Fleece doesn't absorb moisture. It is made from polyester.
There are two different "kinds" of fleece that are used in diaper making. The first kind, Microfleece, is used for inner "wicking" layers (the layer inside a pocket diaper is normally made from Microfleece). Microfleece is thin and and porous enough to allow liquids to pass through it, where the moisture is trapped by a soaker/stuffer pad made of some kind of absorbent (cotton, hemp, etc) material. The Microfleece retains its dry feeling (since it didn't absorb any of the liquid) and therefore "locks moisture away" from baby's skin.
The second kind of fleece is known by a few different names, depending on the manufacturer and where you buy it--Polar fleece and Alpine fleece are a couple of the most common names. This is the "heavy" fleece that is used for
the outsides of pocket diapers or is used for making covers (the stuff they sell at Wal-Mart for making blankets and coats that comes in cute kid patterns). It is not technically "waterproof" (it doesn't totally repel moisture), and occasionally you will have compression wicking with fleece covers (moisture will wick through an area of fleece where the fibers are compressed--for example, by a carseat strap/buckle or tight clothing--but in my experience this only happens when the dipe is **WAY** wet or DS has a heavy wetting moment
) This type of fleece comes in different "weights"--the two most commonly used for diaper covers/pocket diaper outers are 200 weight and 300 weight.
The "best" fleece is made by Malden Mills. They invented fleece, and the brand-name fleeces that outdoor clothing is made from are their products (Polartec and Windpro are two examples). Malden Mills fleece is generally not available in retail fabric stores (like Joann Fabrics), but you can order it online from many diaper-making sites or directly from the company via their website. The "100 weight" is microfleece; as I said before 200 and 300 weight are most common for diaper covers, and you can also use Windpro for a cover. The website for Malden Mills is http://www.maldenmillsstore.com/defa...24116228855211
Now that I've told you all about how great Malden Mills is, all of the pocket diapes and covers that I've made recently for DS are made from microfleece and alpine fleece that I bought at Wal-Mart.
The "alpine" or "polar" fleece that you buy at Wal-Mart or Joann Fabrics seems to be the same thickness as 200 weight Malden Mills fleece; the only difference that I have been able to find is that Malden Mills fleece is coated or treated somehow to resist pilling and fiber loss, so it lasts a little longer.
Fleece is a surprisingly "breatheable" fabric--much more so than PUL! I live in Arizona, and DS stays cool and comfortable during the day and warm and snuggly at night