How to determine the stretch percentage of your fabric
Most lingerie items these days will use stretch fabrics (including Sew Projects patterns) so in order to sew lingerie items you need to know how to determine the stretch percentage of your fabric. This is crucial in getting the correct fit so it can’t be overlooked.
Thankfully this is quite simple to do.
Firstly you need to cut a 10cm by 10cm swatch of your fabric you are going to work with. Make a note, or indicate what way the selvedge (or warp and weft if you prefer) would be as you will need to know this when cutting out your patterns.
You need to line the beginning edge up on a cutting mat at 0, or beside a ruler if you don’t have a cutting mat. Firmly hold the fabric down at 0 and with the other hand, holding as close to the edge as possible, pull the fabric as far as it will reasonably go. Look at where the edge reaches to. For every 1cm it stretches to it equals 10% stretch, so the main stretch, perpendicular to the selvedge on this jersey had a 40% stretch as it stretched to 14cm.
The other way only had a small or almost no stretch, so I did not have to test this side.
The stretchier side (main stretch) needs to go around the body (horizontally). Therefore you need to establish which way has the most stretch, especially if both ways are stretchy. For this stretch mesh/power mesh fabric, follow the same principle but test both ways. In the above photo, the side along the selvedge had the most stretch at 35% and the side perpendicular to the selvedge only had 20%. So if the pattern tells you to use the most stretch horizontally around the body, lay the patterns with the main stretch going the same way as the selvedge in this case.
Another point to say about stretch fabric is to observe the fabric carefully. Some fabrics are stretchy but their stretch retention is very poor, meaning when stretched out, the fabric will not go back into its original size. It’s unlikely these fabrics will be suitable for lingerie, as you need the fabric to hold its shape well!
If you have any queries on fabric stretch percentage, drop me an email and I’ll be happy to advise you.