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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
Best Bottoms 
Gen-Y Covers 
Happy Heinys
Tots Bots

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
Oh Katy

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?


{ 18 comments… read them below or add one }

Monica September 26, 2012 at 1:54 pm

Great article! I’d been wondering what the difference was, so thanks for spelling it out so clearly! I had no idea that I had so many TPU diapers– somehow I assumed they were all PUL.


julie October 16, 2012 at 5:49 am

I used to think the same thing! I can tell a difference now if I look closely!


Suzi Satterfield @ClothAddicts September 29, 2012 at 2:45 pm

I’ve got a mixture of both. I’ve had no issues with delaminating. :-)


julie October 16, 2012 at 5:49 am

That is great! Fingers crossed I haven’t had any delamination issues either!


Kristin March 6, 2013 at 9:49 pm

This is great! I was literally just wondering about this the other day. I’m not a science person and this makes complete sense! Thanks Julie! :)


kelly May 16, 2013 at 12:04 am

I have quite a few fuzzibunz and am thinking of buying some giggle life diapers to add to my stash. I was my fb in HOT water…do you was your tpu diapers in hot? Has it held up?


Erin May 17, 2013 at 1:28 pm

I’ve been reseraching for awhile and this is the best response I’ve heard yet. In my expereince (DS is almost 8 months) the PUL is more waterproof. My BG’s are my overnights, Flips are my go-to during the day. I only use my Kawaiis and other TPU’s as back up. Plus if PUL’s are going to last longer I’ll hang on to those because I need to be able to wash on hot to disinfect and keep the smell down.


julie May 17, 2013 at 2:50 pm

Thanks! I took a lot of time and research to get the information as clear and precise as possible! I love to hear other’s experiences as well! I do belive that the PUL does seem to be more waterproof than the TPU. I use Flips during the day as well. I do however find that the Kawaii GNHW (TPU) are great for overnight because they seem to be a thicker form of TPU. I will be doing a post on that in the next few weeks!


Jenn November 20, 2013 at 1:47 pm

Avoid TPU! The price upfront may be cheaper than PUL diapers but you’ll be sorry in the long run. I have BumGenius pul diapers I bought 5 years ago for my first kid and I’m still sailing through with the second but I only had a dozen. So I purchased over a dozen one size pockets of the cheap Chinese ones under the Sunshine name for about $7 each. They’re TPU and I have 2 that are delaminating after 8 months of use. I know these won’t last for much longer and it’s going to be hard trying to sell these. Just giving people a heads up that TPU is definitely NOT as durable as PUL.


carrie May 29, 2014 at 11:44 am

Hi Jenn,
They’re delaminating but you don’t put them in the dryer or run them through 3-5 cycles or anything?


Glenda December 2, 2013 at 3:14 pm

I am new to loth diapering and wanting to make my own covers does anyone know where I can find TPU to buy?
Thank you?


Jenn December 12, 2013 at 9:41 pm

Try Their shipping prices are high since they’re located in Canada but they’re products are awesome. They have an explanation on their page about the differences between their PUL and other brands of TPU and PUL. hth


cayla February 18, 2014 at 6:14 pm

Was wondering if you have any tips on saving a cover that has a spot starting to delaminate? Only been using it a little over a month. Have used rockin green and just used ecosprout detergents on our diapers. Was wondering if there is a “best” detergent as well?


danielle nino April 27, 2014 at 10:58 pm

Just found out my baby has a sensitivity to polyester. I have to destash all his itti bittis and eco posh fitted. I’m looking to get all natural fibers, mostly wool and cotton. I want to get a few grovias or free time bg. Will the tpu or pul effect him at all?


Mirella Prado May 11, 2014 at 8:26 pm

I came across this website because I have some diaper rite covers that have some spots that leak through the clothes. I wondered if they were made out of tpu and searched for the difference. I was going to go to their site next to see what they were made of but I don’t need to, I found out here. My flip covers are older and are holding up much better, they are in perfect condition. I wash them both in hot water and line dry. So there you have, a difference in the durability between them.


Rebekah May 30, 2014 at 3:31 pm

There has to be a difference. My daughter cannot use PUL (flip over a fitted) without a rash, but TPU (Bumkins) over the same fitted is fine.


Tracey June 18, 2014 at 10:27 pm

Hi Im in the middle of deciding on a waterproof /breathable fabric for the backing of a baby product. My supplier has come back with
100%polyester knit fabric bonded print TPU membrane
usually use for making light jacket , can any one please help me understand if this fabric is ok for me im confused with TPU / PUL as it doesnt need to be high high quality i just need it to be waterproof and breathable


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