I've been wanting to tie my own brush knots for a while and most of the research I have done has made it seem close to impossible. It seems like it is some ancient art lost to time. There are a couple videos online and some pictorial websites, but nothing showing all the steps. For this project I had to make a few of my own tools, and test out quite a few little tricks, but overall I'm very happy with the end result. 

I decided to start with horse hair, as it seemed the easiest to work with and the most readily available. I got a haft of mane hair in black, and probably have enough left over to make two more brushes.

After being cut to length it goes into a custom hair stacker to get the tips lined up, and then into another homemade stacker with a concave bottom to get the bulb/fan profile. (This step is not so necessary with horse hair because it can be clipped to shape, but will be essential for synthetic and badger hair) The knot is tied here with regular cotton butchers twine in a slip knot. Get it as tight as you possibly can or it will unravel in the next step.

A sharp knife is of the utmost importance for this next step, cutting the hairs down to an even footing.

Now our knot is ready to be glued, before it can be glued into the plug, I use a CA type of glue that is very thin and, wearing gloves, work the CA glue in between all the individual hairs in the knot. I have found this step is the most important to make sure your knot doesn't shed in the future.

Here is the knot with a polyester resin plug that I poured into a 24mm silicone mold that I made for this particular project.

The finished knot, ready to be epoxied into a handle.

I bored the hole in this custom handle down to 28mm to give this knot some much needed backbone and leaving us with about a 65mm loft. Overall I'm very happy with the performance, and was surprised how much lather the horse hair held. 

These are not currently for sale but I do make them in synthetic and in silvertip badger hair at my store.

Thanks for looking!