I have only used glycerin once and it was in my first uberlather. Not certain now, but I think it was AOS unscented cream with Tabac soap, a couple drops of glycerin and a splash of T&H 1805 AS. The lather exploded into a thick dense mass which quickly overtook the small pyrex bowl I was mixing it in. When I applied it to my face it was unbelievably thick and creamy and the blade just slid across my face. Without a doubt it was the best lather I have ever had and this is what prompted me to order a large scuttle so that I can use it for making uberlather. Can't wait for my XL-Scuttle to arrive.