Purchase two packages of Rit Fabric Dye (available at Walmart & most craft stores for around $2.20 a box) You want to get a box of Denim (or Navy) and a box of Black.
Get a large bucket or rubbermaid bin and fill with about three gallons of very hot water (enough to cover whatever you are dyeing.) Add a cup a salt and empty the two Rit packages in the bin. Stir everything up and add a pair of jeans to the mixture. Let sit for 25-30 minutes a pair, stirring every couple minutes to make sure every part is saturated.
Hang to dry, then turn inside out and wash and dry. We were able to do 3-4 pairs for every batch. You can do more, but the dye may not be as dark. (You can always buy two boxes of each color and do a double batch!)
BEFORE & AFTER:
Have you every dyed your jeans before? If so, do you have any tips or tricks? Please share below!