How do dry erase inks and surfaces work?

I am looking for a scientific explanation of how dry erase markers
work.  I need to answer questions like


1. Why do they work on some surfaces and not others?"  
2. What are the characterisitcs of the surface that make it work?
3. What are the characteristics of the inks that make it work?

My current understanding is that it has something to do with surface
tension but I do not really understand beyond that.

I want names of chemicals, substrates, and a technical explanation for
why they work together well.  I would like to know different materials
that will work and why also different inks that will work and why.

I started to answer this question, and realized I have no prrof to
bhack up my statements.  I can answer the three questions, and I will
here. Perhaps someone else can provide more substantial backing to
assist.

I hate when I hit enter before i'm finished...LOL

anyway...back to the comment.

Question :
1. Why do they work on some surfaces and not others?"  
Dry Erase markers are designed specifically to dry quickly on non
porous materials so that they don't sink into the material. A normal
magic marker ink soaks into the surface and becomes permanant based on
depth of penetration. Dry Erase is designed to dry faster and therefor
not penetrate. Using non porous surfaces makes it impossible to
penetrate and easy to clean.


2. What are the characterisitcs of the surface that make it work?
The surface as mentioned in answer 1 must be non porous, otherwise it
will penetrate prior to drying. Items like cloth, silly example but
obvious. Dry erase markers make horrible stains on cloth because they
are able to penetrate into the cloth and dry immediately.

3. What are the characteristics of the inks that make it work?
The ink has chemicals added to it which evaporate rapidly, leaving
only dried ink on the surface. This works especially well on non
porous materials such as glass. Chemicals like ketones and benzynes
are generally used for this purpose based on their evaporation rate.

As a link to the chemical compounds used in the inks, please see:
Silverchips Online Newspaper
Montgomery Blair High Schools Online Newspaper.
Markers To Be Replaced November 1998 by Michelle Clive 
http://silverchips.mbhs.edu/silverchips/nov98/news/markers.html

"Chemistry teacher Tran Pham performed a chemical analysis on the Expo
brand marker fluid and the solvent used for erasing wipes and found
that they primarily contained chemicals in the ketone and benzyne
groups."


"Pham found that the Expo solvent contained toluene and benzyne, which
he said are "priority pollutants classified by the EPA.""


Search Engine Used: GOOGLE.COM of course
Keywords:dry erase markers toluene


Mother911-ga

p.s. Toluene is used in making paints, paint thinners, fingernail
polish, and lacquers. It is a by product of gasoline production from
crude oil.

I appreciate the attempt, but as you stated I do need some evidence to
back it up, also I am not convinced this answer is correct, let me
explain.

In the first response
"1. Why do they work on some surfaces and not others?"  
Dry Erase markers are designed specifically to dry quickly on non
porous materials so that they don't sink into the material. 

My Comment
There are several non-porus surfaces that do not work as dry erase
surfaces.  Two examples I tried in my own experiments are the glass
from the monitor of my computer and a clear polyester container from
the grocery store that held a salad.  In both cases the ink smeared
and left a sticky residue when "wipped off"


"The surface as mentioned in answer 1 must be non porous,"

My Comment 
See above


"What are the characteristics of the inks that make it work?
The ink has chemicals added to it which evaporate rapidly, leaving
only dried ink on the surface. This works especially well on non
porous materials such as glass. Chemicals like ketones and benzynes
are generally used for this purpose based on their evaporation rate."

This makes some sense, possibly why the markers smell funny and dry
out quickly, however I need some more concretes.  Can you add an
evaoporative chemical to any kind of ink?  Also I noticed on the
Sanford EXPO markers it conforms to ASTM D-4236.  I didn't search on
this but I am assuming it is an standard for hazardous chemicals to be
non-toxic.  Also on the marker it says "For use on most dry erase
surfaces".  My question is "why most" what is the scientific
explanation for why it is working and why it wouldn't work other
places?

One other clue I found is on the EXPO it says "Recap and keep
horizontal when not in use".  I wonder why you need to keep it
horizontal, maybe this has something to do with the evaporation?

I really need more of the technical details of how it works answered.

Hi Curiosguy2003,

more thoughts:
"Two examples I tried in my own experiments are the glass
from the monitor of my computer and a clear polyester container from
the grocery store that held a salad.  In both cases the ink smeared
and left a sticky residue when "wipped off""

I think the sticky residue is actually the dried ink. I wish it was
easier to sift through the hundreds of results for dry erase marker
sales on the web to get more info, you've got my mind spinning on this
one.


"Can you add an evaoporative chemical to any kind of ink?"  
I would imagine the answer is no. If you could, we would have a more
diverse dry-erase market.

"Also I noticed on the Sanford EXPO markers it conforms to ASTM
D-4236. I didn't search on this but I am assuming it is an standard
for hazardous chemicals to be non-toxic."

In the article from the Silverchips.NBHS.com website, it mentions that:

"Pham explained that the markers can be labeled non-toxic because they
do not have a high enough concentration of chemicals to affect a
person's health immediately."

"Recap and keep horizontal when not in use".  
Re-capping keeps the ink from drying out in the pen capsule, storing
it horizontally prevents pooling of the ink which in most cases is
stored by soaking a porous material in ink. If it stood on end, the
ink would theoretically pool at the bottom of the pen rendering it
useless.


Mother911