 |
 |
From: Patent Tactics, George Brock-Nannestad Hello, Mike, you were mostly correct, but we do not want even the smallest error to go down in history, do we? So, in order to obtain precision: > On 8/15/2010 10:32 AM, Randal Baier wrote: > > Well, Mike, speaking for all the jerks out here, I'd like to know the >> difference between the two. I certainly didn't catch that. Gee, I thought it >> was a cut, but I guess it was a slice. Mike: > > They are two entirely different machines based on two entirely different > principles. They are as different as an inkjet printer is from a dot > matrix printer is from a laser printer. The program showed and > described a mimeograph but the guy the showed at that point described a > ditto, spirit duplicator, or hectograph. ----- already here we need more precision. The Hectograph was a flat-bed printer. You wrote or drew with special ink on a rather non-absorbent sheet, pressed it against the surface of the jelly-like substance, and the ink transferred (now a mirror image) to the substance. You could then press up to 100 (hekto in Greek) increasingly weak copies onto empty sheets. I have recipies of how to make the jelly-like substance - it was in boys' magazines. > > The mimeograph ............................ ok until: Thousands > of copies can be made if you are careful not to wrinkle or tear the > stencil because you can re-ink the cotton backing from behind. ----- actually the re-inking is from the back all the time, through the stencil. If you > accidentally get ink on the front of the stencil by putting it on > backwards you have ruined it. The ink comes thru the back. ----- I can add that Gestetner in the UK were great competitors, and that Rex- Rotary from Denmark (manufacturer Zeuthen & Aagaard) was also quite known in the 1950s and 60s. In the 1970s they invented a practical scanner, in which electrical sparks created holes in a continuous, non-woven stencil, dependent on the reflection from the scanning part. There were two drums on the same shaft; the scanning drum and the eroding drum. It was very much like old telephoto, but I think they still got a patent. > > The 'ditto' machine used a plain paper where a carbon ink paper is behind > the paper. ----- the whole point is that it is not carbon ink - it is not pigmented at all. It is a soluble color, originally aniline-based (the basic purple colour) You write or type on the front of the paper without cutting > thru it -- use the typewriter ribbon in normal position -- the carbon > ink gets deposited on the rear of the paper. This stencil is then > placed on a plain solid metal drum with the inked surface outwards. (If > you put it on backwards--no harm. Just remove and put it on > correctly.) There is a container where a clear spirit solvent is > poured. This spirit fluid slightly dampens the printing paper which > picks up the ink as it passes thru the machine. Because the PAPER is > dampened with the spirit solvent, it has that sweet smell for a few > hours. Only a hundred or so copies can be made before the carbon [NO!; as per above!] ink on > the stencil gets used up. While most of the carbon ink sheets are > purple, there were about five or ten different colors available, and you > can switch these carbon sheets and make a multi-colored stencil. (You > have to use different machines with different stencils if you want to > have multi-colored mimeograph copies. A separate stencil for each > color, and usually a different machine because it takes a half hour to > completely clean a machine!) > ----- double-sided printing was not possible with the spirit duplicator, but certainly with the proper stencil one. Kind regards, George