You've seen the OEKO-TEX label. It's on bedsheets, baby clothes, and now - increasingly - activewear. But if someone asked you what it actually certifies, most of us would say something like "it means it's safe?" and leave it at that.
Fair enough. Here's the short version: OEKO-TEX Standard 100 tests textiles for over 100 harmful substances - things like formaldehyde, heavy metals, pesticide residues, and certain dyes that are known irritants. The testing is done by independent labs, not the brand itself, and it applies to every component of the product. Thread, fabric, labels, even the silicone grip dots on your socks.
The reason this matters for workout wear specifically is pretty straightforward. When you exercise, your pores open. Your skin absorbs more. Whatever is in your fabric has a shorter path into your body than it would in, say, a pair of jeans you're wearing to dinner. So the composition of something pressed against your skin during a sweaty reformer class is actually worth a second look.
What OEKO-TEX actually tests for
The certification screens for more than 100 regulated and non-regulated substances. That includes formaldehyde, which is used in some textile finishes, heavy metals like lead and cadmium, pesticide residues carried over from conventional cotton, and azo dyes that can release compounds linked to skin irritation.
The standard also sorts products into classes based on how much skin contact they get. Class 1 covers items for babies, which faces the strictest limits. Items worn directly against the skin sit in Class 2 and are held to tighter thresholds than, say, a jacket lining. Socks fall into that direct-contact group.
Testing happens at the component level, not just the finished product. Every thread, dye, and trim is checked, and the certification has to be renewed each year. It isn't a one-time stamp a brand earns and coasts on.
That annual renewal is part of why it carries weight. A brand can't certify one production run, slap the label on everything afterward, and stop checking. To keep using the mark, the materials have to keep passing.
Why this matters for grip socks specifically
Grip socks sit against your skin for the length of a class while your feet sweat and your pores open. That's the exact condition where residual chemicals in fabric have the easiest path into your body.
The grip dots matter here too. On a certified sock, the silicone used for the grip is tested alongside the fabric, not treated as an afterthought. Plenty of brands never certify at all, which doesn't automatically mean their socks are unsafe - it just means no independent lab has checked, and you're taking their word for it.
There's also the dye question. Grip socks come in every color of the studio aesthetic, and color means dye. Certain dyes are exactly what the standard screens for, so on a certified sock the pastel you picked has been checked for the compounds that tend to irritate skin.
How to check if your gear is certified
Look for the OEKO-TEX Standard 100 label with its certification number. You can enter that number on the OEKO-TEX website to confirm it's valid and see what was tested.
One thing worth knowing: "organic" and "OEKO-TEX certified" are not the same claim. Organic refers to how the cotton was grown. OEKO-TEX refers to what's in the finished textile after dyeing and processing. A sock can be one without the other, and the brands worth trusting tend to be both.
Footwrk's Priority Blend uses OEKO-TEX Standard 100 certified organic cotton, so the certification and the organic growing standard both apply. If you want the full picture of what goes into a sock, our materials breakdown walks through every fiber and what it does. You can also browse the range here.