If you have ever stared at a ball of size 40 crochet thread and wondered if you actually have the patience to work with something that thin, you aren't alone. It looks like a cobweb compared to the chunky wools we usually see in the craft store, and let's be honest, it can be a bit intimidating at first glance. But there is something almost magical about the way this specific thickness—or thinness, really—transforms a simple stitch into something that looks like actual lace.
For most of us, size 10 is the "standard" for thread crochet. It's what people use for big tablecloths or those classic ruffled dollies. But size 40 crochet thread is a different beast entirely. It's significantly finer, and while it takes a bit more focus to handle, the results are so much more delicate. If you're looking to step up your lace game or try your hand at micro-crochet, this is exactly where you want to be.
Understanding the Scale of Things
One of the weirdest things about crochet thread is that the numbering system works backward. If you're used to yarn, where a higher number usually means a thicker strand, thread will throw you for a loop. With thread, the higher the number, the thinner the strand. So, while a size 3 or 5 is pretty beefy, size 40 crochet thread is getting down into that "very fine" territory. It's not quite as microscopic as size 80 or 100 (which basically looks like sewing thread), but it's definitely thin enough that you'll want to make sure your lighting is good before you start.
Why use it? Well, it's all about the detail. When you use a thicker thread, your stitches are visible, but they have a certain "chunkiness" to them. With size 40, those stitches become tiny points of light. You can create incredibly intricate patterns that just don't work with thicker materials because the "bulk" of the thread gets in the way of the design.
Finding the Right Hook
You can't just grab your favorite 3.5mm ergonomic hook for this. Working with size 40 crochet thread requires a steel hook, and it's going to be a small one. Usually, you're looking at something in the range of 0.9mm to 1.0mm. Some people even go down to a 0.75mm if they have a naturally loose tension.
If you aren't used to steel hooks, they can feel a bit strange. They're thin, they don't have much flex, and they can sometimes cramp your hand if you grip them too tight. I always recommend finding a steel hook with a padded handle or sliding a foam grip over a plain one. It makes a world of difference when you're working on a project that requires a few thousand tiny stitches.
Perfect Projects for Fine Thread
You might be wondering what you'd actually make with something this small. You probably don't want to crochet a full-sized bedspread (unless you have a decade of free time and the patience of a saint), but there are so many cool things that only look "right" when they're made with size 40.
Handkerchief Edgings
This is the classic use for size 40 crochet thread. If you take a plain linen handkerchief and add a tiny, scalloped edge with this thread, it instantly looks like an heirloom. Because the thread is so fine, it doesn't weigh down the fabric or make it pucker. It just looks like it grew there.
Micro-Crochet Jewelry
Micro-crochet is a huge trend right now, and size 40 is basically the gold standard for it. You can make tiny flowers, leaves, or even miniature animals that can be turned into earrings or pendants. If you tried to make a pair of earrings with size 10 thread, they might end up looking a bit heavy or "crafty." With size 40, they look like high-end boutique jewelry.
Delicate Snowflakes
Every year around the holidays, I see people making crocheted snowflakes. The ones made with size 40 crochet thread are always the ones that stand out. They look like actual frost crystals. When you stiffen them with a bit of fabric stiffener or starch, they hold their shape perfectly and look incredibly intricate on a Christmas tree.
Tips for Keeping Your Sanity
I won't lie to you: the first time you try working with such a thin material, you might want to throw your hook across the room. It's a bit of a learning curve. Here are a few things that helped me get used to it.
Check your lighting. This is the big one. If you're working in a dimly lit living room, you're going to struggle to see where your hook is supposed to go. I highly recommend a neck light or a bright desk lamp. Some people even use a magnifying glass stand, though that takes some getting used to.
Watch your tension. It's easy to pull too tight because the thread is so thin, but that just makes it harder to insert the hook on the next row. Try to keep a light, even touch. If you find your hands hurting, take a break. Working with fine thread uses different muscles than working with bulky yarn.
Contrast is your friend. If you're working with white size 40 crochet thread, try putting a dark cloth over your lap. It makes the white loops pop so much more clearly. Conversely, if you're using a dark thread, wear light-colored pants. It sounds simple, but it saves so much eye strain.
The Importance of Blocking
If there is one thing you absolutely cannot skip when using size 40 crochet thread, it's blocking. When you're finished with a piece, it's probably going to look like a crumpled, shriveled-up mess. Don't panic! That's just the nature of fine thread.
Because the thread is so thin, it reacts strongly to the tension of your stitches. To see the true beauty of your work, you have to wet-block it. You soak the piece, gently squeeze out the water, and then pin it out on a blocking mat. You'll be amazed at how the pattern "opens up" once it's pinned. Those tiny loops and chains will stretch out into the beautiful lace you were aiming for.
Why Quality Matters
When you're putting this much effort into a project, you don't want to use cheap thread that's going to fray or snap. Most people stick to mercerized cotton. The mercerization process gives the thread a bit of a sheen, makes it stronger, and helps it resist fraying. It also takes dye really well, so you can find size 40 crochet thread in some really stunning, vibrant colors.
If you find a vintage ball of thread at a thrift store, give it a little "tug test" before you start a project. Old thread can become brittle over time. There's nothing worse than getting halfway through a doily only to have the thread snap because it's forty years old and hasn't been stored properly.
Final Thoughts on Small Stitches
Working with size 40 crochet thread isn't about speed; it's about the process. It's a slower, more meditative way to crochet. You can't really "mindlessly" crochet with thread this thin while watching an intense movie—at least I can't. It requires your attention, but that's also what makes it so rewarding.
There is a real sense of accomplishment when you finish a piece and realize you've created something that looks like it came from a different era. Whether you're making a gift for someone special or just want to challenge yourself to learn a new skill, grabbing a ball of size 40 thread is a great way to go. It might be tiny, but the impact of the finished work is huge. So, grab a tiny hook, find a bright window, and give it a shot. You might find that you actually prefer the tiny stuff over the big, bulky yarn after all.