I don't think it will come as a surprise that for a traditional shave you use either soap, cream or foam.

If it is to be kept completely traditional, foam on a can is out of the question, and you are left with the choice of soap or cream.

A traditional shaving soap was based on tallow and thus hard as a bar of hand soap. You could use a hand soap for shaving, but the shave wouldn't be comfortable. The reason being that there is a difference between hand- and shaving soap and the difference lies in the foam they create (known as lather when shaving). At first it might seem that a hand soap creates a lot of foam, but the foam will disappear quite quickly, and would you are looking for when shaving is a foam that stays for as long as possible as it protects the skin during shaving.

Today you can't find many soaps where tallow is the main ingredient, most manufacturers has exchanged the tallow with glycerin which is cheaper to use and easier to handle during the manufacturing process - even though I think the first reason is the most important.

My experience so far is, that if you are using a DE-razor, it doesn't matter if you are using soap or cream, but if you are using a straight razor a hard soap seems to work better. The lather from a hard soap makes a better cushion for the blade than the lather from a cream - strangely enough.

Soap

(discarded as a shaving soap, the lather is to poor)

(in bowl from Tiger)