Liquid Chalk markings come off with a quick wipe from a damp cloth, yet they are waterproof and
permanent under the heaviest rainfall. 

• Liquid Chalk markings come off with a quick wipe from a damp cloth, yet they are waterproof and
  permanent under the heaviest rainfall.  Liquid Chalk will not even come off under direct spray from a pressure hose!  Sounds impossible doesn't it?  This makes Liquid Chalk ideal for almost any garden
  or greenhouse application.  Under dry conditions the markings will not come off if rubbed or
  subjected to light abrasion.

• IS LIQUID CHALK TOXIC?
  No!  Liquid Chalk is water based, completely odor free and certified as Non Toxic under the terms of
  ASTM D 4236 in accordance with Federal Law.  This means they are completely safe for use by adults
  and childen.  Equally as important, Liquid Chalk requires no solvent based cleaners to ensure complete
  removal.  A simple wipe with a wet cloth is all that is required to remove markings from any non-porous
  surface.