"Chemical milling maskant" means a coating that is applied directly to aluminum components to protect surface areas when chemical milling the component with a Type I or II etchant. Type I chemical milling maskants are used with a Type I etchant and Type II chemical milling maskants are used with a Type II etchant. This definition does not include:
bonding maskants;
critical use and line sealer maskants;
seal coat maskants;
maskants that must be used with a combination of Type I or II etchants and any of these maskants (i.e., bonding, critical use and line sealer, and seal coat); or
maskants that are listed as aerospace specialty coatings in 35 Ill. Adm. Code 219.204(r)(2).
Ill. Admin. Code tit. 35, § 211.985