Sewing with bi-stretch fabrics?

Dear users, dear authors,
I found this in the product text of a sewing pattern:
Materials list (for kids' basic shirts)
Jersey fabric, sweatshirt fabric, bi-stretch fabrics
--> What is bi-stretch fabric?

It's about this pattern:

Ebook Basicshirt Kids

Bi-elastic fabric is a fabric that stretches both widthwise and lengthwise. 

Does the fabric stretch out faster then?

Elastic doesn’t just mean stretchy - it also means that the fabric can spring back to its original shape.

If you think of leggings, for example, they need to have at least widthwise stretch. But they also stretch lengthwise, for example when the knee is bent. If the fabric isn’t also stretchy lengthwise, it will lose its shape more quickly.

You can actually use bi-elastic fabric even if you only need widthwise stretch; at least I can’t think of any reason against it. However, bi-elastic fabrics are available as both knit and woven fabrics, so you still need to keep that in mind when choosing your fabric.

There is also jersey that is bi-stretch, and it is not warp-knit fabric but knitted fabric, just very finely knitted. With bi-stretch fabrics, it’s important to pay attention to quality; otherwise, they will eventually stretch out unattractively, because in so-called cheap goods the elastane content is made from inferior material.

Best, Inge

Thanks for your help.
Do you really need bi-elastic fabric for children’s shirts? What are the benefits?

Children’s clothing made with two-way stretch fabrics moves with children and keeps up with everything they do throughout the day without hindering or restricting them—that’s why this two-way stretch clothing is so great for kids.

Best regards, Inge

Oh, I see. That makes sense.

You should always pay attention to what the designer recommends for the sewing pattern. There really are patterns where you absolutely must use a bi-elastic fabric. But for regular children’s shirts, it isn’t strictly necessary.

Best regards,
Sonja

Why would you need fabric that isn’t actually stretchy at all?

Sturdier woven fabric is needed for many things, Josefa—clothing like suits or formal wear, which look unattractive when bulges form due to the stretchy fabric; even for traditional costumes, it’s better to use a non-stretchy woven fabric. Then there are curtains, bedding, etc., which are better when they don’t contain elastane. Workwear is also often better when made from non-stretchy fabrics.

Best regards, Inge

Is fabric science also part of the training?

Yes, it’s called textile science, and it covers a broad spectrum of training—because when you set up shop as a tailor and start seeing customers, you need to know how to give them the right advice.

Best regards, Inge

Did you also receive those little fabric swatch booklets with it? 

No, not officially, but we all got ourselves a folder like that—partly because of the exams we had to take. As an industrial tailor, you have to pass three exams: the first one qualifies you as a seamstress, the second as a finisher, and the third as an industrial tailor.  But we had plenty of fabric in the workshop, and if there were any special weaves, the master tailor would bring in specific fabrics just for that purpose—because during our theory classes, questions would sometimes come out of the blue, like, “What kind of fabric is this?” or “And what about that one?”
To figure that out, you often have to do a burn test: if it crumbles like paper, it’s cotton; if it smells like burnt horn, it’s sheep’s wool; if it clumps, it’s a polyester fiber.

Best regards, Inge

Oh, I see. I thought you could tell just by feeling it.
But the burn test makes sense.