# Chalk on Glass **URL:** \ **Category:** Factual Questions\ **Created:** [February 15, 2006, 7:51am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609 "2006-02-15T07:51:36Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![Ronny](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@Ronny](https://boards.straightdope.com/u/Ronny)\ **Post date:** [February 15, 2006, 7:51am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/1 "2006-02-15T07:51:36Z")
in the movie “a beautiful mind” how does John Nash (played by Russel Crow) manage to draw his questions on his glass window using what looks (and based on the time period) to be normal chalk? if you’ve every tried it, it doesn’t come out as well as the movie makes it out to be. also, the principle behind a chalk stick is friction, which a glass window would be lacking in. any ideas? thanks. Ronny. ---
**Author:** ![Palooka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/palooka/32/2902_2.png) [@Palooka](https://boards.straightdope.com/u/Palooka)\ **Post date:** [February 15, 2006, 8:00am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/2 "2006-02-15T08:00:59Z")
He’s using a worn down grease pencil. ---
**Author:** ![Ronny](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@Ronny](https://boards.straightdope.com/u/Ronny)\ **Post date:** [February 15, 2006, 8:05am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/3 "2006-02-15T08:05:00Z")
thanks for the quick response. what he’s holding looks alot like chalk though. and i don’t think grease pencils write in white do they? ---
**Author:** ![Ronny](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@Ronny](https://boards.straightdope.com/u/Ronny)\ **Post date:** [February 15, 2006, 8:08am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/4 "2006-02-15T08:08:45Z")
i mean, in that time period. and his location. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 15, 2006, 8:31am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/5 "2006-02-15T08:31:04Z")
Chinagraph pencils have been around for quite a while, I think. ---
**Author:** ![daffyduck](https://avatars.discourse-cdn.com/v4/letter/d/ec9cab/32.png) [@daffyduck](https://boards.straightdope.com/u/daffyduck)\ **Post date:** [February 15, 2006, 8:37am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/6 "2006-02-15T08:37:28Z")
It is really quite simple… he’s using Hollywood chalk. The actor may, indeed, actually be holding a piece of chalk and the marks made by it added in post production, or it could very well be a grease pencil made to look like a piece of chalk by a special effects guy or it could even be liquid paper in a device made to look like a piece of chalk. The scene was shot for the visual impact, not to document an actual event. ---
**Author:** ![Ronny](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@Ronny](https://boards.straightdope.com/u/Ronny)\ **Post date:** [February 15, 2006, 8:43am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/7 "2006-02-15T08:43:18Z")
hi daffy. yup that does make alot of sense. to use a grease pencil to draw all the equations, and shot the actor holding a piece of chalk. but at one point they show him actually drawing on the glass. CGI could do that, but would they really spend the money to CGI something like that? it just looks so much like chalk… but i guess it has to be some kind of grease pencil. the movie aside, did John Nash (or anyone else for that matter) actually use their windows as chalk boards? it seems like a good idea for the time period, i’m sure john nash in the movie wasn’t the first man to ever try it. and if someone else did it in real life, what did they use? a grease pencil? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 15, 2006, 8:48am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/8 "2006-02-15T08:48:30Z")
Further research appears to place the invention of grease pencils (of some kind) more than 200 years ago; they were/are used in a printing process called stone lithography, invented by Senfelder in 1798. ---
**Author:** ![Palooka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/palooka/32/2902_2.png) [@Palooka](https://boards.straightdope.com/u/Palooka)\ **Post date:** [February 15, 2006, 9:13am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/9 "2006-02-15T09:13:44Z")
Alright, I’m having trouble capturing the image since my good media players don’t want to run the DVD and WMP crashes when I kill hardware acceleration, but at 6:18 there is a close up of the object he uses to write on the windows. It doesn’t look anything like chalk. It’s definitely a grease pencil. ---
**Author:** ![Ronny](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@Ronny](https://boards.straightdope.com/u/Ronny)\ **Post date:** [February 15, 2006, 9:23am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/10 "2006-02-15T09:23:19Z")
all right. i don’t have a copy with me now to check it out properly, but that’s gotta be it then. grease pencil. thanks for the dedication to helping answer the question. i appreciate it. really. its been bugging me since it first came out. thanks again. Ronny. ---
**Author:** ![Palooka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/palooka/32/2902_2.png) [@Palooka](https://boards.straightdope.com/u/Palooka)\ **Post date:** [February 15, 2006, 9:26am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/11 "2006-02-15T09:26:34Z")
[I got it work.](http://img45.imageshack.us/img45/9744/vlcsnap125676sg.png) Definitely not chalk. ---
**Author:** ![Ronny](https://avatars.discourse-cdn.com/v4/letter/r/94ad74/32.png) [@Ronny](https://boards.straightdope.com/u/Ronny)\ **Post date:** [February 15, 2006, 9:44am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/12 "2006-02-15T09:44:40Z")
yup thanks a bunch for clearing THAT up. whew. ---
**Author:** ![Lynn\_Bodoni](https://avatars.discourse-cdn.com/v4/letter/l/e47c2d/32.png) [@Lynn\_Bodoni](https://boards.straightdope.com/u/Lynn_Bodoni)\ **Post date:** [February 15, 2006, 1:36pm UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/13 "2006-02-15T13:36:16Z")
> [@Ronny](#): > > the movie aside, did John Nash (or anyone else for that matter) actually use their windows as chalk boards? it seems like a good idea for the time period, i’m sure john nash in the movie wasn’t the first man to ever try it. and if someone else did it in real life, what did they use? a grease pencil? I’ve used grease pencils to make notes on my computer monitors. When I played M.U.L.E., for instance, I’d mark the squares that had been assayed for Crystite ore. Or I used a grease pencil to write the password for a game. Grease pencils/china markers come (or came) in a variety of colors. The marks come right off with a little glass cleaner and a paper towel, too. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [February 15, 2006, 2:06pm UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/14 "2006-02-15T14:06:08Z")
> [@Lynn Bodoni](#): > > I’ve used grease pencils to make notes on my computer monitors. When I played M.U.L.E., for instance, I’d mark the squares that had been assayed for Crystite ore. Or I used a grease pencil to write the password for a game. Grease pencils/china markers come (or came) in a variety of colors. The marks come right off with a little glass cleaner and a paper towel, too. If you made a mistake, you didn’t use whiteout did you? ---
**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\ **Post date:** [February 15, 2006, 7:41pm UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/15 "2006-02-15T19:41:07Z")
> [@Lynn Bodoni](#): > > Grease pencils/china markers come (or came) in a variety of colors. Still do, 10 colors from [Sanford](http://sanford.com/sanford/consumer/jhtml/new-product/productlist.jhtml?_requestid=60016). Other than selling them to art students, I’ve seen them used by baggage handlers at the airport. ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [February 16, 2006, 3:30am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/16 "2006-02-16T03:30:52Z")
Ronny writes: \> the movie aside, did John Nash (or anyone else for that matter) actually use \> their windows as chalk boards? it seems like a good idea for the time period, i’m \> sure john nash in the movie wasn’t the first man to ever try it. and if someone \> else did it in real life, what did they use? a grease pencil? The movie _A Beautiful Mind_ was full of entirely made-up scenes, characters, and situations. ---
**Author:** ![Whammo](https://avatars.discourse-cdn.com/v4/letter/w/8dc957/32.png) [@Whammo](https://boards.straightdope.com/u/Whammo)\ **Post date:** [February 16, 2006, 3:45am UTC](https://boards.straightdope.com/t/chalk-on-glass/344609/17 "2006-02-16T03:45:07Z")
Palooka got it work!