If The Brush: Basic Information Everyone Should Know is a 101 level class, this is a 102 level class. This is going to be a cross between a lecture and a ramble, since I did more of a 'stream of consciousness' rather than an organized outline format. This is also an opinion piece, specifically, mine. There's lots of threads and posts out there that will show you how to glue a knot into a shave brush. Some of them discuss size, depth, etc. What I haven't really seen is a thread that talks about why those things matter beyond someone's personal preference for a stiffer or floppier brush knot. What are some reasons to 'build' your own brush? First, you have more creative control over the finished product, and second, it's often cheaper. The third and most important reason is that you can tailor the brush to fit your particular needs, rather than buying a generic one-size-fits-all brush. Boar Brushes. Boar users, you don't need this thread, there is the door, see yourselves out. ... Still here, huh? Alright. Boars are more forgiving than badger. Want a stiffer brush? Soak it less. Want a floppier brush? Soak it longer. The more you use it, the softer it gets. There's a cult of Semogue and a cult of Omega. Some people are members of both. Moving on. (We'll come back to you later in this post). Badger Brushes. Brush Sizes. I might be alone in this, but I subscribe to "the brush should fit the face" belief. Any good badger knot over 20mm will hold enough lather for three passes. Lather holding capacity usually isn't a huge factor when wetshavers are shopping for a new brush, their eyes gleaming in the reflected light of their phone screen. A 22 to 24mm knot (size measured at top of handle) is an ideal size for most people. It doesn't waste lather and isn't too small or too large. 14 to 18mm is what I would consider too small for comfortable daily use, but small enough to dry reasonably quickly. In short, an ideal travel size. 28 to 30mm You just want to bury your face in that pillowy white cloud, don't you? Suitable for lather wasters, six pass shavers, and big boned individuals. 30mm monsters have earned the nickname "Soap Destroyers." There is also 32 to 40mm. A shaving party? A Hutt? A medium dog? No, my friends. These are primarily leg shaving brushes or head and face brushes. Anyone else just needs an outsized brush to match their outsized personality. Or they are a collector... or both. I seemed to have skipped 20mm and 26mm. Those two sizes fall into the in-between place. 20mm isn't too small... but bigger is better. 26mm isn't too big, but it's getting there. From what I've seen, the majority of wetshavers use a 24mm brush as their daily driver. If the wet shaver is a member of one or more shaving forums, add a +/- 6mm 'hobby' variable for the majority. Just because a person likes a certain type of badger in a certain size, it is no guarantee that the same preference will transfer over to other badger types either. He or she might prefer a 24mm in two-band, but prefer a 27mm brush in silvertip. Or a 28 in synthetic. Sizing a Knot. Just to make things confusing, the size of a brush knot is measured two completely different ways. All of the sizes above are measured in millimeters at the top of the brush handle. If the knot is by itself, and not yet inserted into a handle, it is measured across the base of the knot. The difference between the two sizes is 1mm to 1.5mm. Some vendors list both sizes, most just list the knot size, and expect you to figure out the handle opening size on your own. Price (Why it costs what it costs). You may have noticed that while most badger knots look more or less identical to the novice wet shaver, the price varies widely, as does the hair quality. Quality depends on the weather, especially the weather right before harvesting the pelt. Exceptionally cold winters, warm winters, early spring thaws, all of these changes in temperature have an effect on badger pelts, be it positive or negative. About once every ten to twenty years, you'll get an exceptional harvesting season. It is this type of year that gives birth to terms like High Mountain White and Manchurian. It's kind of like wine. Some years are better than others. Once the hair is harvested, it is graded according to weight, length, type, color and probably a few other criteria as well. The grade determines the price of the hair. The size of the knot has a huge impact as well. The amount of hair going into the knot rises up exponentially, not sequenced nicely in 2mm gaps. A 2mm difference in size might double the amount of hair used in the knot. That is not an exaggeration. Knots are not difficult to make. They are difficult to make perfectly. Photos