MadSci Network: Chemistry

Re: What is the different chemical in Permanent markers than dry erase?

Date: Mon Oct 16 14:44:56 2000
Posted By: Keith Allison, , dept: New Product, Technology & Development, Binney & Smith, Inc. (Crayola)
Area of science: Chemistry
ID: 970339027.Ch

Dear Katie,
     The difference between a permanent and a dry-erase marker is small.  
Actually, a dry-erase marker IS a permanent marker on any surface that is 
porous (like paper) as opposed to glass, metal, some plastics, and dry-
erase boards (whiteboards).  When comparing both types of ink, the dry-
erase ink has the same basic ingredients as the permanent type: colored 
pigments, "carrier" (water, alcohol or another solvent) and polymer.  The 
difference lies in which polymer is used: for permanent markers, acrylic 
polymers are often used...these polymers are also used in house paints to 
make the pigment stick to the walls.  For dry-erase markers, an oily 
silicone polymer ("release agent") is added; the oily film it makes serves 
as a lubricating barrier that keeps the colored pigment from touching and 
staining the whiteboard. The silicone polymer is so slippery that it just 
slides off of the whiteboard, taking the pigment with it.
     So, in order to make a dry-erase marker ink permanent ON A 
WHITEBOARD, a polymer must be added to make the pigment stick, such as I 
described earlier that acts like a glue for nonporous surfaces like 

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