Rubber trim is shedding black gook -- will Mother's seal it up?

The rubber trim around the windows of my 95 XT is starting to shed black gook. After washing the truck, I can run a rag across the rubber trim and it comes away black. Also, the black stuff is faintly streaking the paint on the body panels below the windows after a wash. I've seen a lot of good words in this forum about Mother's Back to Black softening and restoring color. Will Mother's seal the rubber and stop it from shedding? Is there anything else I should do? Thanks for any advice -- this seems to be a common problem with weather-worn rubber trim.

 

[Bill Kemp]

I use 303 Areospace stuff on the rubber trim. I think you will always get some black on a towel after washing & wiping the rubber. 303 lasts a couple of weeks and doesnt run off after a rain.

 

[HardTech]

new 05 car puts black stuff on the drying towel... so its perfectly normal. Every car I have ever had has done this. The only time something didnt do this, the rubber was all dry and cracked falling apart. So I take this as a normal sign.

As for the run off after it rains though, im sure waxing it will help it. but the black marks when rubbing something over it will always happen

 

[rookieshooter]

Just did a search on the 303 sounds good. Going to try it on the old B11 rubber gaskets and on the wiper blades of the Ex.