Mike Bailey on wed 8 sep 99
Hi all,
Firstly, thanks to Martin Howard for getting the analysis of some
photocopier powder.
Secondly, this remided me of a decorative technique shown at the
Aberystwyth Potters Camp this summer. The basic idea was to use a
photocopier in the usual way to produce an image - however, by disabling
the heating bit that fixes the powder it is possible to transfer the
powdery photocopied image on to a piece of leather hard clay by simply
putting it face down on the clay and rubbing.
I expect most of you have heard of this but thought I'd share it in case
it catches anyones interest. With Martin's useful analysis we can see
why it works as an underglaze colour. I do remember that apparently not
all powders are suitable and that some makes work better than others.
Cheers,
Mike.
--
Mike Bailey
Gail Phillips on fri 10 sep 99
Let's see if I can explain this - I work on microfilm reader-printers,
which operate much the same as copy machines.
The drum which receives the image through light shining through the film
directed by mirrors is photosensitive. This "imprints" the area which will
receive toner. The drum rotates, passing electrically charged corona wires,
which ionize the drum surface. Toner is mixed with developer at a set ratio
in the developer assembly, which consists of a trough of developer (ferrite
powder), a roller that has a magnet set a particular angle running inside
the length of it, and some other stuff unimportant to this discussion. The
toner-developer mixture sticks out in a brushlike fashion at the proper
angle to allow the toner particles (which are oppositely charged
electrically) to make the jump to the drum. The developer stays behind -
when I change developer in a machine, I always have the same amount of old
dumped out of the machine as of new that I put in, and I can tell, because I
refill the new empty jar with the old stuff to throw it away. The toner
gets transferred to the paper using another corona wire changing the
polarity to make the toner leave the drum for the more electrically
attractive paper. The paper then passes through the fuser, which is very
hot, and that melts the toner to the paper. I can't help but think that
toner is a form of plastic. I have heard, but do not know how true it is,
that exposure to a lot of toner is not a great idea, as it is carcinogenic.
It is very lightweight, and is easily made airborne. You don't always see
it, either. Monona Rossol, how about it?
- Gail Phillips
potter and Imation service technician
Martin Howard wrote:
> ----------------------------Original message----------------------------
> Steady Mike Bailey. You are making the error of mixing Toner with
> Developer.
> It is the Toner which is fixed or not fixed onto the image. That is
> almost pure carbon. Ideal for copying images and for using as a local
> reduction agent.
>
> The Developer, the ferrite powder we have been discussing with Ricoh,
> stays inside the machine and just gets somewhat contaminated over a
> period of time. The engineers will then replace it for new and usually
> just throw the old away, unless a potter is nearby.
>
> Of course, it may be that some copiers work differently from others and
> we are getting some with Developer on the final copy. Someone should do
> a survey of them all and find out which are which. Is there someone out
> there wanting a PhD subject?
>
> Martin Howard
> Webbs Cottage Pottery and Press
> Woolpits Road, Great Saling
> BRAINTREE
> Essex CM7 5DZ
> 01371 850 423
> araneajo@gn.apc.org
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