> On Oct 13, 2015, at 11:19 AM, Jay Jaeger <cu...@charter.net> wrote:
>
> On 10/13/2015 12:02 AM, tony duell wrote:
>>
>> ...
>> It appears to be electrolytic. You have to keep the paper damp (there is a
>> wick
>> inside that you put water on. The paper goes between a helical electrode on
>> a spinning drum and a straight strip, the latter being replaced when you fit
>> a new
>> roll of paper. Whether it is some chemical in the paper that changes colour,
>> or metal
>> depositied from the electrode I don't know (the former seems more likely).
>>
>> I have never got it to work. Whether that is due to electronic problems
>> (that I can
>> fix) or chemical problems with the old paper (which I can't) I don't yet
>> know.
>>
>> -tony
>>
>
> I had a little Comprint printer in the 1970s/1980s that used something
> sort of like this. The paper was aluminum coated, thus conductive. The
> head was a high voltage electrode unit that burned away the aluminum
> layer. (I can't imagine any kind of deposition technology in that
> era...). The head flew back and forth really fast, doing one pixel-line
> at a time.
There are all sorts of oddball printing technologies from back then. I
remember one (from a lab instrument, not a printer or terminal) that used
aluminum-coated paper, but the coating was on the back of the paper. The
writing was done with a high voltage electrode just as you describe, but the
result was that the sparks would scorch the paper and leave a thin black mark.
I don't remember what the VT55 used. Tony's comment does sound plausible; I
distinctly remember "electrolytic" printing technology though no details. I
wonder if it might help to take a bit of the paper to a competent chemist for
analysis, to find out what the active ingredient is. That might help give a
clue what is needed to make it work.
paul
