Best way to wash (blanket, cloth, clothes) for bedding for pet RATS?

I will soon be buying two little ratties and I know everything to take the absolute best care for them except I want to know things like what detergent I should use, or whatever to make sure that it doesn't harm them when I clean the bedding, I would like to use fleece or felt. Which should I use too, fleece or felt? Any washing way that's great and money efficient?