I used to use cedar or pine bedding for my gerbils, mice, hamsters and rats until a veterinarian told me that the dust from that type of bedding can cause allergies, upper respiratory problems and the phenols found in some wood shavings, especially pine can cause respiratory distress.
Fleece cuts down on the dust, is soft for rats to walk on and lay on and it saves you money because it's reusable. It's also absorbent and can easily be changed out for clean fleece when it starts to smell, which depending on the number of rats you have would be once a week. Fleece also comes in a variety of colors and patterns that make the cage look nice and you can pick patterns to match the different seasons and holidays.
I also use cotton baby blankets for the shelves and different smaller levels in my rats cages and use binder clips to fasten the baby blankets to the shelves. I also use the cotton baby blankets inside the rat houses and beds so they have something to burrow under and into and snuggle with when they are sleeping.
Care and Maintenance of Fleece
I buy fleece throws that I find in most stores for around $3 a piece so they are cheap enough to throw away if my rats chew holes in them, which they do quite often. I use scent free liquid laundry detergent when washing my fleece blankets because strong smells can cause rats to sneeze and create excess porphyrin and they can also be allergic to some of the chemicals used to make laundry detergent smell good. I started using scent free detergent after my own rats showed signs of allergies to the strong odors in the laundry detergent I was using.
If the fleece still has a urine smell after washing you can use 1 cup of distilled white vinegar in with the detergent and that will cut down the urine smell if detergent and washing alone doesn't work.
People in the rat community are very knowledgeable and when I asked how to get the urine smell out of fleece. Sandra Sneed from Dunedin, Florida said, "Vinegar is so acidic that it destroys organic molecules, including the ones responsible for pee smell (in everything! It's GREAT). Strong enough to react with lots of them without losing strength, but weak enough that it doesn't damage fabric, carpet and such."
My rats, especially my younger rats will chew holes in the fleece quite often and if this happens to you, I don't recommend sewing the hole up because they will probably chew that as well and can choke on the thread. Just replace the fleece or cut it to fit the smaller shelves and levels.