Optical coatings formulations containing tetrafluoroethylene

Two optical reference coatings containing tetrafluorethylene have been formulated using silicone binders. One of the silicones used is an oligomer of methyl silanol supplied at 48 percent solids in a mixture of butanol and ethanol. The other silicone is a proprietory silicone tethered ethyl silicate based colloidal silica binder supplied at 22 and 36 percent solids in a mixture of low molecular weight aliphatic alcohols. The coatins are characterized by high durability and have an overall reflectance in the visible part of the spectrum of about 90 percent. The substrate preparation and application procedures are described.