I had quite a few scraps of yarn from various projects, so my balls are uncoordinated:
Mine went through two wash loads (one hot and one cold), and then through the dryer. I like the way they turned out, and I'm using them this morning as I do laundry. So far, so good! :) I read that you can use from 3-6 balls in the dryer, so I'm thinking of making a few more.
If you're unfamiliar with dryer balls, their purpose is thus:
:::to separate the laundry as it tumbles to help it dry faster, preventing the laundry from bunching up
:::to prevent static so laundry softener is not necessary and
:::if they are wool, to absorb some of the moisture from the laundry, speeding up the drying time
Project notes: we had a wool sweater which was felted, and we started our balls with a folded strip of the sweater, so we wouldn't need quite so much yarn. Then we just wrapped and wrapped and wrapped...after that we stuck the balls in nylon knee highs, separating them from one another by either a knot or tying it off with yarn. The nylons accomplish two things: they help the balls hold their shape through the wash and they prevent lint from clogging your drains. Also, it is important to note that 100% wool yarn that has not been treated for washing is necessary (the yarn will be labeled "washable" or "superwash" if it has been treated).
Unrelated: here you can see a glimpse of my flower bed. Everything but the petunias are perennials. I'm excited to see the Asiatic lilies bloom. I have three and this year two of them have reproduced. I'm not sure when to split them, but I assume it would be after they bloom. I'll have to look into that.