Felting needles come in a variety of shapes and sizes. They are used primarily
in industrial machines that hold thousands of needles in large flat plates to create non-woven fabrics. But fiber artists use them for 2- and 3-D work, either singly or in a hand held apparatus that may hold several needles. I prefer to use only one needle when I am sculpting
figures.
All felting needles have a basic shape. They have a long shank with a narrow shaft that has a very sharp tip.
The shaft may be triangular, star shaped or conical. The thin shaft is barbed. A barb is an indentation, and it is this feature that catches the wool and enables you to felt. The number of barbs, the location, and the depth varies between needles.
The smaller barb depth will push less wool and vice
versa. Lets look at these features and how they affect needle felting.
A thin shaft of 38 or 40 gauge, that is either star shaped or triangular will leave the least visible hole in the finished piece.
On most needles fiber artists are using today, the barbs start 3/8 (9.5mm) from the tip. I suggest using a needle with a barb starting only 3.2mm from the tip.
This needle does not have to penetrate very deeply to work effectively. This is especially good for fine details such as making fingers, toes, and eyes and lips on figurative sculptures, or adding finishing details to two dimensional work. Very little surface deformation occurs as the needle does not have to go deep to push
wool. 
A shaft that has barbs starting at 3.2mm from the tip and with barb depths progressively deeper along the shaft from the tip will allow for very fine and shallow surface work, but also deep sculpting as the needle is pushed deeper into the wool. For instance, when covering a sculpted base with an outer fiber, the needle only needs to penetrate to the depth of the first barb to connect the two surfaces and harden the top surface. Further contouring is done only when desired by pushing the needle deeper to grab more
wool.
There are four needle styles that I use most, and they are available
in a variety pack that I sell on my Felters' Supplies
page. They are:
1) 36 gauge triangle blade with barbs of equal depth starting 3/8 from tip for rough work, deep penetration, or coarse
wools.
2) 38 gauge triangle blade with barbs of varied depths starting 3.2mm from tip for deep or fine work a good general purpose
needle.
3) 38 gauge star blade with barbs of varied depth starting 3.2mm from tip for fast felting and deep or fine work a bit faster than the 38 gauge
triangle.
4) 40 gauge triangle blade with barbs of varied depths starting 3.2mm from tip for fine detail work and fine
wools.
Numbers 1, 2, and 3 are multi-purpose needles.
Numbers 3 and 4 can be used to repair nuno felt.
