# How do carbonless forms work?

**URL:** <https://boards.straightdope.com/t/how-do-carbonless-forms-work/320767>\
**Category:** Factual Questions\
**Created:** [September 9, 2005, 2:35am UTC](https://boards.straightdope.com/t/how-do-carbonless-forms-work/320767 "2005-09-09T02:35:28Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Otto](https://avatars.discourse-cdn.com/v4/letter/o/bbe5ce/32.png) [@Otto](https://boards.straightdope.com/u/Otto)\
**Post date:** [September 9, 2005, 2:35am UTC](https://boards.straightdope.com/t/how-do-carbonless-forms-work/320767/1 "2005-09-09T02:35:28Z")

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You know, like double checks or three-sheet invoices where you keep the white copy, the pink copy gets attached to the package and the yellow copy goes inter-office mail to Jerry in billing? How do the words appear on the bottom copy/ies?

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**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [September 9, 2005, 2:41am UTC](https://boards.straightdope.com/t/how-do-carbonless-forms-work/320767/2 "2005-09-09T02:41:43Z")

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There are microencapsulated dyes deposited on the back surface of the paper. On the front surfaces of the copy forms is deposited a reactive clay powder. Pressure from the pen breaks open the microcapsules, and the released dye reacts with the clay to form a permanent, dry mark.

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**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [September 9, 2005, 2:43am UTC](https://boards.straightdope.com/t/how-do-carbonless-forms-work/320767/3 "2005-09-09T02:43:13Z")

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[Wikipedia](http://en.wikipedia.org/wiki/Carbonless_form) has a nice diagram to illustrate, in case my description wasn’t clear enough.