You just got brand new cloth diapers. Now what? Do you need to pre-wash them before use? How many times? Here's what you need to know.
Synthetic Fabric Diapers
Yes you need to pre-wash them once. If you have purchased covers, pocket style, all in two or all in one type diapers made with synthetic fabrics like microfleece, microfiber, micro-suede or athletic wicking jersey, you need only wash once with detergent and dry them before use. The fabrics themselves do not need any prepping to be absorbent for use on baby, however, shipping and packaging dust etc. should be removed before they go on the bum.
Natural Fabric Diapers
If on the other hand you have purchased cloth diapers that are made in any part with natural fabrics (bamboo, bamboo fleece, bamboo velour, cotton, organic cotton, or hemp) then some pre-washing is necessary. The more unprocessed the fabric is, the more pre-washing it will require. For example, for bamboo, bamboo fleece and cotton, the manufacturer might recommend 3-5 pre-washes before use. (You can get a way with 1 pre-wash (keeping in mind that the diaper will get more absorbent over time and subsequent washes. So if you get a bit of a leak, never fear, it will resolve with more washes).
However, if you have un-bleached hemp, organic cotton or organic bamboo - which still contain lots of natural oils when brand new - expect to do 3-5 pre-washes before they will be absorbent enough to begin using (and they will also gain absorbency over time until about the 10th wash). Expect some shrinkage up to 25% on these materials after washing as the pre-washes will remove the naturally occurring oils as well as quilt and fluff up the fabric to be nice and soft and fluffy.
Covers made of PUL (polyurethane laminate) or TPU (thermoplastic polyurethane) do not need to be pre-washed, but similar to the synthetic fabrics discussed above, should be given one pre-wash to ensure they are clean before use on baby.
Wool needs to be lanolised before use as lanolin is what makes is water resistant when used as a diaper cover. So, if your wool cover has already been lanolised, then go ahead and use it on baby straight away. If not, then you'll need to wash it with special wool wash, lanolise and dry it before use.
**NOTE: Pre-washing means washing with detergent. Each wash with detergent will help remove natural oils in the fabric that are not chemically stripped away during typical fabric manufacturing. If the oils were left in the material when you went to use them on baby, the naturally occurring oils would cause the fabric to repel and not absorb properly.