The dewbie will soak up, on average, about 2 grams of water over two minutes, but absorbs the majority of that within the first 30 to 60 seconds.
That will be determined by quantity, how dry the herb is, what you are storing it in, and how you like your buds. A dewbie will refresh a couple of grams in 10 to 20 minutes using a small jar with a good lid, but a really dried quarter ounce can take an hour or two. In the case of an ounce, rehydration may take 8 hours or more (typically turning 28 grams of dried out weed in to 29.5 grams of fluffy weed overnight).
In the case above whereby you've re-hydrated an ounce, you can leave the "waning" dewbie in with the herb while smoking the contents of the jar. In this way, you are maintaining hydration despite many openings of the container. THAT SAID, if you were to leave a well-soaked dewbie in a sealed container with a relatively small amount of cannabis, you risk over-hydrating your stash.
Spread your bud(s) out on a piece of paper to let dry (if crazy soaked), or simply leave the container open until sufficiently air-dried.
Yes, a completely dry dewbie will help to draw moisture out of newly-cut flowers and the like. It won't, however, fix weed that went thru the washing machine...To be absolutely certain that your dewbie is completely dry, place it in a warm or hot oven for an hour or two.
The dewbie is handmade in Calgary, using Canadian materials. It was created by a (retired?) chef who saw a need after Canada’s legalization of cannabis. It is infinitely reusable, and should last 1000+ years (when treated correctly). However, some people infuse their cannabis by adding essential oils to their dewbie. We think this is a great idea, but please be aware that, over time, the pores within your dewbie will become clogged and you may need to replace it if this happens.