Tile Identification Each TPS tile has an identification code that is painted in yellow. The paint does not burn off during entry and can be obtained commerically under the name Spearex.
Flags and letters are painted on the orbiter with a Dow Corning 3140 silicon-base material colored by adding pigments. It is basically the same paint used to paint automobile engines and will break down in temperature ranges between 800 to 1,000 F.
After each flight, the orbiter thermal protection system is rewaterproofed. Dimethylethoxysilane is injected into each tile through an existing hole in the surface coating with a needleless gun, and the AFRSI blankets are injected with DMES from a needle gun.