Name: Nick K.
Status: student
Age: 12
Location: N/A
Country: N/A
Date: 9/22/2003
Question:
How does cold water remove stains?
Replies:
Nick,
Stain removal is a matter of dissolving (loosening) the stain and then washing it off the
fabric. Cold water serves as the solvent and it works much better if it is warm rather than
cold. In warm water, the molecules are rattling around faster than they would be if the
water was cold. Faster moving molecules are better at knocking the stain material off the
fabric's fibers because (just like a moving baseball) the faster they move, the harder they
hit.
The whole process can be made even more effective if one uses a suitable soap or detergent
to assist the removal. Soaps and/or detergents are able to assist the loosening process and
also they are able to suspend the stain material so that it cannot be re-deposited on the
fabric.
A word of caution: Some stains can be "set" in the fabric and made harder to remove if hot
water is used because hot water may cause a chemical reaction to occur that binds the stain
and its reaction products to the fabric.
Regards,
ProfHoff 728
Water is a good solvent for a wide range of substances that might stain a fabric. Very
roughly speaking this solubility is independent of the temperature. However, hot water can
promote other chemical reactions between the staining substance and the fabric that causes
the staining substance to chemically bond to the fabric and so makes it more difficult to
remove. This is only a partial answer to a very complex process -- the staining of various
fabrics.
Vince Calder
Cold water does not remove stains; it merely permits the stain removing agents to work
before the stain is set by heat. Heat, such as in the form of hot water, will cause the
stain to set, and it may become permanent. Most processes for dying cloth or yarn use
heat to set the dyes, to cause them to bond permanently. A chemist can probably explain
why heat does this.
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.
