I am just under a year in to pipe smoking. Over that time I have tried many blends and have jarred quite of bit as I am learning what I like best.
Question: when you return to or open some tobacco that has been cellared for a few years, how much time do you then have to smoke that specific jar/tin? Does the benefits of the aging start to dwindle once opened?
Well, it kind of depends. All tobacco has a lifespan. It peaks, and fades.
I've had various experiences with tobaccos cellared for a wide range of times. Tobaccos that have been cellared for 30 years and longer are best enjoyed quickly when opened. They might already be faded, they might have turned into zombie vomit, but if not, those glorious flavors aren't likely to last longer than a day or two. Then, they swoon from the fresh oxygen and croak out.
10 to 20 years the tobaccos I've opened have been fine--assuming that they haven't gone strange-- at least for the few weeks that I'll be consuming them.
Under 10 years the tobacco should be fine to enjoy for as long as you're likely to be enjoying it, even if it's a matter of a couple of months.
There are, naturally, a lot of variables. Latakia tends to
fade, "soften" a little bit by 10 years, and may become almost undetectable after 25 years.
But some of that is affected by the conditions under which the tobacco was stored. That's the great unknown when you're buying vintage tobaccos in the aftermarket. Some of it may have been stored in a stable environment and some may have been cooking away, or freezing, in someone's garage.
The quality of the packaging plays a role. The old cuttertops created a sealed environment, and if stored in optimal conditions, could yield a primo result. But cuttertops haven't been around for almost 50 or more years.
Round tins with screw down lids tend to hold their seal better over the years than square and rectangular metal tins, because the pressure of the seal is more evenly distributed in a circle than in a square or rectangle, and those square and rectangular tins are sealed with a gasket, not a permanent solution. After all, they were only intended to last a few years, not decades.
As for the "benefits" of aging, opening a jar interrupts whatever processes are happening, and after the jar is resealed, the process resumes after a while. But, nobody knows just how the flavors are altered by intermittent opening of the jar, versus, not opening it until you're ready to consume the contents.
Also, aging tobaccos doesn't "improve" them. Tobaccos change, more or less, during aging. Whether that change is an improvement is for the individual smoker to decide.
Recently, I had the unhappy experience of opening some tins and plastic trays of one of my favorite blends, St Bruno. These were all Mac Baren products from 2016. They were all dead as a dodo. The base tobaccos were "OK", but the toppings were gone. This never happened with the Ogden's product.
Shit happens.
