How to safely bring new-to-you knitwear or yarn into your home
Moths can be beautiful, but clothes moths and wool-eating pests are not what a wool lover wants to see.
Here’s how to make sure your knitwear and yarn are safe.
Not too long ago, a friend of mine suffered through a bout of carpet beetles in her home, which she traced to a piece of thrifted wool knitwear.
Just writing the word “carpet beetle” gives me the heebie-jeebies and reminds me of when my now-teenaged kid was a preschooler. I lived in fear of getting a notice of a lice outbreak at school.
I quickly learned, however, that kids and lice do not equal a dirty or unsanitary home. It's just one of those unfortunate parts of being human. Sometimes, it happens, and so you should simply know how to deal with it or prevent it, as best you can.
Similarly, clothes moths, carpet beetles, or other little creatures that like to eat wool are a fact of knitting life. Having clothes moths (or carpet beetles) does not necessarily mean a home is dirty or unsanitary. Sometimes it simply happens.
When I first conceived the idea for my Swap Shop—a perk for paid newsletter members where we rehome our handmade knitted items that no longer fit us—I kept thinking about how to ensure the knitwear would not compromise anyone’s knitwear or stash. This advice applies equally if you are buying yarn second-hand, swapping yarn, or adding new-to-you yarn to your stash.
I found some solid, well-researched answers for you, because the Internet is full of contradictory advice and flat-out misinformation.
Proactively treat new-to-you yarn and knitwear as if it has a wool-eating critter you can’t see
Whenever you bring knitwear or yarn into your home, whether it's from a thrift shop, resale shop, destash, or our very own Swap Shop, you should ensure—with 100% certainty—that it is free of clothes moths or other eggs so tiny you can’t even see them.
There are lots of articles and forum posts on the Internet with lots of different approaches on how to treat suspected carpet beetles, clothes moths, or other wool-eating critters. I found numerous pieces of advice, without sources, suggesting that you should rotate your yarn in and out of your home freezer, or store it in plastic bags, and let it sit in the sun, or bake it in the oven.
I set out to find actual advice from textile conservators on how to ensure that your yarn or textile is protected from future or further damage.
In the research process, I learned something really interesting: most colloquial advice doesn’t actually protect your wool or treat an infestation.
Lavender sachets and cedar cubes are mostly ineffective at repelling pests.
Most home freezers don’t have a low enough temperature to kill eggs.
Putting yarn in plastic bags, outside in the sun, or a hot car, doesn’t ensure that the yarn or knitwear reaches pest-killing temperatures.
Carpet beetle or moth eggs are so small we usually can’t see them, so a visual inspection of yarn or knitwear is unlikely to tell you if an item is pest-free.
I also learned that all insects and eggs (whether from carpet beetles, clothes moths, or other wool-eating pests) are destroyed at a temperature of 120°F (49°C).
You know what I do at temperatures that high, and higher?
Dye yarn. Wool, even non-superwash wool, can be safely heated at home in water at a temperature of 160° to 185°F (71° to 85°C). Which leads me to recommend the following:
A dyer’s guide to doing a safe, at-home hot water treatment to remove any potential wool-eating critters proactively
This is the process I use on any second-hand knitwear or yarn that I bring into my wardrobe or stash:
Fill a very large pot with cool water. It can also be a pot used for cooking, since you will not be adding dyes or anything other than wool and water to this pot.
Submerge the item in water:
For yarn that has already been wound into a ball or cake: Rewind it into a hank and place two or three figure-8 ties at various spots, to keep it from tangling.
For yarn that is already in a skein (twisted hank) form (the loop, circle, or ring of yarn fastened with knotted ties): Untwist it.
For a knitted item: Submerge it in water.
Leave the hank or knitted item in the water long enough for it to be fully saturated, which usually takes at least 20 to 30 minutes.
Slowly heat the water and knitwear or yarn on medium heat, gradually increasing the temperature until it reaches a temperature hotter than 120°F (49°C). You can use a candy thermometer, but here’s an easier way: When you start to see steam wafting across the top of the water, but it has not yet reached a boil, the temperature is between 160° and 185°F (71° to 85 °C). This is the temperature I prefer for dyeing yarn, and it will also ensure that any wool-eating insects and their eggs are destroyed.
Leave your pot at this steamy, not boiling, temperature for 10 to 15 minutes. Do not stir or agitate.
Turn the heat off and let the water and knitwear or yarn cool to room temperature. I prefer the pot to sit and cool overnight.
Drain the water, wash your pot, squeeze excess water out of your yarn or knitted item, and roll it in clean towels to blot out most of the water. Block your item as usual, or hang your yarn to dry.
This temperature of water (~185°F or 85°C) will kill any larvae of clothes moths, carpet beetles, or any other pest that can damage clothing—even eggs that are too small to see—and this temperature of water will not damage wool. It's the same temperature at which I dye yarn. Just be sure not to boil or agitate, and the wool will not felt.
If you are treating an item of knitwear, rather than yarn, you can also take it to a dry cleaner. However, save yourself the money and save the environment from the chemicals by doing this simple at-home hot water treatment instead.
If you do a hot water treatment of any new-to-you yarn or knitwear you bring into your house, you can be assured that it will not introduce unwanted wool-eaters into your larger stash or knitwear wardrobe.
Should you do a hot-water treatment on new yarn?
I do not, with just a few exceptions:
If I suspect the yarn has been in a sketchy location, I will proactively treat it before bringing it into my home and stash. For example, if I were shopping at a local yarn shop that was very dusty and dirty and looked as if the yarn hadn’t been moved or cleaned in a long time, I might proactively treat it.
Wool-eating critters love to gather in locations that are undisturbed by humans for a long time. I once encountered a shop like this, a tourist yarn shop on Cape Cod, in the 2010s, and it was so dusty and untouched that even remembering it gives me heebie-jeebies.
If there are internet reports of a yarn manufacturer’s warehouse being compromised, I would also perform a hot water treatment on the yarn before adding it to my stash.
For indie-dyed yarn (like the yarn you receive from me), you can safely add it to your stash without a hot water treatment because it will have been recently immersed in water that’s just under boiling temperature as part of the dyeing process.
Most of my yarn is dyed to order, with very little in stock at any given time. This helps me ensure that my yarn stock and stash remain sparkling clean and pest-free.
Bookmark this post and return to it the next time you add a piece of thrifted knitwear to your collection or when you purchase yarn from a destash.
Sources:
I found this NYT Wirecutter article to be extremely helpful, as it includes citations from the Smithsonian Museum Conservation Institute, Cornell University, and the Fashion Institute of Technology. (paywall $)