don't really show it, since all the hairs make a 'can't see the tree for the forest' type situation. You see, knots are trimmed after they are made. All knots. Usually for the higher grades of hair, trimming involves a few longer hairs, perhaps some discreet shading. Few manufacturers produce "perfectly" symmetrical knots. On some Chinese knots you can see flat spots where the person trimming took off too much hair, or the knot wasn't perfectly centered when it was being shaped, and will have a distinct lopsided look to it. Added quality control checks, more time spent with each knot, and extra training is the best response to this sort of thing. Each of those adds costs. I'm not saying that Chinese knots are bad. They can be, but most aren't. This is why choosing your knot from a reputable vendor is important, and often why it's best to go through a middleman like Golden Nib, Ace shaving, etc. Especially if the price seems too good to be true. I once purchased a Chinese so-called, "High Mountain" knot many years ago. Many of the hairs in the knot were so wispy they tangled with normal use. It was exactly the opposite of what one would expect from a high mountain knot. I'm not going to name the vendor. He is well respected in the shaving community and my bad knot experience through him was a one-off random fluke. He offered to exchange it and I declined, preferring to keep the worst badger knot I've ever used as an object lesson. The Glue Bump. When a knot is made, the hair is placed in a cannon (mold) to shape the knot. It is then tightly tied to hold the shape, and then dipped in glue. Capillary action draws the glue up into the base of the hairs and forms what we call 'the glue bump.' Usually the loft is measured from the top of the handle to the tips of the knot. However, if the knot is set shallowly, or if the glue bump is very pronounced, the loft may be measured from the top of the glue bump rather than from the top of the handle. Manufacturers are close mouthed when it comes to guarding the secrets of their art, yet a few details have emerged that give us some insight into the brushmaker's craft. Certain knots and brushes have a 'reputation.' For instance, Simpson's Duke brush is a favorite with face latherers. A glance at the description will probably tell you the knot size, loft, and overall height. Maybe a brief blurb about the three different sizes. What it won't say, is that the Duke, compared to Simpson's other brushes, contains 30% more hair (by weight). Simpson's chubbies are similarly overstuffed. Simpson's own website is curiously silent on this detail. It is safe to say that knot densities have changed over the years. Vintage knots, especially in the higher grades of badger hair, have better hair than today's knots. There are a variety of reasons for that, and the main one, in my opinion, is that the people sorting the hair now are not as good at their job as the people who used to do it fifty years ago. They were also, for the most part, less densely packed than modern knots. This means that most vintage knots have less backbone than modern knots. What does that mean for lather production? The less dense a knot is, the better it will be at making lather. The hairs can move more, which generates lather quicker, and less dense knots also release lather better. You may hear the words "lather hog" as you read these forums. Dense knots tend to be lather hogs. They will make the lather, but keep it trapped unless you really mash the brush. This is good if you are using a stiff exfoliating brush like Best or Two-Band, less good if you are using a silvertip. It's always a tradeoff. Backbone vs flowthrough. The more of one, the less of the other. There are tricks we can use to get around some of the limitations. Opening the handle hole wider. Going up to a half millimeter past the manufacturer/retailer recommendation will decrease a knot's backbone, and aids in flowthrough. A smaller handle opening. Reducing the size of the opening forces the hairs tighter together, this increases backbone and decreases flowthrough. Set the knot deeper. Setting the knot deeper adds backbone. It also helps the brush retain lather. Set the knot deeper and widen the hole. This gives good backbone and has good flowthrough characteristics. You do get diminishing returns the deeper and wider you go. The risk of rotting out the center of your brush from trapped moisture also goes up the deeper you set the knot. There is also the silhouette of the brush to consider. And proportion. Avant Garde brushes are not the norm. Wet shavers, by and large, tend to be a conservative bunch, and most brush handles feature curves and some variation of an hourglass