Okay, so there has been a lot of questions about the PC Woodcraft and Pen's horsehair knots and as I happen to have ordered one and had everything mostly ready, figured I should do a short show-and-tell about it!
First on the left, is the knot being mounted into handle that hig789 sold and kindly helped a forstner-bitless me enlarge the hole from 21mm to 24mm (thanks again for the help!) to receive the 23.5mm horsehair knot. The top of the handle has several stable cracks, but nothing to be concerned over - just adds some character to the vintage handle. As you can see, I have the ubiquitous blue painters tape ring around the top in little torn bits to help make it easier to go around the hole.
The brush is protected in a 'customized recycled knot shield' (i.e. a fast food receipt from lunch that day) to help protect from any oopsies during the gluing process and to help give it a good shimmy to help seat it, too. As I tend to like flop in my brushes, I set the knot as high as I could, just skirting the glue ring of the knot right below the lip of the handle. You can see where a bit of it is exposed as there was some stray glue on the knot from the knotmaking process.
The image on the right is and 'unbloomed' image of it just after the glue set. The knot seems somewhere in-between a bulb and fan shape at this stage. I was at first worried that there'd be a gap between the knot and the sidewalls of the handle as it was slightly smaller, but with a bit of judicious gluing (and as much fiddling and centering that a 5-min setup time would allow), I seemed to have centered the knot properly.
The above image is post first cleaning and first use, both of which were done with good ol' VdH puck that I break out for this occasion as it tends to be good for defunkification. The first cleaning produced some of yellow discoloration in the lather, as well as did the first pre-soaking. I assume it's from the processing of the brushes, but it easily washed out and did not affect the actual first use of the brush. A shorter soaking didn't produce any discoloration, but will keep track of it to see if it continues.
In use, the brush, even set at the highest loft, still has a lot of backbone and can easily cut into hard soaps. Tips were soft without any scritchyness that I feel in my boar brush even over the course of face-lathering which I'm not at all use to. And, it bloomed very nicely like a badger brush does, too - although like my other horsehair brush, in more of a 'crazy scientist' bloom vs a more coiffed 'Angela Davis' bloom.
After 2.5 uses (1 bowl lather, .5 attempt at hand lathering, and 1 face lather), it still smells of wet animal fur.. which... it is, but it's not overpowering and is quickly diminishing.
I'm very happy with how the PC horsehair knot is performing. I will update the posting as I use it more. Loved the way this turned out and looking forward to another restore sometime soon!