i've read where it is suggested that soaps have limited life span once opened. does this apply to arko stick, pucks in a tin, fancy triple milled french soap, poraso in a tube, croaps? do soaps spoil? what happens? what about unopened soaps? what about those with massive soap collections? or is this a manufacturer ploy to sell more product?
I've been at this for about 4 years now. I've only finished one tub of TOBS Sandalwood cream and then bought another. I now have opened about 50 soaps and creams, some of them samples and others full tubs or tubes. I have yet to see any of them "go bad." The only thing I have noticed is with the creams in tubes like Proraso and Musgo Real, the cream near the opening of the tube tends to get hard and clog the opening a bit if not used regularly. I then have to squeeze the hard stuff out to get to the soft good cream further down. It's not a lot but that's about all I've noticed. None of my tubs of anything have gone bad, soap or cream.
It's not unheard of for vintage tallow-based soaps to occasionally go rancid which is immediately obvious via the sniff test. But, otherwise, you have nothing to worry about. Doubly so if it's not a tallow base. With modern preservatives, I doubt spoiling is ever an issue unless something was made incorrectly. The expiry date you see on some products is due to governmental regulation and not a statement of actual viability. It is massively more likely that you will finish up a product -- even if you have lots of products in rotation -- before something goes bad. Edit: cream products will sometimes separate or dry out. But, with a good stir or hydration, as the case may need, they are usually good to go. Cream products may also appear to be spoiled or broken down if they get frozen. Sometimes they can be rescued, sometimes not if freezing is the culprit.
I have several vintage cakes of colgate and williams...also some tubes of palmolive..the older stuff. I use them all..never had a soap go rancid on me yet.
Oldest two soaps I own - a stick of Vintage Williams made no later that the early 1960's & a puck of Colgate with a printed box price of 15ยข. Both were bone dry when I found them in the wild. That's good because water allows for bacterial growth. I enjoy lathers from either. The only performance reduction? Scent seems to have faded. Triple milled soaps have so little moisture they last well if properly stored. Creams tend to contain preservatives because of the added moisture. Only one puck of soap I've ever tossed - Marvy. It was fresh off the shelf of a retail store, but may have been setting there for a while. Smelled like rancid meat which makes sense if the tallow turned. Or maybe they make it in that scent.
I had a Cella tub that smelled rancid right off the bat. When I checked with the vendor, it had apparently been on the shelf about 2 years. I've never seen tripple-milled soap go bad, just lose some of its scent.
I remember watching NickShaves do a bathroom tour video a few years ago - and he showed viewers his soap drying shelf on which he had a couple of soaps inverted over a towel to let them drain and dry. I was like "too much work. I'm not doing that". But he was a soap-soaker, if I remember correctly - he'd put water on the puck and let it soften before he loaded. And when you have as many products as he had (or I have now, haha) then it's easy to have a tub of soap that sits for weeks if not months in a row without ever being used or allowed to breathe/dry out. So I can now understand why he did it. Then again, how many people don't do that and put their soaps away wet or damp and never run into mold? Probably most, I'd think otherwise we'd see horror stories all the time instead of extremely rare mentions. I scrape and bowl lather most my soaps. About half of the 60 or so products I have on hand are sample jars, so I kind of got into the habit. But if soaps do go bad... I'll be in trouble!
I've used tallow based soaps for a very long time and only had two go rancid. Both were likely my fault as I closed their containers before putting them away for several months while still wet. Daily use shouldn't be a problem. If you think you'll be stowing it for a while, just let it dry out over night.
Cella is the only soap I have had that went bad. Stinky stinky. All others, for example, Proraso, MWF, Tabac, TOBS, Jabonman have been good even if a number of years old.