I have two Hungarian oak barrels and the more I use them the longer I keep the mead in them. I also use cubes in carboys in the secondary and I'd guess most of them are oaked for a month or so. Rather than concentrate on the time I adjust the amount which varies depending upon the variety.
Oak is a double edged sword. It can really add great qualities to a mead, but one of the surest ways to ruin a good mead is to over-do it with oak. It doesn't take that much (at least for me) to drown out the lighter aromas and flavors especially with some delicate fruits. I find that 1 gram per liter (less than an ounce for a 5 gallon batch) is often enough, and the "you can always add more later" rule definitely applies here.
I find light and medium toast oak works better in most mead. I find the heavy toast stuff works only in some cases such as big red wines; heavy berry meads; sweet orange meads; and heavy, sack-strength, dark-honey meads. It might also work with some Braggots and with some chocolate batches. YMMV.
Medsen
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