I used to do it often when I was bowl lathering. More for fun than anything else. It works.
I am, of course, mostly joking here but I do have a beard and I do take a scrap of soap to my face to build a lather. It's pretty hard to rinse, so I just relather for second and third passes from what's left in the beard.The easiest thing to do with a beard is take a hard soap and swirl it liberally over your cheeks and neck. Some will get on your beard, but just leave it there. Rinse the shaved skin when you're done, but not the beard.
On day two, just wet your beard and rub it. You should be able to make enough lather for a second shave.
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