Heat 2 gal. water to 160 and dissolve 10 pounds honey into it. Pasteurize for 15 minutes.
Add 2 more gallons room temperature water to pail.
Pitch yeast into must, and aerate.
Seal and airlock for one month.

After a month, rack the mead into another plastic pail onto the blackberries in a fine mesh bag. Add 25-50 oz of raspberries if you like. Let sit for one more month, then rack to a carboy, adding another 1.5 pounds of honey dissolved in water. In another month, rack again, topping off if necessary.

This mead ferments out dry, with a good blackberry nose, and a nice body. Complex flavors, but clean.