To make the Safran pants, you will need a woven fabric, medium weight (6oz/yd² minimum), with 20% to 30% stretch. The stretch factor is really important, as it ensures you will be able to put on your pants, bend your knees, sit down, and do all kinds of other useful activities 😉
To have enough stretch and recovery, the fabric needs include lycra/spandex in its composition. Unfortunately, the stretch factor of a fabric depends of a variety of parameters: weave, composition, thickness… and the spandex percentage is not proportional to the stretch factor (we have found fabrics with 25% stretch that only have 1.4% spandex, and others having 4% spandex with only 10% stretch).
If you already have stash fabric that might be suitable for Safran, or you want to buy some in a shop, here is how to measure its stretch percentage:
Cut out a rectangle of fabric that is 10cm (or 4″) wide in the direction of stretch, and at least 5cm (or 2″) high. Hold both ends firmly, stretch the swatch as much as possible, and measure its new width: it should stretch by 2 to 3cm, or 7/8″ (10cm x 20 / 100 = 2cm).
Obviously, you can’t just cut out your own swatch in a store! Bring a ruler with you, and pinch the fabric between your thumbs and index fingers, placing your thumbs 10cm (or 4″) apart in the direction of stretch. Keeping hold of the fabric, spread your hands as much as possible and measure the new distance between your thumbs.
This method will give you a good idea of the stretch percentage of your fabric, but keep in mind that the swatch method is more accurate 🙂
If you can’t find the right fabric locally, you might be tempted to buy it online. Unfortunately, as we have seen, it is not possible to use fabric composition to evaluate the stretch percentage! Most online stores do not indicate the stretch percentage (or get it mixed up with spandex percentage), so we have done some research and put out a call to online stores to create this list of tried and true fabrics!
All the fabrics in this list have been tested either by us, by the sellers we have contacted, or by our customers. If you run into a problem with one of them, please let us know so that we can update the list!