This may be a stupid question and I could very well be missing something somewhere but...here goes
I recently priced a roll of 90% silver dimes at $48.50, that makes each dime worth 97¢.
Now, let's say that the dollar collapses and I need to spend some of this junk silver to buy whatever. The seller of X item, not being versed in PM's still only sees a dime, whereas I know its worth to be 97¢. How do I keep from losing 87¢ on the transaction?
If he wants to sell you an egg for one of the 'new dimes' then we wouldn't have a currency collapse- he would still be accepting the federal reserve notes essentially. Once the currency collapses no one will be interested in taking any of the new money for purchase of anything. So you won't be able to buy an egg with that new dime. Instead some other currency would have to replace the current currency we use. Now that could be silver or gold, or perhaps it would be alcohol and cigarettes or bushels of grain or gallons of gas. I believe that historically whenever currencies have collapsed people find substitutes to use for exchange. Most recently these substitutes have been the US dollar - but PM's would probably fill the void in a currency collapse.
So you show him the silver dime, tell him you want a dozen eggs, and he says it's only enough to buy one egg, then just give him a new dime or shop someplace else.
When the currency collapsed in Ecuador about 9 years ago people who could not read had no problem using substitute currencies- gold/silver and US dollars - everyone knew very quickly what the new currency was worth- it really would be very important for people to learn fast (or they'd get burned).
I've been to Ecuador twice and the people are often extremely nice, happy and pleasant- but I don't think they are more savvy financially than Americans in general and they certainly don't have the resources to learn as fast as we do- so I think the American public would learn almost instantly.
In a currency collpase there'd be a run on banks, retail stores, grocery stores, gas stations, - everyone would try to stock up, store owners would stop taking plastic, stop taking federal reserve notes, and start taking something else, or they'd suddenly find their shelves bare, have a stack of FRN's that neither their employees nor their suppliers want- these stores would then be out of business.
In short I think it's a good idea to be diversified even in precious metals, and even diversified within the silver that you buy etc- otherwise you may find that you are stuck buying 40 dozen eggs from me if all you have is that 1 ounce of silver and I don't have change (assuming the price of silver would also jump markedly in a currency collapse).