What is soft, pliable, and waterproof; can withstand fairly high temperatures; and holds up to a lot of use? Like me, your first guess might have been those dang swimming pool noodles you always buy too many of and then never know what to do with once summer is over. But... the real answer is: PUL, polyurethane laminate if you wish to be formal. The broad category refers to any fabric with a polyurethane laminated to a base fabric. Most common is a polyester knit fabric laminated to a thin waterproof, non-breathable polyurethane backing. Originally developed for use in the medical industry, it's very durable and very popular right now for folks making diapers, diaper covers, changing pads, bibs, training pants, and outside the world of babies, it's often used to create reusable sandwich, snack and lunch bags. As with most man-made fabrics, there are some tips and techniques that make sewing with PUL easier.
We chose the thin, 1.33 mm PUL knit as a waterproof lining for our Baby Gifts: Pretty Bird Quick Trip Diaper Bag. It worked great. There are double laminates out there as well, which are usually the waterproof polyurethane sandwiched between two layers of polyester knit.
We've also used the popular cotton laminates, such as Heather Bailey's Nicey Jane cotton laminate, which we used for our Retro Fun: Toddler's Laminated Project Apron. Though different from PUL, because it's bonded to a natural cotton fabric (it is not waterproof - just water resistant), several of the pinning and sewing tips are applicable to this type of fabric as well.
Needles and pins
Unlike the forgiving fibers of natural cotton weaves, when you make a hole in PUL, it's there for good. Because of this, the fewer pins the better. The more holes you make, the less waterproof a project can become. Many people are against ever using pins on PUL, but I'm not that rigid. If your project is a simple one without a lot of complex interlocking seams, you should try to avoid pins. You can substitute paperclips, hair clips, fusible seam tape, or a glue stick (Pritt Stick is a good one for fabric and it washes out with the first laundering). For more complicated projects, sometimes you just gotta use pins. In that case, try to keep your pinning within the seam allowance. Also, this is a funny tip, but try to avoid mistakes. Because if you have to rip out a seam, the holes will remain.
The thickness of laminate you are using will determine the type of needle to use. A denim or jeans needle is a good choice for thicker laminates in a No. 14 to No. 16. For the thinner laminates, a ball point needle is a good choice in a No. 9 or No. 11. Always test first on a scrap.
Laminate can be 'sticky' going through your sewing machine. That great laminated surface, which is what makes it waterproof or water resistant, tends to want to stick to your presser foot. There are several ways to combat this:
- Use a Teflon® or Ultraglide foot. These feet have a special coating on the bottom, which allows them to move smoothly over difficult fabrics like PUL and vinyl.
- Use a Walking Foot, which has feed dogs incorporated into the foot itself. These feed dogs work in conjunction with the machine's feed dogs to feed fabric layers evenly.
- When possible, sew with the laminate side down against the feed dogs and the fabric side against your presser foot.
- Use a baker's paper or wax paper over the top of the laminate. The presser foot moves across the paper easily, and these papers are translucent so you can still see where you're going. Simply tear it away from the finished seam when done. It's most efficient to work with strips of paper just in the area where you're stitching.
Use a high quality, 100% polyester thread rather than a cotton thread. A cotton thread can wick moisture to the outside.
There are folks in both the zig zag camp and the straight stitch camp. I've found either stitch works fine. The key seems to be to lengthen your stitch. You might also want to loosen your tension slightly. Test your stitch on a scrap before you begin your project! This is always a good rule of thumb, but is especially important when working with difficult fabrics.
Laundering and other care issues
Because PUL fabric was originally developed to withstand the intense heat of sanitizing washers and dryers used in hospitals, it will certainly hold up in your home washer and dryer. In fact, washing and drying with HIGH heat can help to seal up needle holes and seams.
- Use mild detergent
- Do NOT use fabric softeners, chemical stain lifters or bleach
- Do NOT iron
- If you use PUL for a project that stays wet for extended periods (such as with diapers), you can add a ½ cup of baking soda to the wash cycle to prevent odor build up.