Is Acrylic Yarn Flammable?

The regulation, and what it covers

Clothing textiles sold in the United States fall under 16 CFR Part 1610. Its stated purpose is to reduce injury and loss of life by providing standard methods of testing and rating the flammability of textiles for clothing use, thereby prohibiting the use of any dangerously flammable clothing textiles.

It is a clothing standard. It applies to fabric in a form ready for use in wearing apparel, and it excludes hats that do not cover the neck, face or shoulders, gloves up to 14 inches, footwear, and interlinings.

The three classes

The standard sorts textiles into three classes by how fast a flame travels up a sample. The test holds the fabric at a 45 degree angle, applies a standardized flame for 1 second, and records the time taken for the flame to travel 127mm (5 inches) up the specimen.

Class 3 is the one the standard exists to keep off shelves. Notice that only raised-surface fabrics can be Class 2 - the regulation treats a fuzzy or brushed surface as a separate risk, because a surface flash can run across the nap without the base fabric burning at all.

Melting is the real acrylic question

Flame spread is not the same as heat behavior, and this is where acrylic genuinely differs from cotton and wool. The regulation itself distinguishes a base fabric that ignites from one that fuses - fusing being the melt.

• Cotton chars. It scorches and turns to ash, and it does not stick.
• Wool is hard to ignite and self-extinguishes in ordinary conditions, which is why it appears on the exempt list.
• Acrylic softens and melts. Molten synthetic sticks to skin, which is a burn mechanism cotton does not have.
• A raised or brushed acrylic surface is the worst case, because loose fiber ends carry a surface flash.
• None of this makes acrylic clothing unsafe in normal use - it makes it the wrong fiber for specific jobs.

Where not to use acrylic

1. Potholders, oven mitts and trivets. Use cotton, doubled. This is the clearest case, and best yarn for potholders and trivets covers the construction.
2. Anything used around a stove or open flame, including hanging towels.
3. Candle mats and table runners under candles.
4. Costumes with loose, fluffy surfaces, where a surface flash has somewhere to run.
5. Firefighting, welding or workshop wear, which needs purpose-made flame-resistant fabric, not craft yarn.

Where acrylic is completely fine

Blankets, sweaters, hats, scarves, toys and afghans - the overwhelming majority of what acrylic is used for. The fiber is on the regulation's exempt list precisely because all-acrylic fabric passes the test reliably.

If you want the case for and against acrylic on other grounds, acrylic vs wool yarn, does acrylic yarn shed microplastics and acrylic yarn allergies and sensitivity cover the rest.

A note on what this page is not

This is a plain reading of a public regulation, not fire-safety advice and not legal advice. If you are making something to sell, read the standard itself, and note that childrenswear sleepwear falls under separate standards entirely.

Both links in the sources below go to the regulation text - one to the Code of Federal Regulations on govinfo.gov, one to the Electronic Code of Federal Regulations.