Repairing wool underwear, with a focus on KNEES

I've received several questions about repairing wool underwear, especially the knees. It's not uncommon for thin garments to fall apart MORE when trying to repair them; it happened to me in the beginning too, but now my repairs last longer. So, here's a list of tips and guidance that I hope will help you find a method that works for you without too much trial and error.


The repairs I do myself often take a while, but with less intricate designs and slightly longer stitches and more repetition of what works instead of constant exploration of new designs, these tips can also lead to relatively quick and durable repairs.

1. Don't use too thick thread, as it can damage/tear new holes.

• If you use embroidery floss/stranded cotton for sewing, it can be split so it isn't too thick.
• If you use darning thread from Scanfil, which can be a bit thick for the thinnest garments, adjust the needle (see point 10).
• Feel free to use darning thread from Not Another Hat; it's unraveled from old garments and comes in many different thicknesses, often thinner than what's found as ordinary darning yarn.
• Kogin thread is also cotton and can be split like embroidery floss.
• If you've inherited sewing equipment or found something at a flea market, you might be lucky and find lovely cotton/silk blends or other materials that are great for repairing wool underwear.

2. Use a thin needle with a long eye and preferably a rounded tip, so you hit inside the stitches and not straight through the threads in the fabric of the pants. If you're doing a bit of embroidery-like work, with many small stitches in different directions, I recommend a "tapestry needle" size 20 and up (higher number = thinner), but if you're darning or sewing on patches with long rows of running stitches, long darners, "long darners" can be good. Size 3/9 for the thinnest wool garments.

3. For knees, it's best to patch, as there are often very large worn areas, so darning can be a bit too much work.

4. Patch with thin fabric! Thick patches will have too little flexibility compared to the garment and won't move/give way with use, often resulting in holes right above the repair. If you need something really thick, for children who do pirouettes on their knees, for example ;), then layer several patches on top of each other, in different sizes, to create a graded transition.

5. Repair far enough beyond the hole; the fabric is often thin and worn far beyond the hole itself. Consider the size of reinforcements on the knees of winter suits, for example.

6. If you build up with multiple patches, some can be on the inside and some on the outside. For example, have the largest ones inside, and just cover the hole at the end with a small patch on the outside, which is then fastened straight through the layers and mainly attached to a patch, not to a thin, worn fabric!

7. You can sacrifice a garment and make patches from it, giving you thin wool that matches the garment being fixed. Thin wool socks can also work, but thin wool socks themselves are quite a bit thicker than much thin wool underwear.

8. When attaching the patch(es), it can be beneficial to sew many rows or circles or similar with running stitches, rather than just securing around the edge. This distributes the stress of the patch outwards instead of everything "hanging" on the top stitches, which makes the garment very vulnerable right there.

9. I do not recommend using Vliesofix on such thin items; it can become quite stiff, which can make it uncomfortable to sew, and it can become stiff, causing it to tear around the repair during use. To secure while you work, you can sew some long basting stitches, use safety pins (or straight pins while you baste), or spot-attach with a glue pen.

10. Start from the center and work your way outwards so you don't end up with a large lump of worn, stretched fabric in the middle. You can make a cross first and work outwards from that.

11. If it's very stretched and worn, it might be wise to cut away the worn part or at least put the patch on the outside so that any lumps from the stretched fabric end up on the inside (but patches on the inside are often good because it results in a very discreet repair!).

12. Sewing rows of running stitches can go quite quickly! Especially if you don't do them one at a time. Feel free to be inspired by sashiko, and how many stitches are sewn at once (See video post about sashiko here, jump to 12 minutes to see the sewing technique). You don't need to have exactly the same technique or thimble work, but see if you can find a way to incorporate sewing long rows in one continuous motion.

13. Is it hard to pull the fabric over the needle eye?
Try changing to a slightly larger needle. This seems counter-intuitive, but the needle paves the way for the thread, so if there's resistance at the transition between needle and thread, the needle needs to be larger and/or the thread thinner, so you get a smooth transition and the needle can do its job.
You can also try to sort of push/slide the fabric over the needle rather than trying to pull the needle out of the fabric. It's gentler and more controlled.

14. Don't sew too tightly! It's always better for it to be a bit too loose than a bit too tight. When you turn and sew a new row, it can be advantageous to have a little extra looseness exactly where you turn, a small extra loop so that the fabric can move and stretch without the non-flexible thread "holding back" and creating strain.

12. You can also darn. The same tips apply: don't sew too tightly, use an appropriate needle and thread thickness, and repair far beyond the worn area!
To learn more about darning, you can watch this video (from 9:30 min).

I hope these tips help! Do you have more tips or questions? Please share them so this guide can become even better!

This is a small hole on the butt, but the method can be transferred to larger repairs.

Instead of sewing around the edge, the stitches are extended outwards, meaning the threads help bear the weight of the patch, not just the fabric around the edge of the patch.

Patch on the inside of a sock, shooting stars covering the holes on the front.

More holes often appear with use, which can then be covered by new stars, but the holes are now just wear and tear that doesn't affect the garment's function, and because the patch is attached over a large area with many stitches, a small hole or worn area won't suddenly become a large tear. The garment is reinforced and can be worn further without needing immediate repair.

Patches on the inside are very discreet and neat. Here, the holes are covered with small flowers, while the patch reinforces the thin, worn area.

Many different techniques have been used on these pants, because I like to try different things. This doesn't mean all techniques are the fastest or most durable. My repairs are continuous exploration and experimentation. The tips above are what I've learned from these attempts, but I have yet to perform a repair that follows my own tips to the letter!