Tea Towel Test - Failed PUL

8 CommentsSaturday, 26 July 2014

The Nappy Lady Tea Towel Test

We often get people worried that their PUL wraps (waterproof covers) have failed when they get leaking nappies.  It is always a possibility but isn't usually the first thing we consider if we know you're using good quality wraps.

PUL covers are fairly durable is you have good quality ones to start with and have cared for them well.   The waterproof cover is ALWAYS the most important part of a nappy system and a great wrap can make even a very basic nappy work reliably. This is the reason we always recommend you use the best quality wraps you can get (Motherease are ALWAYS our first choice) and if you need to economise on the nappy system do this with the nappy part not the wrap!

There are different grades/quality of PUL as with everything in life, the saying you get what you pay for is normally right when it comes to PUL longevity.

PUL can degrade and fail if washed with harsh chemicals, washed too hot, tumble dried too hot, dried on a radiator or even just physically pierced. If the PUL fails there will be a way for urine or any liquid to get through the waterproof layer and lead to leaks.

If you are worried that your PUL has failed we like you to perform the "tea towel" test rather than relying on leaks while baby is wearing it.  When baby is wearing the nappy/wrap there are too many variables to consider such as level of absorbency, speed of urination, fit, length of time the nappy is left on. The "tea towel" test removes these and just tests if the PUL has been compromised.


  • 2 Clean Dry Tea Towels or Muslins. Must be flat absorbent cloth.
  • Suspected Failed Wraps/Covers
  • A clean dry surface which won't be affected by water eg a kitchen counter


  • Firstly get the wrap which you are concerned about and make sure it is clean and dry.
  • Get a clean dry tea towel and fold the tea towel into a rectangle that will easily sit inside the wrap away from the edges and binding of the wrap.
  • Make the tea towel wet but not so that it is dripping.  If you wet it too much so it's dripping it won't be a fair test as the water could just drip or roll off of the wrap/edges.
  • Place the damp folded tea towel inside the wrap you are testing. Remember is MUST be away from the edges and NOT dripping. 
  • Lay the second clean dry tea towel onto a flat surface that won't be affected if it gets wet eg a kitchen counter
  • Lay the wrap with the tea towel inside OPEN on top of this second tea towel.
  • Leave for 30mins
  • After 30mins if the clean dry tea towel the wrap is laying on is damp at all then your PUL has failed as water is getting through the PUL membrane. The wrap can't be saved so should be removed from your nappy system.  If the tea towel is still dry your PUL is intact and PUL failure ISN'T the reason for your leaks.

    If you have failed PUL wraps nappy libraries will gladly take them off your to make into nappy keyrings for fundraising.  The address to send you failed PUL wraps is below, please include a note so that they know they are not to be hired out but to be recycled WHNAS, 3 Bellars Lane, Malvern, WR14 2DH


Friday, 10 November 2017  |  21:39

Thanks so much for this informative article. My tots bots AIO nappies have all recently started to leak around the edges and I thought I must have ruined the PUL layer by tumble drying them on the "wool" setting for 40min ( which I had assumed was the equivalent of "low heat")
You mention to do this test by placing the wet tea towel AWAY from the edges and I wondered why this was? If I do the test as described above, and there is no leakage, what might be th reason for the nappies to be leak around the edges instead?

Saturday, 7 April 2018  |  12:02

It's just to keep it away from the edges so it doesn't roll/dribble off the side of the nappy to the outside making you think the PUL is leaking through and it's not. It's just fluid escaping over the top/sides if that makes sense.

Vicki Perry
Saturday, 2 March 2019  |  15:00

What about if the nappy leaks if you press hard on it with a wet towel underneath? Would hey all leak under those circumstances? Thanks.

Sunday, 7 July 2019  |  10:10

PUL is water resistant not waterproof so it's likely they would all leak under this scenario

Rebekah Griffiths
Monday, 10 June 2019  |  10:58

How do you test if the PUL is compromised in a pocket nappy? Just wet the inside of the nappy and leave for 30 mins?

Monday, 8 July 2019  |  20:49

Our method is suitable for pocket nappies as well

Mohamed Abdulla
Sunday, 30 May 2021  |  16:37

Thanks for this excellent article.
I have sewed a PUL pocket diaper. But I feels the water is coming out from the thigh elastic region. It is not leaking. But it spreads the water through out outer PUL via the thigh elastic regions. We have seperately checked the PUL, fleece, and Insert pad for leakage. Raw material wise quality is very good individually. But when it comes to final product, cloth diaper. We feels the water spread through PUL via the elastic and alarm the mam by showing wetness in the outer layer quickly. But baby contact regions like you inner fleece are getting dried immediately. So, no problem with baby. But with less than 60 ml, it alarms the mam by spreading wetness in Outer PUL through elastic.
We are using 19 point ball point needle and spun polyester thread.
Already we have sewed 350 diapers, we are finding this issue now.
We are struggling with this issue a lot.
Kindly help us in this situation.

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