I've only raised two batches of chicks, so I'm by no means an expert. However, I found a method of alleviating pastey butt that has worked both times that I thought I should share. It's essentially a chick spa! I started with the usual washcloth wiping, etc that all seemed to cause discomfort to the chicks. With this, they don't seem discontent at all (actually had one fall asleep during it). They put up more of a fuss when I'm moving them than when I'm actually cleaning them. For this, I use a disposable, shallow dish that is about 3 inches high, like a gladware container. The second necessity is an old toothbrush (obviously all things are destined for the trash after the spa). I fill the dish with water that is just warmer than lukewarm and don't add anything else to it. I take the chick and cradle it under the belly with my fingers and set it in the water. If the water is the right temp, they just settle down and let you hold them there. I try to use just enough water that their feet touch the bottom and that their butt is just under the water, but I cradle them the whole time. I hold them there for about 2 minutes or so and then start gently massaging the poo off their butt under the water. As I get to crustier areas, I just let them soak in the water longer and then start again with the toothbrush. The whole process takes about 5 minutes, and they don't mind it at all. Plus, I can get all the poo off without making their butt sore or pulling out their feathers. Afterwards, I dab their butt a little with a papertowel to get the excess water off and then put them back under the heat lamp. I have 4 happy little ones that just finished their spa treatment, are shaking their little tail fluff and are falling asleep as I write this.