PUL or TPU: Which is Better For Cloth Diapers?

If you’re diving into the cloth diapering world, you may be wondering whether a TPU or PUL cover is best. You might also be wondering what those terms even mean. If your biggest reasons for cloth diapering are to provide more natural materials for your baby’s skin or to be more environmentally friendly, you’re going to want to know this.

It’s important to understand the various different fabrics used in cloth diapers. Why? Because different fabrics and materials contain different benefits, and we all use cloth diapers for slightly different reasons. For example, if you’re a crunchy mom looking for more natural materials to diaper your child’s sensitive skin, PUL/TPU likely wouldn’t be your first pick. 

In this article, we’re going to cover the key differences between PUL and TPU fabrics in diaper covers, their pros, and cons, as well as offer effective alternatives for all-natural mamas.

TPU (Thermoplastic Polyurethane) and PUL (Polyurethane Laminate) are incredible choices to be used for the outer layer of diapers or as the fabric for diaper covers. They keep the wetness in while allowing some airflow to reach the baby’s skin. PUL/TPU material is very durable, even under the thorough washing conditions needed with washing cloth diapers.

However, did you know that TPU is actually still PUL? What makes TPU different is simply how and what they laminate the fabric with. 

NEW TO CLOTH DIAPERS? See our post on cloth diapering for beginners to set the foundation

What is PUL fabric? 

PUL (polyurethane laminate) is a fabric (most often polyester) that has been laminated with a plastic polyurethane film. 

The laminate can be bonded to the fabric using either a chemical or heat process and both types of processes will produce the end product of PUL. 

Essentially, fabric + bonded laminate = PUL (polyurethane laminate fabric).

The laminate is what gives the fabric its durable, waterproof properties. Because of this, PUL works wonders as a cloth diaper fabric that traps leaks. 

Specifically, PUL fabric is used in cloth diapers as:

• Covers
• Pocket diapers
• All-in-ones (AIO)
• All-in-twos or hybrids (AI2)

You will also often see PUL fabric used in high chair upholstery, outerwear, wet bags, lunch bags, bibs, mattress covers, and more. 

Polyester is the preferred fabric of choice for PUL in cloth diapers because it repels moisture and creates a more water-resistant product as opposed to cotton which is an absorbent fabric. 

RELATED: Struggling with leaks? Try these tried and true overnight cloth diaper solutions

What is TPU? It’s not a fabric!

There is a lot of confusion around TPU. Essentially, TPU is one of the types of polyurethane films that can be used to make a PUL fabric using a much greener and safer process.

See, back in the day all PUL fabric was laminated exclusively using a chemical solvent process. Nowadays, most PUL fabric is laminated with TPU film using a thermal heat process. They’re similar, but thermally laminated PUL using a TPU film is a much simpler, cleaner, and more efficient process. This newer process using TPU creates a PUL that is stretchier, softer, plasticizer-free, hypoallergenic, non-toxic, and anti-microbial.

TPU labels on cloth diapers

When you see TPU, brands are distinguishing that they used the heat bonding process, rather than the old chemical-ridden process. However, this is just a marketing term. The label PUL does NOT mean that brands labeled as such have used a chemical solvent process for their PUL. In the end, all cloth diapers labeled TPU is PUL.

Heat is the standard method for processing PUL for cloth diapers today, so it is usually the same thing when you see TPU on a diaper cover and PUL on another. When in doubt, the only way to know for sure is to ask. 

The difference between PUL and TPU

PUL and TPU are not two separate materials. Simply put, TPU is a film used to laminate fabric using a heat process, whereas PUL is the final laminated fabric, despite what bonding process or PU film was used. TPU is a part of most PUL fabrics we see today, but not all PUL fabrics use a TPU film.

Picking PUL or TPU diapers

You will see that some diaper brands source PUL from China, while other brands use PUL made in the US. This matters because all PUL manufactured in the USA is now made using TPU and the thermal lamination technique, but PUL that comes from overseas could still be solvent laminated. 

There is no way to know for sure if the PUL was processed using heat or chemicals unless you ask, or if TPU has been listed specifically in its product description. Also, if the PUL was sourced in the USA, it’s a good bet it’s been thermally bonded without the use of chemicals. 

RELATED: How many cloth diapers do you actually need? Find out here!

Pros and cons of TPU PUL in diaper covers

Pros of using cloth diaper covers with thermally bonded PUL:

• Durable & tear/puncture resistant
• Flexible, waterproof material keeps wetness inside the diaper
• Comfortable for the baby
• Somewhat breathable
• Easy to clean

Cons of using cloth diaper covers with thermally bonded PUL: 

• Usually non-biodegradable due to the fabric used
• Synthetic (some babies are more sensitive to synthetic materials)
• Not as breathable as other all-natural alternatives like wool
• Can delaminate early with improper care

All-natural alternatives

Interested in an all-natural solution rather than synthetic? Wool diaper covers (aka wool soakers) are the best way to go. I wrote a post all about wool diaper covers and my favorite picks that you can read to get a feel for them. 

In my opinion, wool is the best kind of cloth diaper cover for so many incredible reasons! My super heavy wetter had fewer leaks with wool. I personally use a combination of wool and TPU PUL covers. Wool for at home and PUL for when we’re on the go.

Though not all-natural, another alternative to PUL diapers for babies is fleece covers. Fleece doesn’t hold as much liquid as wool and is more prone to compression leaks. Fleece and wool both offer a bulkier fit than PUL covers, but you can use wool or fleece longies (pants) in place of a cover for a trimmer look.

Frequently asked questions (FAQs)

Is TPU PUL biodegradable?

This depends on the fabric and laminated film that is used. Some TPU is biodegradable (but not all), so when biodegradable TPU is thermally bonded with a biodegradable fabric like cotton, it can be considered biodegradable. However, it’s important to consider any other materials used in the end product to determine if it’s really biodegradable as a whole unit. 

PUL is not biodegradable when you laminate biodegradable TPU to a fabric that is not biodegradable like polyester, which is what’s most commonly used in cloth diapers.

Is TPU PUL more environmentally friendly?

Yes, PUL laminated with TPU film is manufactured in a much more environmentally friendly way than solvent-laminated PUL. 

What is delamination in PUL?

When PUL begins to break down from certain chemicals, old age, or general mistreatment, delamination can happen. The laminate starts to separate from the fabric, bubbling up and appearing like a peeling sunburn. You will start to notice leaks from those areas as well. 

To protect against early delamination, use proper care when washing PUL fabric. Though PUL is very durable and tough, certain practices will drastically reduce its potential lifespan. 

How to avoid early delamination in diapers:

• Don’t use wash temperatures hotter than recommended by the manufacturer.
• Avoid laundry additives: bleach, fabric softeners, dryer sheets, or even vinegar.
• Use a zero-residue detergent.
• Add an extra rinse cycle to remove all traces of residual detergent.
• Air dry or use a low-heat setting in the dryer.
• Avoid direct sunlight.

What does TPU stand for?

TPU stands for Thermoplastic Polyurethane.

Bottom line: is TPU better?

You know now that when someone says they like TPU better than PUL for their cloth diapers, it’s an incorrect and even irrelevant statement. TPU is just part of most PUL fabrics!