shape. Traditional ivory white, cream, tortoiseshell, horn, and butterscotch handles have given way to a riot of color, patterns and designs. This is a direct result of the (fountain) pen turning hobby overlapping with wet shaving. Depth of the knot. For badger, the starting point should always be 2:1. The diameter of the knot plug x 2 = ideal loft. Ideal loft. Hmpf. Perhaps I should say 'generic' loft. If you order a brush fully built (assembled and glued together), assume a 2:1 loft unless seller indicates otherwise. When ordering knots from Chinese manufacturers, it can be a bit of a crapshoot. It is possible to order custom knots, made to exact specifications. It is also possible that the manufacturer might actually make them to those specifications. I've read a few stories about blokes who have ordered knots based on an initial good sample, and gotten garbage in the main order. It is simpler to let someone else sort though it all, which is why retailers like The Golden Nib exist. He will buy, say, 500 knots. Of those, maybe 20-50 will be discarded. Another 20-50 will be of exceptional quality, and get listed as a higher grade/subset. The Right Tool For the Job. Your lather makers work better with some things than others. Silvertips are superb with shaving creams and soft Italian soaps. You'll want to reach for a boar, best, or two-band brush when it comes to triple and quadruple milled soaps. That's not to say that you can't use a silvertip on a hard soap. You can also use an adjustable wrench to drive in a nail. It will do it, but it's not a hammer. If you are one of those people who happen to be unburdened by little things like deadlines, or who have ample time to shave, or who make time on the weekends. In other words, the rich, the retirees, and the shaving enthusiast... You can afford to use whatever you want. Fun fact: Humans are the only creatures on the planet who will spend 30 minutes selecting the proper tools for a 5 minute shave. You already knew that? Oh... moving on. How not to @$!# up your brush. 9 out of 10 brush manufacturers will say (or words to this effect), "do not use circular motions to load the brush on the soap. Doing so will void the warranty. The tenth one just won't say anything. Is this a valid concern? Kind of. Repeated circular motions in the same direction can eventually cause a brush knot to permanently deform. Sometimes it's called a 'swirled knot.' It's easily preventable, but not easily fixed. If you usually go in a stirring clockwise motion, stir counter clockwise every so often and throw in a few sideways paintbrush strokes too. Some knots have a distinct pompadour and swish to one side. It's not something we see much anymore since most wet shavers don't use shave mugs, and those that do, usually don't leave the brush in the mug when they are done with it. Since I'm on the topic, there is also the 'mashed brush.' All the hairs splay outward from the center, leaving a hole down the center of the knot. This is caused by consistently pressing too hard when you load or use the brush. The knot is pretty much destroyed at that point. Not many people use horse hair brushes anymore. It's a niche segment of the wetshaving world, and I'm not even sure if a person can order just the knots. Horsehair is soft and fine, and you should never swirl or stir with a horsehair brush. Paintbrush strokes only. The hairs have a tendency to tangle if this advice is not followed. Modern horsehair brushes are not as susceptible to tangling as the older ones, due to manufacturers setting the knots more deeply, and making the knots like badger and boar, rather than the traditional ring of horse hair around an open center. Post shave care. Always rinse your brush. Cup it in your hand upright, with your fingers loosely wrapped around the knot, holding the handle with your pinky against your palm. Hold it under the flow of water from the faucet. Squeeze. Relax. Squeeze. Relax. Repeat until no more suds come out of the knot. Give the knot a last firm squeeze. It is now rinsed. Grab a towel, and do several paintbrush strokes on the towel, rotate the brush 90° and repeat. Finish up by wrapping a fold of the towel around the knot and giving it a good squeeze. Set it upright or hanging down from a brush stand to finish drying. It will probably feel slightly damp at this point. The ideal brush drying position, according to a German study, is horizontal, tilted slightly downwards, touching nothing. You don't see many brush stands like that. That's all I have. Hope you enjoyed it. I'll contribute more to this post if I think of something to add. Edit: I do have more to add for boar users, but that will have to wait for another day.