How to Set a Knot in a Shaving Brush
This method will set a badger knot into a resin handle using silicone as the adhesive. That is my personal preference because it is essentially permanent. But with some firm pulling, the knot can be removed for resetting at a different depth or moved to a different handle. Epoxy is not as flexible, and may require the destruction of the handle to remove the knot.
I use standard silicone from a big box store and have had great luck with it for a few years now. Marine grade could be used if you really wanted to.
- Silicone (or Epoxy)
- rubber band
- plastic/nylon washers, 3/8" or 22mm (optional)
- paper towel (for silicone cleanup)
- rubbing alcohol (optional, for an extra clean bonding surface)
- Make the brush knot's base/plug ready... by removing any previous glue or silicone. I've also had a few knots have uneven or slanted bottoms. You may want to flatten that out with a Dremel/rotary tool or file. If you need to do that, I like to cover the hairs of the knot with something to keep the dust out.
Make the handle's socket ready. Similarly, remove old glue here, too. I have never had the need to rough up the bottom surface of the brush before. My knots seem to be holding fine without it.
In a few cases, I have left so old epoxy in the bottom of the socket, when I knew I was going to use spacers to raise the knot anyway. I just made sure the surface was flat and dust free.
- Optional: You may also want to treat the knot's base/plug and the socket with some rubbing alcohol, via a cotton swab, if they don't look very clean. We want a good bonding surface.
- Dry fit by inserting the knot into the handle, making sure it stays in place w/o holding it yourself. If the knot's splay wants to back it out, that will be mitigated when we wrap the knot in a rubber band in the next step.
- Wrap knot in your rubber band. We don't want the splay of the knot to back the knot out of the hole before the glue has a chance to set. I like to be very gentle with the bristles as I do this.
- How deep to set the knot? Use washers to get the right loft. The 3/8" washers I use work well for even 26mm knots, but you can get larger nylon washers if you want. The video includes more discussion about how deep you may want to set your knot. But setting it deeper will give you more backbone and bristle stiffness, and less splay. While a shallow set will let the knot open more and have less backbone. The good news is that by using silicone, you can pull out your knot and reset it if you use too many (or not enough) spacers.
- Look at the angle of the knot. A little tilt, off of center, is often not noticeable if it is a knot that will splay once it's been used, like boars or Silvertip badgers. But you may need to adjust for the tilt by evening out the bottom of the knot's glue plug (which is more likely the problem rather than the handle's socket) if the angle is too severe.
- Get silicone ready. Open the tube and make sure the tip is cut off (like you often have to do with new tubes of silicone). And get that paper towel handy, just in case.
- Silicone in any washers to raise the knot, by putting in about 3-4 small blobs. Press the washer in and give it a 1/4 turn to even out the adhesive.
Review loft. If you still want to look at the loft, then let that dry for several hours and then dry fit again to check everything.
I would remove the rubber band from the knot while you get the spacer situation to your liking. We don't want to bend the bristles any more than we have to.
- Bind the knot with a rubber band to keep the splay from backing the knot out
- Apply enough silicone into the socket to stay mainly at the bottom, to connect the knot base/plug to the handle (or spacer), with barely any silicone at all coming up the sides of the knot base. I often go with 3-4 small blobs.
- Push in the knot all the way. Be firm, but don't use excessive force. Give it maybe a quarter-turn, to spread the glue evenly
- Allow to cure. I like to let my freshly-assembled brushes cure for 3 days. That's probably longer than needed. But 1 day has proven to be too short for me. 2 days might be perfect, but I like to overshoot with this kind of thing.
- All done. When cured, undo the rubber band and enjoy your new brush. And my advice is not to soak your brush in hot water before your shaves. And if you use warm water, I would only soak the bristles and keep the warmth away from expanding and contracting the adhesive.
- I will keep the most current version of my instructions for this here in case new developments arise. Years down the road, if I make an updated video, I'll link to that from that site as well.
- I use nylon washers to avoid any possibility of corrosion, but coins are more readily available. It's possible that American nickels are non-corrosive (research that to be safe), and may be a good option, for US folks, if it is inconvenient for you to find plastic washers.
- One great thing about using silicone to set knots, instead of epoxy, is that you can easily change the loft of your knot if you made a mistake the first time. Just use slow, steady force and the knot should pull right out. Then clean away all the old silicone, add or remove spacers as needed and then glue it back up again.
- Setting your knots with silicone also lets you use handles that are less expensive at first, and then be able to enjoy the brush while you look out for other handles you might like better, like a premium artisan handle, or one with better ergonomics.
- If you don't use enough silicone, and your knot pops out when you're trying to use it. No problem. Just scrape away the dried silicone and do it all over again, using a little more adhesive!