How long can I expect a bar of shaving soap to last? Assuming one shave a day and one pass each time?
A single pass shave? Depending on the soap, you can will it to your eldest child. But seriously, depending on user preferences and the brush you use, you could maybe figure a gram for a three pass shave. More for softer soaps, less for harder. I use mostly moderately soft soaps, (Stirling, Soap Commander, Barrister and Mann) and I average a gram and a quarter to a gram and a half with an average sized (24mm) badger brush. I also have brushes that will devour close to three grams to get a nice three to four passes out of them without having to milk the soap out of it.
Every soap is different. Some are soaps harder (triple milled) than others (glycerin or melt and pour) and thus will last longer. Depends on how hard your water is. Soft water makes lathering easier, meaning you will use less soap and thus will last longer. Brushes are different. A stiffer brush has a tendency to pick up more soap and thus not last as long. Each person uses their brush in different ways than others. Some really twist and grind into a puck, others just kiss the puck with the tips of their brush. The latter can make a puck last longer than the former. Hope that answers your question.
Again, what kind of soap? How hard do you load, do you wash a lot down the drain? Do you use a giant Omega boar, or a twenty ounce travel synthetic? I can get 75 to 100 or even more shaves out of a tub of Stirling.
Ounce per ounce, a hard soap will last longer than a cream. Hard soap has the moisture removed and requires a bit of work hydrating and incorporating air to make lather. Creams arrive already moistened so you are purchasing soap + water in the package. I'm not knocking creams. For a quick lather they are ready to go. Cost per ounce depends on the initial price and length of service on the amount of product used. There's so much variation between ingredients (tallow/lanolin/Vegan/etc), scent (Un, light, strong, and the infinite pallette), plus difference in water quality. It take a real minimalist to shave like our grandfathers - with only one soap.
Along with the shipment of my shaving supplies there was a small package of sampler creams. They were so small I don't see the point in trying to use a brush to get them to lather up.
With creams you don't need any more than an almond-size dollop to whip up enough lather for three pases.
A really easy way to lather cream; is to rub it on you face and start working up a lather right on your face with a damp brush.
Got some "reasonable" lather from the soap I bought. Did the "separate bowl" thing. Still experimenting. Great thing is, I have each and every day to learn!!
People, people, people.......are we forgetting the relative humidity in Steve C's soap storage area? Huge consideration when determining how long a soap will last. Why, once on a trip down the Nile, I watched in horror as a new puck of Williams simply dissolved and vanished in 27 hours, 12 minutes and 7 seconds. I use a calendar and three sets of sports car rallye clocks to time the lives of my soaps. I also divide my tubes of creams in almond sized portions and freeze them on a cookie sheet. This way I'll know the exact day (depending on shipping method) I'll need to order another tube. FYI, a tube of Proraso red yields 204 dollops. Taking that into account and assuming a 2 pass, minor touch up daily shave, we're looking at 102 shaves per tube. Speick cream does not last as long and it may have something to do with the initial starting volume difference between Proraso creams and Speick. I'm currently working on an Excel spreadsheet that will factor in the differential as well as compare any cream with any other cream or soap with "if" statements relating to altitude, air & water quality, actual shave time adjusted for GMT, etc. Once completed, I'll be able to answer the OP's question with undisputed authority.
Please explain the physics and chemistry of how humidity makes soap disappear. I go from CO at 10% humidity to the south often. I notice no difference in soap, and use it at the same rate.
Soaps last longer, but they take a little more work to make lather. I usually load my soaps for at least 30 seconds before beginning to build the lather on my face. With a cream, it either takes a few swishes from the container or a dollop applied directly to my face and then building the lather on my face. So, I can save about 3o seconds of time with a cream as opposed to a soap. I like them both though.
"Creams" were not around when I was a kid, unless you went to the barber. HE had a silver dispensor that warmed and dispensed the cream by the push of a button. I wonder if THOSE "Dispensors" are available for collecting, or if some of you in HERE already collect them?????!!!!!