I just discovered that the silicone sleeve on my wacom pen has degraded, becoming oily and sticky. It's been on my desk in front of a window, so it's probably down to the UV light.
I took the rubber grip off (unscrew the end with the ID collar and it should slide off) and tried washing it in hot soapy water, which just made it wet and didn't do anything. In fact it made it worse, since it just got covered in bits of fluff off the (now oily) cloth that I used to dry it.
But, if you ignore what you read online, ALCOHOL IS THE SOLUTION!
Give it a wash in alcohol hand gel and it's restored it very well. I've thrown away a Fitbit smart watch and PC mouse because the silicone's degraded the same way.
When you're not using the pen, keep it in a drawer or bag or somewhere out of sunlight. These things are eyewateringly expensive at £65+ and for the sake of a rubber sleeve, no matter how well you look after your stuff, if you don't know it could be an expensive lesson, but since almost everyone has alcohol hand wash now, it's something to bear in mind.
😁