Cleaning the carb valves

Does anybody have a safe method for cleaning carb valves?

I just finally got to pulling the carbs off my ‘83 Spectre. They were the last component I’m planning to remove this season and upon inspection I noticed the valves seemed a little sticky. I took the caps off and pulled them out to find that they have a sort of matte coating on them that is sticky and roughed up in some places. It comes off on in a black dust on my thumbnail if I scrape it. Beneath it there looks to be a smooth shinier black surface.

Having never touch a carb before, I want to proceed with the utmost caution. I know carb cleaner isn’t safe around rubber and so I don’t think I want to get it anywhere near these.

Has anyone else seen this type of buildup before? My real fear is that what I’m seeing is a delamination of a necessary coating on the valves and that they are shot and not inexpensive to replace.

I’ll add photos below.

All the best,
Brion


 

What I do is spray carb cleaner on a rag and rub down the slides to remove the grunge.  It's good to keep the carb spray off the diaphragms, but a little incidental contact won't hurt anything.