How to Sew PUL Fabric
Working with PUL is a bit different from other fabrics. The lamination gives it a bit of heft that makes it easy to handle. Once you get the knack, it is a pleasure to sew. Here are a few tips on how to sew PUL fabric:
No need to prewash
You do not need to prewash PUL fabric. It will not shrink. You can also leave cut edges unfinished; it will not unravel or fray.
While you might be used to pinning fabrics together before sewing, you don't want to make holes in your waterproof PUL. Some ways to hold the layers together for sewing are hair clips, binder clips, or washable glue sticks.
Use a ball point or knits needle
On your sewing machine, you should use a universal, knits, or ball point needle. Do not use a "sharps" needle - these are for cottons only. In this case, you do not want to poke sharp holes in the fabric, you want a rounded tip needle to slide between the fibers of the poly knit. Use a small needle diameter: 70/11, 75/11 or 80/12.
Use polyester thread to prevent wicking
Your thread should be 100% polyester. Make sure it is NOT cotton coated polyester - this can leads to moisture wicking along the seam line.
Sew with the coated side against the feed dogs
The laminate side of the fabric can stick to your presser foot. Sew PUL with the laminate side down. If you must sew laminate side up (for instance when making a wet bag), use a teflon foot, a walking foot, or lay thin paper over your seam.
No need to "heat seal"
It is not necessary to "seal" the seams of PUL items in a hot dryer prior to use, and this practice could potentially damage your fabric. If desired, an impulse sealer may help seal seam allowances. A french seam is another method to prevent moisture leakage. Consider trying your finished project without sealing seams - often just sewing is enough. PUL is a barrier fabric that protects other surfaces from getting wet or dirty. PUL fabric is not generally meant to make a liquid-holding bag like a canteen.