Cleaning New Models of Dr Grabow Stems

[BigR]

I have a few newer Dr Grabow pipes that I smoke regularly. I have read that the stems on the newer Grabows are made from some type of plastic. My question is what is the best thing to clean these stems with? I've been using Everclear, but didn't know if the Everclear would harm the plastic over time. Also, I have older Grabows with the adjustomatic stems. Will the Everclear harm those older stems?

 

[coming to_falling too]

The newer stems probably would be best to use water and soap. I'm not sure what the older stems are made from, but if vulcanite then alcohol would be fine. If you rub the stem with your thumb vigorously and can smell rubber then it's vulcanite.