Let’s face it, some of the specialized fabrics most commonly used in cloth diapers are not the easiest to work with. PUL/TPU is one of them, but with a few simple tips and tricks, you can easily master working with this fabric and create beautiful waterproof works of art.
What is PUL/TPU?
The PU in the name stands for polyurethane. A smooth, stretchy, breathable and waterproof membrane that is bonded to a base fabric to create a waterproof fabric perfect for cloth diapers. It is commonly used in cloth diapers, wet bags, cloth menstrual pads and diaper covers.
The difficulty with sewing this fabric usually lies in that is can be thin, slippery, sometimes sticky, and downright finicky. Add to that the fact that you cannot use pins while sewing this fabric (pins poke holes in the waterproofing and will result in the fabric leaking moisture), and it can challenge your patience. But it really isn’t as difficult as it may seem at first if you know a few useful hacks for mastering this material. The following accessories can make sewing PUL/TPU easy and fun;
- Ballpoint machine needles needles
- Good quality polyester thread
- Tissue paper
- Walking foot
Common problems that may occur when sewing with this fabric;
Skipped stitches are quite common when sewing polyester knits, which is usually the fabric that the PU layer is attached to. Use a thin sharp ballpoint machine needle and good quality polyester thread. I recommend size 70 Schmetz Jersey Needles, and Seralon or HGH (SABS approved) poyester thread. All these can be found at most fabric stores around South Africa.
Fabric not feeding through
If you are getting tiny stitches, fabric not wanting to feed through evenly, or sticking to the machine foot, you can use the following; teflon coated machine foot, walking foot or tissue paper. A teflon coated foot will prevent the PU membrane from sticking. A walking foot will help feed your layers of fabric through more evenly. If you don’t have anything fancy like that on hand, sew your fabric with a layer of tissue paper on top. After you have sewn your seams, simply tear the tissue paper off the fabric, and you will have beautiful, even seams. Also sew with the laminated (plasticky) side facing down whenever possible.
PUL/TPU can be very slippery, and because it is not advisable to use pins in your waterproof fabric, it can be difficult to keep layers together when they are so slippery. Wonderclips to the rescue! These nifty little clips hold layers together without damaging or poking holes through the waterproof membrane. These clips are a great alternative to pins for all other types of fabrics too. They can be purchased on the Mini Matters website under sewing notions. Basting spray is another useful tool for keeping layers together. Be sure to get a re-positionable/temporary bond spray suitable for textiles so that you don’t stick your layers together permanently. Always test a basting spray on some scrap fabric before using it on your beautiful PUL.