In the past few months we've debunked a lot of the old dogma.After browsing through this thread, I'll add this. I've read several books on meerschaum pipes, I've spoken to several meerschaum carvers at a pipe show, and other pipe smokers with large meerschaum collections and meerschaum experience and they all said this; cake is bad for your pipe.
It's okay to have a thin layer of cake, but building up cake like you would with a briar can cause the meerschaum to crack/break over time. The cake does not add to the color as it doesn't allow for new tars and oils to reach the meerschaum and stops the meerschaum from doing what it naturally does; express the tars and oils. As the meerschaum expresses those tars and oils the beeswax that's on the pipe holds the tars and oils in allowing us to see what we call color. If you have a buildup of cake those tars and oils won't be expressed by the meerschaum properly and your pipe won't color like it should.
Other important "NO's" from the books, and carvers; never use alcohol on your meerschaum. Alcohol will stop the natural abilities of the meerschaum. Alcohol is okay on the stem, but keep it out of the shank and bowl. Do not flush water down your pipe. It can damage the meerschaum over time and not allow it to do what it needs to do naturally. Do not use pipe reamers on the bowl, as it can damage the bowl or even crack the pipe. Using a pipe knife can also cause you to cut into the meerschaum causing damage, so they're also not recommended.
As for the washer coin in the bottom of the bowl; not sure where that idea ever came from, but it's definitely a bad idea in a meerschaum. Please don't do that.
An Observation of the Coloring of Vintage Meerschaum :: Meerschaum Pipes
The modern dogma for meerschaum pipes is to keep the chamber clean as carbon buildup prevents coloring and may lead to cracked bowls. I'm going to give up that practice temporarily after noticing something about these old pieces. They're heavily colored and have quite a bit of buildup. I think...
pipesmagazine.com