When you pick a sewing pattern to start for your next project, you’ll pick your fabrics and hardware first because those give the bag it’s unique style and finish. But what’s underneath the exterior of the bag, the bones of the bag, are what’s going to make the bag hardwearing, functional, and make sure the bag keeps those good looks and shape for as long as possible.
Most patterns will usually suggest recommended interfacing and stabilisers based on the designers own testing and examples, and those of the pattern testers. Sometimes, however, you may not be able to get a particular recommended product in your area, or you may decide to change up one or more of the interfacing products to make the bag softer, firmer, more or less flexible etc.
Perhaps you are using a type of fabric other than the one used in the example bags. Many bags are sewn with quilting cottons, and an increasing number of patterns these days call for a heavier cotton or fabric, such as a canvas or a home decor weight. In order to get the same result on both fabrics, you would need to apply a different weight of interfacing.
Having experience of a range of interfacing, foam and stabilisers makes you a better sewer when it comes to bag making. You can make your own informed choices about which interfacing is going to work best with your chosen fabrics and materials, even if that differs from the designer’s recommendation.
Here’s a handy video showing several different types of interfacing. It’s a few years old now and there are more products on the market now that weren’t covered in the video, but this is still a great place for beginners to bag sewing to start to learn about all the options and how they vary.
Deby used to make great sewing videos and patterns when she wrote for the So Sew Easy sewing blog, and even made a class on Craftsy/BluPrint for Sewing Wallets a few years back. She had to retire from sewing a few years ago following some bad health which was a loss to the online sewing community. We still keep our fingers crossed she’ll come back one day and share some more tutorials and easy to sew patterns with us.