Most faceshields have standard visors which cloud up when hit by chemicals. Eventually you won't be able to see through it and will have to replace the visors.

For those of you frequently using your visors around chemicals, these faceshields offer the best protection. These chemical- and paint-resistant faceshields are coated with Silicote .6 chemical-resistant coating. This coating acts as a barrier to protect the polycarbonate from many mild acids (except hydrofluoric acid), bases and solvents. Chemicals and wet paint wipe off, leaving the shield clear. All units come with visor and ratchet-style headgear. Available with chin guard and sideshield protection plus Anti-Fog Protection.