Lucite, Amber, Bakelite Stem restoration

[kennyjo]

I know we can soak Vulcanite stem into OxiClean or bleach for restoration.

But will that be safe to soak Lucite, Amber, Bakelite Stem into them?
I have a few new purchased meerschaum pipes whose stems are filled with a lot of tar.

Is there a good way to remove those substance easier and allow me to use less pipe cleaners?

Maybe soak them into alcohol?
Thanks