In article .com,
says...

my son in law was over doing some repairs, his chalk line was removed
from his toolbelt by one of the kids and chalk was released onto the
carpet (brand new mind you). Now have some red on the carpet.


Well, the different colors have different ratings, red is permanent. You can
try contacting the manufacturer. Irwin is one common company, here is a link to
their answer about chalk colors, according to them it is "nearly impossible to
remove":

http://www.irwin.com/irwin/consumer/.../irwin/consume
r/repository/AskIrwinRepository/BMCO_0130Chalk.xml&asked=yes

--
Dennis