how do you clean the rubber area?

I have some white stuff (don't know what it is) on the rubber part of the lens where you focus or zoom the lens....

what should I clean that rubber area with? I don't think a q-tip is going to do the job because I tried rubbing it with my fingers and it's still stuck on there... Are there some sort of solution that will clean it?

Lighter fluid works well and is inexpensive.

Professor wrote in post #9696621
Lighter fluid works well and is inexpensive.

are you kidding? Seems like a good way to chemically attack the lubricants in the lens itself.

Maybe a soft bristled toothbrush?

Armor All. Very light coat. Spray on a rag and then use the rag. Don't spray on the lens itself.

I had a lens where the rubber turns grey, and I did some research. You can use Silicone based lubricant on rubber, DON'T use any petroleum based lubricant. I got a can of silicone lubricant from hardware store, spray on q tip, and apply on the rubber part, so far so good.

I just used a soft brush and wet it a little, it works for me.

I wouldn't use silicone spray on the rubber. It is good for the rubber yes, but makes your lenses slippery and a touch greasy.

I use "Endust for Electronics" for cleaning, sprayed on a microfiber cloth. Removes any dirt, dust or that white oxidation leaving a fresh, satin finish with no film or residue. It doesn't list ingredients, but it's oil, ammonia and wax free - and also eliminates static.