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PUL vs. TPU: Delaminating the Differences

by julie on September 26, 2012

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Have you ever wondered what the shiny, tacky-like material that lines many cloth diapers is? Most likely it is either PUL or TPU. I know you are thinking…what the heck do these terms mean? These are acronyms which are short for fancy scientific names. The goal of this post is to give you a better understanding about what the differences are between the two terms and how it applies to you and your cloth diapers.

PUL stands for Polyurethane Laminate. Just like when you laminate a piece of paper or an identification card to protect it, PUL is applied to some cloth diapers to make them waterproof…and of course waterproofing is what allows us to cloth diaper successfully without leaks! TPU stands for Thermoplastic Polyurethane which acts in a similar way as PUL, but with a slightly different manufacturing and application process. Specifically in regards to cloth diapers, PUL and TPU can be found in: 

  • Covers
  • Pocket Diapers
  • All in One’s (AIO)
  • All in Two’s (AI2)
  • All in Three’s (AI3)

What’s the Deal with PUL? 
PUL is a chemical that is laminated onto fabrics such as polyester or cotton forming a flexible waterproof layer. PUL is said to be laminated using solvents in a chemical bonding process

Examples of PUL Diaper Brands
Applecheeks 
Best Bottoms 
BumGenius
Econobum
Flip
Fuzzibunz
Gen-Y Covers 
Happy Heinys
Thirsties
Tots Bots
ZookiesCrafts

Benefits to using cloth diapers with a PUL outer layer:

  • Durable, stands up to many washes
  • Waterproof material to keep the wetness inside the diaper
  • Flexible so it can easily be applied to fabrics
  • Comfortable for the baby

Potential drawbacks to using PUL: 

  • Non-biodegradable (as it is a form of plastic)
  • It is synthetic (man made) and some babies may have a sensitivity to synthetic materials.
  • Not as breathable as other all natural fiber alternatives (wool, fleece)
  • Can delaminate if exposed to extremely hot temperatures 

 What’s the Deal with TPU?
TPU is very similar to PUL. TPU is bonded to cotton or polyester using a heat bonding lamination process which is said to be more environmentally friendly. During the lamination process, solvents are not used, and thus TPU is said to be exposed to fewer harmful chemicals.

Examples of TPU Diaper Brands
Diaper Rite
Gro Via
Kawaii
Oh Katy
Ruparooz

Benefits to using cloth diapers with a TPU outer layer:

  • Said to be more environmentally friendly (biodegradable)
  • Has a softer feel to it
  • More flexible and less stiff than PUL

 Potential drawbacks to using TPU:

  • Said to be less durable (than PUL)
  • More prone to delamination and cracks with higher temperatures
  • It is synthetic (man made) and some babies may have a sensitivity to synthetic materials.
  • Not as breathable as other all natural fiber alternatives (wool, fleece) 

When it comes down to it, both TPU and PUL are synthetic materials. In my research, I did not come across any studies to prove that TPU was better for the environment than PUL. I was surprised at some of the discussions and forums that suggested that PUL and TPU were essentially the same thing, nearly just a marketing scheme to push one product over the other. I guess time will tell as these materials become more widely used in the field of cloth diapers. As for me, I have diapers with both materials and have not noticed any difference in the absorbency of the diaper. I do agree that the diapers laminated with TPU are a little softer ad more flexible than those that have been laminated with PUL. I will continue using both for now as the seem to work well.

What kind of layer are your diapers laminated with?
Do you prefer all natural barriers such as wool or fleece to PUL or TPU?

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