Many resources out there says to use 100% wool, yes this is correct but you must make sure that it is not machine washable wool. Machine washable wool is treated to ensure it does not felt, so however hard or much you rub your work or how hot your water is, it will not felt. When you buy yarn for felting ensure that it is not superwash or sport yarn. Or look out for these symbols below on the washing instructions. Only use 100% wool yarn that requires hand washing.
2. Not too gentle
When looking for tutorials online I found several videos on knit felting where the person in the tutorial puts everything in a bucket and stirs it with a cooking utensil. And then I got confused with other felting (from roving) videos where the person says that you need to be gentle. Fortunately with crochet items you can work your item with some force and don't have to worry too much with being gentle. I normally rub my items folded so that there is enough friction and agitation to make the stitches felt. Yes when it is hot it will get out of shape a little, but the item will harden. (I will cover this in more detail in Part 2)
3. The correct stitch is HDC and a large hook
One particular tutorial video said to use only single crochet. However I found that this don't work. I learned from forums that single crochet does not give the stitches enough room to move against each other. And if you think that a smaller hook would mean less gaps, you are wrong (just like I was!). Again smaller hook will make the stitches too close for enough agitation to happen. So your finished crochet item should be a bit loose with only half double crochet stitches, like below.
4. Felt with hand and soap
You need to use soap as it helps to get those fibres locking to each other. I actually put the piece between my two palms and a little hand soap (since it's softer on the hands) and rub. Yes there will be suds and you don't have to worry about them, they will be rinsed off when you are done with felting. If you have sensitive skin, make sure you moisturise after or use gloves.
5. Use really hot water
I do use boiling water on my crochet pieces and it help to speed up the process. Do not use your bare hands with boiling water it will burn your skin right off! Use a potato masher to agitate your piece then let it cool down to a comfortable temperature before using your hands. One thing to keep in mind is some wool gives out a smell when you are working with hot water on it. It smells like dye (some colours will bleed), you do not want to breathe in too much of this as it could give you a mild headache. So when you pour your hot water in, take a step back or work close to an open window.
Next part of this series would be about the different stages the item will go through during the felting process and what to look out for.
I hope that you found this post useful! Do let me know if it has worked for you or not by commenting below. Have a great felting day and good luck!