating machine as a 'triumph'.
Guess why Kodak collaborates with Agfa-Gevaert on microfilmsSimon Galley described the Agfa Leverkusen coating machine as a 'triumph'.
...However at the stage of insolvency of AgfaPhoto their management was more proud on their RA-4 coater which they considered the most modern in the world and could not understand that no one in the world wanted to have it. It finally went for scrap metal...
I wonder if Polytype built the machine.
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