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In regards to cloth diapers, wool has many uses.
Longies are pants made traditionally from wool sweaters. Wool soakers are knitted or sewn from wool sweaters as well. A Wool Diaper Cover, or
Wool Wrap as I like to call them, is made from either a sweater or wool interlock. When used with cloth diapers, wool makes an excellent 'waterproof' barrier. Wool can absorb up to 30% of it's weight in moisture while also 'repelling' the moisture. It is a property known as hygroscopic property.
When wool items are lanolinized, they have been soaked in a solution of water and lanolin. Lanolin is the natural oil or fat secreted by sheep's skin glands. Lanolin also has water-repellent properties. So when you add lanolin to a wool diaper cover, or longies, you have further ensured no moisture will escape the diaper beneath.
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While wool soakers, covers, or longies can by made using only 80% wool, I prefer to use 100% wool articles. This ensures the wool items I make are of the best functioning quality.
Cloth Diaper users are already contributing greatly to the reduction of trash created in our world. When a family uses a recycled wool item for their child, they are increasing the trash reducing benefits since that wool item was already an unwanted clothing article.