Tips for Sewing with PUL or TPU

Here's some sewing with PUL or TPU fabric tips and tricks!  It can get tricky at first, but a couple tips goes a long way with fabric this unusual.

PUL/ TPU Facts

What is PUL? PUL is short for Polyurethane Laminate. PUL is a breathable, waterproof fabric heavily used in cloth diapering. Typical PUL has one side a solid color stretchy polyester knit. On the other side of the polyester is the lamination. The lamination is clear, shiny, stretchy and flexible, and completely waterproof. It doesn't contain vinyl or phthalates. It is generally regarded as safe to use against baby's skin, however, exposed PUL next to the skin will feel 'sticky', and can be uncomfortable for some children. It’s debatable whether or not it’s safe to use for food storage.

What is TPU? 
This is where it gets a little tricky.  Originally, all PUL was produced using a chemical laminating process.  TPU is short for a Thermoplastic Polyurethane, which is a process that produces a similar fabric to PUL.  It has polyester on one side and a polyurithane laminate on the other. However it uses a heating and pressure to apply the laminate to the fabric.  Technically, a TPU fabric still is a polyurithane laminate, in that it is laminating polyiurthane to the fabric.  Colloquially, we use the names now to refer to the different types of fabric that come from the different processes.

What's the difference between 1mil and 2mil? 'Mil' refers to how many thousands of an inch thick the laminate is (also called a 'thou'). Either 1mil or 2mil is fine for making diapers. Which you choose is personal preference, both just as waterproof. PUL with 1 mil lamination has more of a drape, stretches more, and is usually cheaper than 2mil. The stretch and drape between 1mil and 2 mil are significant enough that you can feel the difference in the finished diaper. Generally, 2mil is used for large wetbags.  
Where can I buy PUL/TPU? PUL was traditionally bought from Fabrite, but as of Spring 2010, Fabrite stopped production to make their lamination process more eco friendly. As of late spring 2010, JoAnns Fabrics carries PUL.  Quite humorously, the original PUL Jo-Anns  produced were printed on the wrong side.  Pairing with "Babyville", Joanns got it right and offers a small selection of PUL   (They also carry FOE, Polyresin snaps, and Hook and loop Tape)  A word of caution though, some people have experienced delamination with the PUL after only the first wash.  If you need the PUL right away, you can shop at any online diaper supply store.

Where can I get cute Printed PUL? Often, the companies that produce PUL often have little to no cute printed PUL to sell.  Many co-ops offer 'DIY Lamination' services to meet the minimums required to have fabric laminated by the company. You send the co-op your fabric (or buy the prints they are co-oping) and they sew it all together into one big bolt and send it to the company. The prices get pretty expensive quickly with all the shipping costs, cutting, and lamination fees involved. If you want to skip the hassle, you can purchase printed PUL from stores online that have done the work for you. Check out Hyenacart and Etsy as well as traditional online stores for great prints. Make sure the base fabric is 100% polyester, not cotton!

If you do want to have laminate your own fabric, it can be difficult to find cute polyester fabrics to DIY. Although tempting, do not use cotton prints instead of polyester. Cotton wears faster and has a much greater chance of wicking. If you reeaaallly want to use a cotton print, you can by a durable water repellent spray (DWR), and spray the top of your cotton print to reduce wicking. Co-ops can be a great place to find cute printed PUL fabric - many do custom polyester designs suited perfectly for diaper making, and buying right from the co-op saves some shipping and cutting costs.

Sewing with PUL Tips and Tricks

Sewing with PUL can be very tricky, especially when sewing wetbags. The laminate side can be very slippery when gently moving across a smooth service, but very sticky when firmly moving across the same service. This can make difficulties with both sewing and cutting. Plus, using pins in a traditional way is not recommended as it creates holes in the waterproof barrier.  

Tips for cutting/fastening PUL
  • Cut with the polyester sides together
  • Use pins on the edge of the seam allowance
  • Use hairclips to hold pieces together
  • Use a washable glue stick to temporarily baste two sides together (works great!)
Tips for Sewing Sticking PUL

If you're having difficulty sewing two layers of PUL together, it's most likely because the top layer of PUL is getting stuck to the foot of your sewing machine. This causes unusually short stitches, no movement at all, or the fabric bunching up. Here are a few tips to help with that:

1) Use a walking foot (aka. even feed foot).
This foot puts feed dogs on the top side of the fabric and locking to the bottom feed dogs. They cost $10 to $30. I would recommend buying the highest quality you can afford; I've had a few cheap ones that were barely worth the money. I actually bought my sewing machine (Janome Memory Craft 6600P) because it has a built-in walking foot, among other things.
Generic Walking Foot     Janome 6600P Accufeed foot 
A cheap walking foot (left) and a built-in walking foot (right).

2) Use a teflon foot
Also know as a non-stick foot or an ultra glide foot. These feet are slick and allow the PUL to slide by. They cost $5 to $30.
Teflon Foot    Teflon Foot 
A teflon foot
3) Use piece of tissue paper
Place the tissue paper on top of the PUL and sew right through it. Tear it off when you’re done. This technique can be annoying around curves and makes the seams not as tight as they can be, so I wouldn't recommend using it long term, but it works great in a pinch!

Sewing PUL with Tissue Paper     Sewing PUL with Tissue Paper 
Sew, then tear.
All three methods worked well and produced equally sized and spaced stitches.

It's always a good idea to use the smallest sized needle that works for all sewing (to avoid skipped stitches), but it's especially true with PUL. You want to put the smallest holes possible in the PUL to prevent wicking. Start with a (nice and sharp) size 70/10 universal needle and if you're having trouble with skipped stitches, go up on the sizes until you find the right one. If that doesn't help, using other needle types may like extra sharp may work.

Also, always use quality 100% polyester thread (I recommend Gutermann) to prevent wicking.

When topstitching PUL (with shiny sides in), none of the methods above as are nessecary. Just use a regular foot and high pressure. If you have to go right next to snaps, don't allow the foot to lift up over them, as this can cause skipped stitches. Instead, set the needle to the side (still in straight stitch) or use a zipper foot.

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