DuPont Yellow Tychem QC Chemical Protection Coveralls With Serged Seams, Front Zipper Closure, Attached Hood, Elastic Face, Ankles and Wrists. DuPont Tychem QC fabric starts with Tyvek brand fabric and adds a polyethylene coating for added chemical protection. Tychem QC fabrics are tested by a third party laboratory to assess its chemical permeation resistance. DuPont has data for over 80 chemicals for Tychem QC in SafeSPEC 2.0 so that the user can select an appropriate garment. Apparel made from Tychem QC is lightweight and durable.