31 Jan
2010
31 Jan
'10
9:11 p.m.
Dave McGuire wrote:
Indeed. Many older (HP) calculators used thermal paper. It'sa good idea
to make photocopies (or I guess scans these days) of any printouts you
want to keep.
It's not generally realsied that themral printouts fade with time. I was
chatting to somebody from a major museum and he didn't realise the
historically-significant calculator printouts needed to be copied _NOW_.
Dedicated thermal receipt printers are nice,
but from what I've heard
they're not as reliable as dot-matrix impact printers in the field.
That seems odd to me, but I guess the heating elements dying does make
some sense.
There's one major issue with direct thermal: ink fade. Basically the printing fades over time. Some retailers love this,
because after about
8 months the receipt is basically blank -- "Sir, we'd be happy to accept
that under the 12-month guarantee, but we need a receipt -- not a blank
strip of paper."
For bonus points: heat and light make it fade quicker. Leave a
thermal-print receipt on a windowsill on the 1st of the month and it'll
be blank by the end of the month. Leave it on or near a radiator and
it'll go completely black within a few minutes.
Needless to say a soldering iron works just as well. I've been known to
use one to check if the paper is still thermally sensitive, and to see
which is the sensitive side.
There are also significant chemical compatibility
issues. Most notably,
Propan-2-ol will darken most thermal paper, as I fopudn out the hard way
when clening a bit of hardware with said solvent and some othe spray
landed on some printouts from my LogicDart (it uses the HP82440 IR
thermal printer)..
applying a strip of Sellotape to a thermal-printed
slip/receipt causes
Pehaps I've been lucky,but I've not had any prolems sticking down HP
calculator printouts with 3M 'magic tape' onto a piece of plain paper to
make them easier to copy.
[...]
-tony