# Psst! Secret codes and invisible inks
**URL:** https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230
**Category:** Miscellaneous and Personal Stuff I Must Share
**Created:** [June 9, 2009, 6:40pm UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230 "2009-06-09T18:40:42Z")
**Posts on this page:** 7
**Page:** 3
### Author:  [@aruvqan](https://boards.straightdope.com/u/aruvqan)
#### Post date: [June 12, 2009, 7:22pm UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/41 "2009-06-12T19:22:54Z")
> [@Eureka](#):
>
> This may seem off topic, but it might be fun for 8 year olds.
>
> My latest knitting project is illusion knitting (also called shadow knitting) The idea is that you use two colors of yarn and a pattern of knits and purls to create a message–usually an image–only visible at an angle. When viewed straight on, it’s a simple stripe, but at an angle, you can see kitty cats and witches hats, and all kinds of stuff.
>
> This blog entry shows the idea with legos, which might be fun for eight year olds to play with.
> http://sgknitting.blogspot.com/2008/01/shadow-knitting-with-legos.html
that didnt work, i suggest [http://sgknitting.blogspot.com/](http://sgknitting.blogspot.com/) and scroll down. that link goes to legos 404 page
---
### Author:  [@constanze](https://boards.straightdope.com/u/constanze)
#### Post date: [June 12, 2009, 7:50pm UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/42 "2009-06-12T19:50:44Z")
> [@shantih](#):
>
> Well, I met with the other parents working on this project, and I’ve worked out a plan for my part. As it turns out, the kids will be solving a case on the fourth project day, so I only needed to plan ideas for three days, which was unexpectedly painful – I found so many cool codes and tricks that I could have easily filled the week!
Sounds like an interesting and yet achievable plan. But since you seem to have licked blood now, nobody is stopping you from offering extra afternoons at your house in the summer holidays for those kids who catch fire, right? (If you have the time and inclination to continue - but it does sound like fun, and with nice kids…)
> [@](#):
>
> If you all like, I’ll update at the end of next week with how it all went. It would be bad manners to put that post in code, right? 🆒
Of course we are all eagerly awaiting your tales of daring-doo!
---
### Author:  [@Otanx](https://boards.straightdope.com/u/Otanx)
#### Post date: [June 13, 2009, 8:15am UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/43 "2009-06-13T08:15:49Z")
> [@shantih](#):
>
> Day 2
> Invisible ink: revealing the messages of the first day by ironing them or holding them over a light bulb. Writing new secret messages in lemon juice between the double-spaced lines of a harmless text or on the envelope of a letter, and indicating where to look by the phrasing of the header (“Dear Reader” to look on the letter itself, and “Hello Reader” to look on the envelope). (Thanks, **Otanx**!)
Not a problem. I wish I was young enough to go to your class.
> [@](#):
>
> I’m still trying to find a way to work in the trick of writing a brief message on a tiny sheet of paper which is then hidden on the underside of a stamp or a sticker, but I have to let the others have a bit of time for their own parts, I suppose.
Write on the paper, put the stamp/sticker over it. Stamp/sticker must be steamed off to read. Reader knows it is their because of the orientation of the stamp/sticker(i.e. stamp is upside down there is a message). This can also be used instead of the greeting from my example above. 90 degrees to the right, hidden on envolope, 90 to the left, on the letter.
-Otanx
---
### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [June 13, 2009, 4:08pm UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/44 "2009-06-13T16:08:09Z")
> [@shantih](#):
>
> Secret code: [Code wheels](http://home.howstuffworks.com/make-games13.htm)…
Don’t they all just say “Drink more Ovaltine”?
---
### Author:  [@shantih](https://boards.straightdope.com/u/shantih)
#### Post date: [June 13, 2009, 4:49pm UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/45 "2009-06-13T16:49:00Z")
> [@beowulff](#):
>
> don’t they all just say “drink more ovaltine”?
Shhhhhhhhhhhhh!!
🙂
---
### Author:  [@shantih](https://boards.straightdope.com/u/shantih)
#### Post date: [June 18, 2009, 11:32am UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/46 "2009-06-18T11:32:33Z")
The project week is almost over, so here is an update as to how it actually worked out.
I wasn’t there on Tuesday, the first day of the project, but the others showed the kids how to write messages with lemon juice. Very fine, and only one minor fillip: in holding the paper over a candle to make the lemon juice visible, one kid caught his message on fire and dropped it on the carpet, where it was stamped out. It does not show my most mature side that I snickered every time I saw the dark smudge, right?
The time just flew by each day, so I ended up cutting out almost half of what I had planned. We didn’t bother to do anything more with invisible inks after that first day (although I brought my iron along yesterday and today for safety’s sake), but I showed all three groups the letter pairs code, which they picked up right away, and we made code wheels, and today I showed them the grid code and gave them new messages in the letter pairs code.
Tomorrow will be the big day: they’ll have a case to solve, with fingerprints, footprints, a coded message, and other clues to detect.
And now I’m off to shower off the grubbiness of the morning – another mother and I were shadowed by the kids as we walked along different streets, exchanged cloth bags, exchanged a newspaper on a bench, and left a coded message at a dead drop (a matchbox hidden under the bench).
The decoded message, by the way, reads: “Careful! The kid next to you might be a spy!” 😛
And if I haven’t already made it clear, this has been the most funnest week EVER.
---
### Author:  [@Shot\_From\_Guns](https://boards.straightdope.com/u/Shot_From_Guns)
#### Post date: [June 18, 2009, 3:25pm UTC](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230/47 "2009-06-18T15:25:20Z")
Whee! Keep it comin’, **shantih**!
[Previous page](https://boards.straightdope.com/t/psst-secret-codes-and-invisible-inks/499230.md?page=2)