Infinity Kappa 6.2i

When I took my covered Infinity Kappa 6.2i out of the cellar after 11 years, I noticed that the Polydome membrane was no longer transparent, but now yellow.After I had overcome my first shock, I decided to carefully remove the midrange driver and take it apart, since the coating could not be removed from the outside. The disassembly of the dome caused no difficulties (screwed). The ugly coating was on the inside of the dome and could be cleaned carefully with spirit and a cotton pad. A breath silicone spray and the calotte shone in new gloss. The "repair" of the second dome took 10 minutes. Since 2 months the box hangs again at the amplifier and still looks like on the day of the repair. All the expensive Kappas here on the net have the problem and nobody dares to use the allen key. Where does the yellow on the inside actually come from?