We have created this page because we get so many emails asking for our opinions on these things. Take it all with a grain of salt, for these are opinions, not scientific facts.
A 10% polyester base with cotton over it is very common in many diapering products, and surprisingly even in many WAHM hemp products. Most of our diaper are 100% cotton diapers, because we have found cotton to be the least allergenic and the easiest to wash.
As you shop and compare our products with other sites, know what the diapers are made of to make an informed choice. Can't find the material content of a particular manufactured (non-WAHM) diaper? Ask the seller. We won't list the popular brand names here, but there are quite a few. Hint #1: price - in general, polyester-based diapers are less expensive than pure cotton diapers. Hint #2: if it just says "cotton diaper" and doesn't say 100% cotton, it probably is not 100% cotton.
Our 100% polyester products
Stay Dry Liners, Stay Dry Doublers and Night Stay Dry Doublers are in the 100% polyester category. Using polyester next to baby's bottom is rather new. Polyester fleece does work to keep baby dry. Does the dry-feel matter? What's your opinion?
It's up to you. Disposable diaper makers say that "feeling dry" matters, but I'm not convinced.
Polyester is a man-made synthetic. It came in to fashion for diapering 1998. No long-term studies have been done as to it's safety. Is it safe? I don't know. Until a long-term study has been done, I can't know. Some people are "allergic" to polyester. Some people are "allergic" to disposable diapers. I have not yet heard of someone being allergic to 100% cotton. Individuals with chemical sensitivities are often intolerant of polyester.
Personally, I would certainly choose to have polyester next to my baby's bottom over a chemical-filled disposable any day. But really I choose 100% cotton all the time and avoid polyester next to baby. I generally avoid polyester in our clothing and bedding also. And microfiber is just ewww! I can't stand it. Read more on our Diaper Definitions page. Even over the "chlorine free" disposables, which still have the chemical sodium polyacrylate in them, which has documented risks associated with it. Sodium polyacryalte or polyester? It's up to you. I choose neither. Pure cotton is my personal first choice.
Remember everything has it's tradeoffs. The disadvantage I've found is that polyester is a bit "slippery" when runny poop hits it, and once in a great while I've had a minor, runny poop escape with polyester, which is rare with traditional cotton diapering systems. The containment success for runny, explosive poops for polyester inner pocket style diaper about equal to that of disposables. Remember, disposables don't contain EVERY explosive runny poop, either, and you might be surprised by how many people using disposable diapers buy cloth diaper covers to put over their disposables - that's true! Anyhow, this makes sense. Here's why: 2 piece systems (diaper plus cover systems) have 2 levels of containment: 1=diaper, 2=cover. But all-in-ones only have one leg elastic for 1 stage of containment. Cotton actually absorbs quickly and that includes absorbing the runniness of poop from a breastfed baby that needs absorbing. A cotton diaper with a cover over it is very effective.