This became obvious to me the other day when a wonderful tea friend (read: tea teacher) and FLT tea source-er brought in an aged mainland Tieguanyin. He lit a candle with an old teapot suspended over it like this (a) and placed a gaiwan lid over the top, like this (b).
My friend waited a few minutes and held the gaiwan lid to his nose. "Stinky!"
He handed it to me. The moisture that had been trapped in the leaves had started to evaporate and re-condense on the apex of the lid. I smelled it. YUCK! It smelled like a stinky navel. So that's what I'm drinking when I drink a long-stale aged oolong. This made the utility of touching up or re-roasting an aging tea very concrete to me. I don't want that stink in my tea! Gross!!
On top of removing stink, my own touching up experiment was more vibrant, clear and strong than when I've drunk it stale. I tried the other day on an aged Miao-li area oolong in the shop, and even the energy of the tea hit me hard and immediately, whereas that tea has always felt sleepy to me. The only problem with amateur roasting-touchups is the tea tends to get a drying feeling in the mouth that it wouldn't have otherwise. And the way I understand it, most of the time if you set it to rest after the touch-up it will go back to the way it was. "Locking in" a tea when touching it up, or roasting for any reason, is necessary for aging. Roasting is no easy skill, and locking in a tea so it remains relatively consistent takes direct experience, oral teaching, and a 'warehouse full of mistakes'. I hope one day I have enough tea to experiment like that, and eventually learn to lock in teas with a good roast. For now I'm just happy I could refresh a tea at all! Very rewarding session.
This is the aged Miaoli Oolong that I was playing with.
Disclaimer: Here's a link to the Miaoli oolong I was experimenting with. I just want people to know I DO work for the company (FLT) selling that tea. I only work there part time and don't profit directly from any sales, but I am involved with and love the company. That being said, I work for her because I really respect what she's doing and love the tea she sells.