Needle felting is the process of interlocking wool fibres together, As the needle is repeatedly stabbed in a straight up and down motion the barbs catch the fibres and lock them together. Felting needles are gauged by the thickness and shape of the needle. The lower the needle number the thicker the needle. The higher the needle number the finer the needle.
“Barbs” are cut along the needles shaft. When the needle is poked or pushed into the wool, the barbs pull the fibers down locking them together. “T” or Triangle is the shape of the needles tip, this needle has 3 edges that are flat on the shaft end and in a triangular shape. “S” or Star is the shape of the needle tip, it has 4 edges and a concave groove. It also has more barbs than the triangle and “needles” faster. When needle felting, be sure to keep your fingers out of the way. The points are extremely sharp, trust me on this. :)
Always felt in the straight up/down motion and never bend your needle as they are quite fragile and will break very easy. The main needles most needle felters use are a 38T, 40T and the 38Star , but its always a good idea to try different needles to see what works best for you
You can also use the needles as a single needle or in a multiple needle holder. For flat felting , using a holder with multiple needles will allow you to cover the surface more quickly. For sculpting then a single needle is all thats needed.