How To Choose A Garment To Felt On
So you'd like to start customizing your wardrobe with needle and wet felting, and you're wondering what kinds of garments to use?
You can actually felt on most fabrics! The most important thing is that it's strong enough to take being stabbed with a barbed needle, is washable, and ideally can be ironed on a steam setting. You'll also want to be aware of fabric thickness.
Here's why those things are important:
Fabric strength: if something is too thin, needle felting may create more holes than it repairs. If you'd still like to try felting on a thin fabric (hoodies, t-shirts, sweaters as thin as t-shirts), I'd suggest using a #40 needle, felting more slowly and less aggressively and NOT using a felting machine.
Washability: I nearly always wet felt my designs when they're going to be on something that's worn or washed. Wet felting is like a controlled washing, and it tangles the fibers together on both sides of the fabric, really locking them in place. You can also choose not to wet felt, as your design should still last a long time. It may pill more, or rip out more easily, and just have a bit of a different texture. I don't always wet felt scarves, as they are nearly never washed and don't tend to be treated roughly. If your garment isn't washable but you still want a wet felted design, I'd recommend felting onto pressed wool felt and using that as a patch you can sew on.
Ironing on a steam setting: This is most important for garments you want to wash in the washing machine, because if you ever accidentally wash it in hot water and shrink it, ironing on a steam setting with flatten out your design and restore it to it's former state. However, I like to iron all my designs as it helps them stay looking nice and crisp. Since felting is "tangling, compressing and matting" of fibers, ironing helps to felt it more by compressing them.
Fabric thickness: The thickness of the fabric affects how easy it is to felt on. Fabrics that are "too thick" will take longer to work with, and fabrics that are "too thin" will also take longer. Cashmere sweaters tend to be on the thinner side, and cable knit ones tend to be on the thicker side.
Here's an overview of different garments and fabrics:
Wool sweaters: These are the easiest to felt on. The wool roving will tangle and grip more easily to the wool fabric. They are hand wash friendly, and you can iron them on a steam setting.
Cashmere sweaters: I'd say these are the second easiest to felt on! I love working with cashmere sweaters because they're so soft, and feel great to wear. The only thing that makes them slightly more difficult is the the fact the fabric is normally pretty thin. Fabric that is "too thick" or "too thin" just takes longer to needle felt on, because it takes more time to work the fibers in. These sweaters often say dry clean only and no iron, but I've never had any problems hand washing them or quickly ironing designs.
Pants (wool, cashmere, synthetic, jean): What you want to look out for is not putting felting anywhere that is constantly pressed/rubbing against the skin. I repaired some cashmere pants that had holes on the thigh, but found it to be itchy and uncomfortable to wear for long periods of time, especially if i'm sitting down. You could also wear leggings or shorts under any pants with designs on the upper legs. I think the easiest place to felt on pants is from the hem up to the knee. The other thing, is that pants get washed a lot more than sweaters, so remembering to wash on a cold, gentle setting is important. It would also be good if the pants you chose can handle being ironed on a steam setting, so if it DOES get washed in hot water, you can relax and flatten out the design with the iron.
Wool blend sweaters: These tend to be similar to wool sweaters, as they have enough wool to be a bit grippy, and perhaps enough of something else to be softer. I'd just caution you to remember that some synthetic blends can't take being ironed.
Cotton sweaters: These take a bit longer to felt on due to the fact that cotton isn't grippy. But they're still great sweaters to use as they can easily be washed and ironed.
Synthetic sweaters: These tend to be a bit easier to work with than cotton sweaters, especially if they're a bit fluffy as that's more grippy. The difficulty with synthetic sweaters is they shouldn't really be ironed, since you could melt the plastic. That means it's better to just handwash these since machine washing can sometimes shrink the design and require ironing to flatten it out again.
Jean jackets/denim: These are great to felt on as the fabric is really strong and can take being felted, and it's not a piece of clothing that gets washed very often. A warning: it's very hard to felt on the seams because they're so thick. I tend to avoid them for that reason, but if you're ok to break needles it's possible to do. They're also hand wash and ironing friendly! However, they do take a very long time to felt on because the fabric is pretty thin, and isn't grippy since it's cotton. You need to spend a long time making sure your design is totally flat, so just be prepared to take a long time to do that. (if it's a whole back design, I'd say upwards of 3 hours if you don't have a felting machine)
Hoodies: I've found these tend to develop a few holes when felted on, but it's mostly in places that have been felted "too much." You can still felt on hoodies if you take your time and use lighter felting needles, either #40 or a #38 that's on the lighter side (I find #38 felting needles tend to vary in actual size a lot depending on where you by them) and don't use a felting machine. I'd also recommend pulling it off the felting board more often, since getting it too attached to the board and then pulling it off could damage the fabric. But if you don't mind the possibility of a few holes in your hoodie, I wouldn't worry about it and I'd treat it like any other sweater.
Socks: Felting on wool or wool blend socks works great, and isn't itchy like felting touching the neck or thighs. You will need to create a new felting pad to fit inside them, and I'd suggest cutting up a grouting sponge for this. Since socks are washed so often, it's better if these are handwash only. If you don't mind your design becoming a bit blurry though, you can also toss them on in the machine on a gentle, cold cycle.
Scarves: I love felting on cashmere or wool scarves. I'd suggest only felting on the ends so the fibers of your felted design aren't pressed against your neck, but if you're repairing holes in a scarf I'd just suggest trying it and seeing if it's uncomfortable or not. I don't always wet felt these designs since they don't get washed often and aren't getting a lot of wear and tear.
Leather: Felting on leather wouldn't work for several reasons. First of all, the needles aren't strong enough to punch through nearly every leather I've see or worked with. Second of all, leather doesn't have a weave so you would just be punching holes in the skin that would stay there and affect the structural integrity. You could do something like punch a bunch of holes in a piece of leather with a stitching fork and felt only into those holes but that would be super difficult. If anyone ever tries that please let me know.
Pressed wool felt patches for more delicate or non washable items: for non washable items or something like leather, I like to make a needle felted patch on a pressed wool felt backing and then sew it on. Pressed wool felt is also one of the easiest things to felt on so it's perfect. I've found that synthetic felt is really hard to felt on, but if that's all you have on hand it would work! I've also used cotton fabric as a backing for a patch, which is easy to felt into but you get left with the problem of frayed edges. I've fixed that before by wrapping wool around the edge, it's just pretty time consuming.
So, what's the easiest garment to felt on? Probably a medium weight wool or wool blend sweater. But don't let that stop you from felting on other fabrics too!! It might just take a bit longer.
Let me know if you have any more questions in the comments!