Found a great pen to mark HP calculator cards
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07-29-2022, 12:28 PM
Post: #7
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RE: Found a great pen to mark HP calculator cards
(07-27-2022 07:31 PM)ijabbott Wrote: The other nice thing about these pens is they use a bistable invisible ink. Heating the ink up by friction (using the "eraser" at the end of the pen) turns it transparent. Cooling it below -10C for a while turns it visible again! Interesting. I knew about the friction part "erasing" the ink. Didn't realize it would come back by freezing it. |
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Messages In This Thread |
Found a great pen to mark HP calculator cards - Xorand - 07-01-2022, 01:08 AM
RE: Found a great pen to mark 41C/67 cards - teenix - 07-02-2022, 12:00 AM
RE: Found a great pen to mark 41C/67 cards - Xorand - 07-02-2022, 01:38 AM
RE: Found a great pen to mark 41C/67 cards - Massimo Gnerucci - 07-02-2022, 08:36 AM
RE: Found a great pen to mark 41C/67 cards - Xorand - 07-03-2022, 09:52 PM
RE: Found a great pen to mark HP calculator cards - ijabbott - 07-27-2022, 07:31 PM
RE: Found a great pen to mark HP calculator cards - Xorand - 07-29-2022 12:28 PM
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