Single jersey, interlock and rib knit
Short answer: Single jersey is thin and curls at the edge. Interlock is twice as thick and lies flat. Rib knit stretches the most and is used for edges.
Single jersey
This is the simplest knit and the one you find in almost every ordinary t-shirt. The right side faces one way and the wrong side faces the other. It is thin, light, and cool to wear, but a free edge always curls toward one side unless it is sewn down or folded over.
Interlock
Interlock is two layers of jersey knitted together into one fabric. It is thicker, smoother on both sides, and does not curl at the edges at all. That is why it is often used for underwear and sleepwear, where the edge needs to lie flat against the body without bothering or scratching the skin all day.
Rib knit
Rib has vertical ridges and can stretch a great deal across the width without becoming stretched out too quickly. It is used for neck edges, cuffs, and sock tops, meaning everywhere the fabric needs to give and then pull itself back. See bamboo socks for women. Without rib, these edges would sit loose after a short time of use.
How to choose
For thin t-shirts, jersey is the right choice because of its weight and cooling effect. For underwear and sleepwear, interlock is often more comfortable because it does not curl. See bamboo sleepwear for women. Rib is rarely the whole garment, but almost always the edges, regardless of which of the other two types the rest is knitted in.
Weight and warmth
Interlock is warmer than single jersey, because the two layers trap more air and insulate better against cold. Jersey, in contrast, is cooler and lighter, which makes it a better choice during summer months or for layers worn close to other garments, where extra warmth is not what you want.
Look on the wrong side
You can often spot the difference by looking at the wrong side of the fabric. If the wrong side looks the same as the right side, it is usually interlock. If there is a clear difference between the two sides, it is single jersey. See bamboo underwear for women. This simple test takes only a couple of seconds and needs no tools.
Wear resistance
Interlock generally withstands more handling than single jersey, because the two layers support each other and spread the load better through the fabric. Jersey is more prone to pulled threads, especially at a free edge. That is one reason interlock is often preferred for garments that get washed and worn intensively.
Price difference
Interlock typically costs a bit more to produce than single jersey, because more yarn is used and knitting time is longer for the same area of fabric. This is rarely a large factor in the price of the finished garment, but it is part of the reason an interlock piece can cost slightly more than a comparable jersey style.
Combining knit types
Many garments actually use several knit types at once. A piece can have a body in jersey, edges in rib, and possibly a reinforced section in interlock where wear is greatest. The combination gives the best of each type while keeping the price down by using the most expensive fabric only where it counts.
Frequently asked questions
Can you tell the difference by eye
Yes. Look at the wrong side of the fabric. If it looks the same on both sides, it is interlock. If there is a clear difference, it is single jersey.
Which one is warmest
Interlock, because two layers trap air and insulate better. Jersey is the coolest and therefore often the preferred choice for light summer garments.
Why does jersey curl
Because the two sides of the fabric are knitted differently and carry different tension. That uneven tension means a free edge always pulls toward one side.
You can find the full range at Bamboo-Clothing.com.
