I would like to find a chemical that will trigger the color in
Crayola's Color Wonder product.

The answer to this earlier question may be of interest to you:

http://answers.google.com/answers/threadview?id=323733

That question lead me to purchase the color wonder set. The products
is very good. So good that I can not get the color to appear on any
surface other than the one provided. I am looking for a chemical that
will trigger the color.

As mentioned in the answer to which I linked above, the product is
based upon a proprietary formula whose ingredients have not been made
public. Have you tried experimenting with simple household acids and
bases such as vinegar and ammonia?

Cheap chemistry sets and magic sets demonstrate several colors from
colorless chemicals ie sodium ferocyanide and iron sulphate produce a
deep blue. Phenolthaline produces a pink color with any alkali which
returns to colorless when nuetralzed with an acid, and litmus paper
and some dyes change color when made slightly acid or slightly alkali.
  Neil

Marking systems which are non-staining to household items, non-toxic,
and easily removable.     Kaiser, Richard J.; Urbanski, Arthur N. 
(Binney & Smith Inc., USA).    U.S.  (2000),     9 pp.  Application:
US  98-108526  19980701



The marking system comprises a marking compn. comprising ³1 color
precursor as a leuco dye.  A marking instrument can be used to store
the marking compn. and/or apply the marking compn. to a desired
substrate.  The substrate is provided with a coating comprising ³1
color-triggering developer.  Upon application of the leuco dye to the
substrate, a chromophore, and hence, color, is formed.  If, however,
color is inadvertently triggered on an unintended surface e.g.
household item, resulting in an unwanted stain, the stain can be
readily removed.

:)  You can read all about it in the patent app if you wish, but I
would be willing to bet you nickel that it will cost you more to
figure it out than if you just keep shelling out the bucks for the
markers.

Chugs,

Bob