Why use wool covers - an experiment

I started using wool in a desperate attempt to figure out something for night time diapering.. I never knew that I would fall so in love with it =)

 
But why?! why is wool so effective for night time diapering, aside from some information for you I also did an EXPERIMENT! <<insert mad scientist laugh here>> (followed by a girlish giggle) hehe. along with my many other interests I do love a little science  

 
Why does wool work well at night?Night time diapering can be a challenge because with the length of time the diaper is being worn can cause it to get extremely wet, this can cause problems like discomfort and rash

Wool is a great choice because:

- it is water resistant AND absorbent, the outer exterior is scaly called the cuticle and is covered by an epicuticle that is coated in lanolin making it water resistant. The inner part of the fiber called the cortex is water loving and absorb up to 1/3 of it's weight before feeling damp.. so if you're cover is approximately 4oz, it can absorb around 40mL alone before even feeling damp.

- it is breathable and pulls moisture away from the body through the cover and to the outside to slowly evaporate

- it is antibacterial to help avoid rash and stink

- it is flame retardant



so onto the experiment:

Experiment on the power of wool

I set up the experiment: a wool cover with 1 unbleached indian cotton prefold for absorption (at night I usually use 2 however)

I hung it over a glass container with a dowel rod so that I would be able to see if the cover leaked or dripped out

I poured in 40 oz (125mL) of water directly to the middle into the prefold in the wool cover

 

I checked this approximately every 10 minutes for any changes and observed no drips or leaking

I applied pressure from the inside (to simulate the weight of a baby on the diaper) to check for a 'pressure wicking' and even with pressure applied to inside and outside simultaneously I felt no wetness on the outside even though at 30 minutes after 'wetting' the diaper' the prefold was wet the entire length front to back from absorption

After and hour of checking I decided to add another 4oz. (125mL) to the diaper making a total of 8oz (250mL)

I again observed no drips or leaking

 

I then again applied pressure from the inside (to simulate the weight of a baby on the diaper) to check for a 'pressure wicking' and with pressure applied to inside and outside simultaneously, this time I felt some wetness on the outside. At this point the prefold is literally over saturated with wetness.

So what does all of this technical business mean?

I gathered some information on the actual volume of urine output for a child to see how much a child will likely urinate during the night.

Newborn and infant up to 1 year: normal is 2 ml/kg/hour

Toddler: 1.5 ml/kg/hour

Using these rates for a 1 year old up to a 20lb (9kg) and a toddler up to a 35lb (16kg), I found an average of 25 mL per hour

So as a 'heavy wetter' a child could potentially urinate up to 300mL overnight, if sleeping for 12 hours.

The experiment tested up to 250 mL at which point there was some pressure wicking (potentially wet clothes/sheets here)

Wool can hold back the wetness and then absorb up to 1/3 of it's weight before feeling damp.. so if you're cover is approximately 4 oz (which is about what mine weigh) it can absorb around 40mL alone before even feeling damp.

Since we are only using a single prefold (to simulate an entire night of sleep) I think that after 250 mL of wetness if all we are getting is some pressure wicking, that the result is pretty good. I use 2 prefolds at night for more absorption.

I would like to mention, the pressure wicking would/should NOT happen if there were adequate absorption under the wool cover and if the cover is properly lanolized.

When the prefold, fitted etc (absorbent part) becomes so wet that it cannot hold anymore wetness the wool will begin to absorb the wetness and the wool will start to feel wet when it starts to become saturated. The wetness you feel then on the outside is the wool pulling the wetness away from the body and letting it evaporate on the outside of the cover.

All of this happens because of the structural make up of the wool fiber itself. the outer exterior is scaly called the cuticle and that is covered by an epicuticle that is coated in lanolin making it water resistant. The inner part of the fiber called the cortex is water loving and the part that does the absorption.

I hope that I didn't lose you by this point and that you enjoyed this =)
I hope that this helps show the awesome power of wool or at least explains a little more about how it works