Plastic discolouration

[RideTheCrash]

I already sort of know the answer to this, but I was wondering if anyone else has ever seen this. I use an old live mixer that has been all over North America (before I owned it) and the plastic knobs have discoloration on certain sides of the knobs that would have been touched the most, or the discolouration is sometimes in the form of spots.

I know plastic can get discoloured from being exposed to the sun, but I suppose it's possible from just being touched with dirty hands for...oh, 24 years? I just don't get the spots bit. I'm currently just cleaning the knobs with some dish soap and warm water but as I figured, it has no effect on it. Doesn't bother me really, just found it weird.

 

[scrubs]

Now you can call it vintage and sell it for 3x as much.

 

[RideTheCrash]

This board? Hardly, haha.

On some really bad knobs it's almost like there is a bubbling or something going. Like something is caked on or it's the plastic itself, it's kind of bizarre.