A black layer is coated onto the filament of the indirectly heated cathode for a Cathode ray tube. It consists of a tungsten-aluminum suspension, chemically stabilised, as the heavy Tungsten particles tend to sediment, thus disturbing the coating process. The stabilisation process is realised using a chemisorbed monolayer of an aliphatic monocarboxylic acid such as stearic acid. This is covered under US-patent 4983420 (Wolfrum, Stefan M.; Ponjee, Johannes J.; Van de Poel, Angela C.L.), filed jan 8th, 1991.

Electrochemistry