Discoloring HIPS

Hi, I am having trouble with the discoloring of white HIPS filament, when using the Zortrax Material HIPS settings.
Having always printed with ABS, I want to produce spa jet fittings so I thought I would finally try the HIPS filament for strength and particularly water resistance in a 100% density prints.
The material has been opened for a few years.
The prints come out beige with a slight rainbow effect, almost as if it is a slightly burnt, so I suspect the temperature, but obviously I can not see the settings.

I might try external materials settings with a 220 temperature.

Any thoughts out there are very much appreciated.
( Adelaide South Australia )

Hello Dean,

since the material has been opened for a few years now - it is really likely that it has absorbed moisture and lost its properties.

Still, does this problem occur with white HIPS only? Because the symptoms may indicate the printer struggles to keep the stable extrusion temperatue which may be caused by the fact that one of the consumable parts (most likely the heater&thermocouple and hotend V2) are worn-out and require replacement (ther approximate lifespan is 350/400 hours). Check all connections and ensure the screws securing the heater&thermocouple in the hotend are right.

Best regards