Abstract: An improved chemical wash is used to cleanse the interior of an open Cathode Ray Tube (“CRT”) funnel before a coating of a carbon material is applied. The traditional ammonium bifloride wash for CRT funnels can be replaced with an aqueous solution of trisodium phosphate (“TSP”). The TSP solution is preferably sprayed under pressure into the open CRT funnels to cleanse each funnel before the interior coating of carbon material is applied. The TSP solution cleanses the funnels as well as the ammonium bifloride wash previously used, but does not tend to clog the wash sprayers. Moreover, the TSP solution does not need to be treated before it is released as waste and costs significantly less that the previous ammonium bifloride wash.