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Coming off the heels of: Photogravure: What is it?.

I saw the first question and found it interesting and looked at the wikipedia article and noticed it said that it predated Daguerreotypes. I also remember reading about Daguerreotypes and thought they seemed similar to circuit etching.

So, what is the difference in the process, chemicals, and materials used in these processes?

They all are on a metal backing, and are light sensitive, but is that all they have in common? Can one cross process the other and obtain acceptable results?

Most interestingly, if they are similar enough can I "etch" a picture into pcb?

  • Things I probably should remember from my photography education; but do not :) – dpollitt May 6 '15 at 1:52
  • @dpollitt I'm actually really interested in the circuit etching as a photograph. I think that'd be really cool to make a "picture board" and run some LEDs through it. – SailorCire May 6 '15 at 2:25
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    There's a good chapter on each of these (although probably not PCB etching) in The Keepers of Light. I also have the new third edition of The Book of Alternative Photographic Processes arriving today so I should be able to bolster my own knowledge and answer this tonight. As for etching, I'd be surprised if you could get more than two tones there, you might need to dither - I can test this at the weekend perhaps. If the process is similar to standard PCB etching it should be fine. – Martin Foot May 6 '15 at 9:07
  • @MartinFoot any luck? – SailorCire May 14 '15 at 4:42
  • Actually I thought this answer was quite good so didn't spend the time learning yet (I was investigating anthotypes instead). I was about to delete the previous comment. – Martin Foot May 14 '15 at 8:02
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The following is probably not entirely accurate, but I will try to highlight what I think the main differences are. Also, keep in mind that most of the names used above are umbrella terms for whole families of processes that might differ significantly within one family.

I think photogravure and circuit etching can be seen as somewhat similar with respect to the etching part: In both cases the metal is directly etched (i.e., one could say that the metal plate "holds the picture"), using for example ferric chloride. In some parts, the etching is moderated by some substance, for example by hardened gelatine in the case of photogravure. In circuit boards, this will leave the conductive tracks, in photogravures, these parts will hold less ink, thus appear as highlights in the print. Of course, for photogravure there is the preliminary step of contact-printing a picture onto the gelatin and the final step of making a print from the metal plate. From a "usability" point of view, photogravure requires already some sort of (positive) film created by another process and the aim is to obtain prints made with ink. For the wider family of processes, see also photoengraving and photolithography. The process predating daguerreotypes is heliography.

For tintypes, the metal plate only acts as a support/carrier for the photographic emulsion, which is collodion containing suspended silver halide. If glass is used instead of metal, you get an ambrotype. These plates are exposed directly in camera, then developed using a ferrous sulfate developer, and fixed using sodium thiosulfate (aka hypo) or potassium cyanide (warning: this last option is very dangerous!). They make a picture that appears as a positive (although, technically it is an underexposed negative). Both ambrotype and tintype belong to the family of collodion processes. This family also contains processes that are used to create actual negatives (i.e., ones used for making photographic prints) rather than positive-looking negatives.

For daguerreotypes, the metal plate is coated with a thin layer of silver, which is subsequently sensitized using halogen (or other) fumes. So one might say the metal plate also only acts as support/carrier, but the light sensitive material is more "closely" combined with the support, e.g. by electroplating. This plate is also directly exposed in camera and then developed using mercury fumes (please don't do this at home unless you really, really, really know what you're doing!) and fixed with sodium thiosulfate. The image appears positive or negative, depending on lighting and background.

So, tintypes and daguerreotypes are somewhat similar from the "usability" and "general process outline" point of view: In both cases, the metal plate is coated with a substance (collodion for tintypes and silver for daguerreotypes) that is then sensitized, exposed in camera, developed, and fixed. However, the (chemical) details are quite different, and to the best of my knowledge there is nothing like "cross-processing". However, there are many variants within the family of collodion processes, so a fair amount of experimentation is possible here.

Photogravure on the other hand, as outlined, is quite a different process with a different purpose: Here, you already need a (positive) image and the aim is to create a plate that can be used for intaglio printing.

Note that the collodion process is not too complicated to recreate at home and is reasonably safe when following the usual guidelines regarding safe handling of chemicals (and staying away from the potassium cyanide). This is not the case for daguerreotypes, they are quite complicated and very dangerous to create. If you intend to make daguerreotypes, it's best to do it under the guidance of an expert first, i.e., find a workshop or similar.

As others have pointed out, the Book of Alternative Photographics Processes by Christopher James is an excellent source for further information.

Finally, you can etch photographs into PCB boards, see for example here or here. Nothing stops you from using a plain photograph instead of a "meaningful" circuit. However, such a circuit board would most likely not be good for any electronics. If you want such a thing, you would need to do some conversion of the photograph first, e.g., akin to TSP Art, see also here (but of course with the aim of generating a meaningful circuit).

  • Best username ever. – dpollitt May 6 '15 at 15:27
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    @dpollitt Thanks, I have used it in many places for a long time and it has been useful in so far as it always was available as a username for some reason. – godfatherofpolka May 7 '15 at 8:04

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