Wednesday, November 19, 2014

What is PUL and are you Correctly Caring for it?

PUL stands for 'polyurethane laminated' and it’s a type of waterproofing fabric used in cloth diapers and wet bags.  I have a post where I show how you can purchase PUL at a fabric store and use it to make your own wet bag (aff link)!  PUL has properties like elastic and rubber, which combine to give fabric a flexibility and waterproofing. If there is a problem with the PUL layer in diapers or wet bags, it can jeopardize waterproofing.  I wanted to mention a little more about PUL: specifically, I'll address what it should and shouldn't look like and how to care for it.

We learned a lot about PUL problems in 2010 when we discovered we had a bad batch of pocket diapers.  I began noticing the PUL layer bubbling up across the back of many of our diaper covers.  It looked like a plastic layer separating from the colored shell of the diaper.  Since the PUL had separated, it really increased the risk of it catching on something and tearing, or possibly even cracking.  We had only been using the diapers for a few months, and I had been line drying the diaper shells 90% of the time.

I immediately went onto the company website and checked the warranty of the diapers.  PUL problems were covered for 1 year.  We were able to return the diapers to the company and they sent replacement diapers plus some freebies to cover our cost of shipping.  We discovered that this company had a period of major PUL problems resulting from bad craftsmanship at their plant.

Cloth diaper manufacturers are not alone in experiencing PUL problems--even wet bags can become "delaminated" (separation of PUL and fabric) and rip. In the image shown, a delaminated wetbag was used for months before it finally tore.  We continue to use the wet bag despite the damage (which is near the top of the bag). Well-made PUL should last for a very long time without experiencing these issues.  Most of our cloth diapers have lasted over four years without experiencing any delamination. 

PUL comes in many colors and textures, so don't be worried if the waterproofing on your diapers seems to look different than other images of PUL.  For example, PUL may have large, honeycomb-style texture or almost no texture.
You can help keep the PUL layers of your diapers and wetbags looking nice by line drying your diapers whenever possible.  Think about T-shirts with plastic embellishments on them--if you put them into a hot drier, the design tends to crack (unless you turn T-shirts inside out).  This is because even on low, a dryer still gets pretty hot for plastic material.  I would also recommend not using homemade detergents on your cloth diapers and wetbags because acidity levels or the chemical composition could be too harsh for the delicate PUL layer.  Do not use vinegar or baking soda in your wash.  Using vinegar once or twice might be fine, but repeated use of vinegar can damage PUL and elastic.

Have you checked your cloth diaper or wetbag PUL to see what it looks like?

Kelly's Closet link is an affiliate link.


  1. It really depends on the PUL. Some are manufactured to withstand high heat, since it was originally designed to be used in the medical industry and stand up to autoclaving. Those would be fine to toss in the dryer. However, there is some that is made to be used for things like diapers, and to make it more inexpensive, it probably isn't made as durable so can't withstand the very high heat. The problem is that it is hard to know which kind was used in the diapers you have. I would assume the cheaper brands probably use the less durable stuff.

    1. Very good point! I believe that the variety intended to be autoclaved is much thicker, so I would be surprised to see it used for cloth diapers because it wouldn't have the needed flexibility. I have noticed some brands have more issues than others. The above wet bag that delaminated was actually a replacement for another wetbag of the same brand--also delaminated and returned to the company. You can get by with these delaminated fabrics, but you have to be very careful. I line dry covers when possible, or dry on low heat (per manufacturer's recommendations).

  2. Most diaper makers today use 1 mm PUL fabric as it is more supple. Some makers used to use 2 mm PUL fabric. It was a bit more durable but not as supple.

    In addition, the big maker of PUL fabric that diaper makers used went under a few years ago (fabrite). They had hands down the best formula for durable PUL and their stuff lasted 4+ years. Unfortunately, when they went under, so did their formula. Other companies have tried to fill in, but you are lucky to get 2 years. That is why some makers diapers made years ago have lasted so much longer than recent batches.

  3. I am a little bothered by some of the statements made in this article. Not all homemade detergents are acidic. Some are very neutral to slightly basic. Also many commercial varieties also can be very acidic. For example I make liquid detergent from soap nuts and my final product is close to Ph balanced if a bit basic.

    Also not all PUL is created equal. Quality can vary batch to batch and diaper to diaper even in the same diaper company. I've had 3 delaminate from the same company after the 2nd or 3rd wash, and the other 7 I bought at the same time were fine. Sometimes for various reasons the PUL is not as resistant. It still can very greatly.

    1. Nicki, thanks for your thoughts. I'm happy to hear you have pH tested your detergent and had success with it in your type of water. Of course, homemade detergents can be completely fine, but if people haven't done the research to figure out a good recipe then there can be risks to "experimenting" with their diapers. We have personally tested soap nuts and had success with them:

  4. I really appreciated this article, Nissa. I've always been a bit uncertain about the look of PUL when it has issues because there are so many different styles. The photo illustration is very helpful. I will say that I've only had 1 diaper and 1 wet bag delaminate - same brand and a highly respected one. I regularly dry my diapers in the dryer and many have lasted for 5 years.

    I actually think you make it very clear that not all PUL is equal, even from the same company. I guess this is why it's helpful to pay attention to warranties. Thanks for the informative article.