Homebrew PCBs

At 7:26 am ((PDT)) Sun Sep 2, 2007, in Digest 2274 Stefan Trethan wrote:
>On 9/2/07, Mr Crazy <crazymr420@...> wrote:
> > Does any one know if OHP film, Transperancy and Acetate Films
> > are the same or all are different?[snip]
>
>I'm not sure if any of the above is ideal for TT (i consider them one
>and the same BTW).

Some years ago, at the college where I then taught computing, so
did some of the newly (but partially) computer-literate teaching staff.

As they began to word-process their classroom presentations and
sought to emulate more knowledgeable staff who were printing direct
to OHP slides or photocopying printed copy**, they discovered
the hard way that the _acetate_ film on which they had been used to
hand-draw was inadequate.

The least-bad outcome was that the sheet cockled in the printer
or photocopier and the result was probably unusable.

The worst outcome was that the sheet never emerged - it had
wrapped itself into a heat sealed tube around one of the fuser
rollers and the printer or copier would be out of action until
a technician could find the time to dismantle it.

[** We found that a denser projection image could be obtained
by photocopying paper printouts than by laser printing directly.
The laser printers of the time couldn't transfer as much toner to
plastic film as they could to paper, while the copiers had no
problem making a dense copy onto film.]

Later, we had another (but less disastrous) learning experience
when new-model fuser temperatures went up and some
photocopier transparency film proved insufficiently heat resistant
and was likely to distort during printing. ISTR that some types
of film had a temporary paper backing sheet which made them
behave better than un-backed ones - and there was a warning
on the pack not to remove the backing before printing.

'Acetate' is an old term for old material which may still be available.
Don't specify it and don't try to put it through a laser printer.


Regards, LenW