I thought I'd share this for anyone who might be having problems with building a nice, thick lather.
My shaving mug is an over-sized coffee mug soup bowl. (See photo.) The inside is plain, smooth ceramic, and doesn't offer a lot of texture to help whip up the lather. So I placed a flower-shaped bathtub grip sticker on the inside bottom, and now my lathers are magnificent. At least 3x as thick and luxurious. Life is good.
Thanx,
Christopher