Flow Through: You often hear this term but what is it? Essentially its the ability of the brush to release the built up lather from through out the breach onto your face or bowl. Breach: The inner workings of the knot, i.e. the center. Knot: The brush bristles itself bunched together. Tips: Referring to the very top of the bristle. Scritch: The measure of scratch "Scritch" at the tips of the bristle, generally hair grade and density determine "Scritch", for example: Vulfix "Pure" badger lends itself to being very scritchy while Vulfix "Silvertip" badger generally posses none, there are exceptions to everything and vary per manufacturer. Grades of Hair: Each and every manufacturer classifies their own hair, the stigma of pure is pure and silvertip is silvertip, for the most part is false. I can give you a couple of examples; Simpsons "Best" badger in reality is closer to what you expect from other manufactures "Silvertip", Shavemac's "Pure" badger is closely related to what other manufactures would call "Finest" or "2 band". 2 band really is nothing more than an aesthetic, meaning 2 bands of hair are shown above the collar; typically 3 bands are visible. Hair types such as: boar, horse, badger, and synthetic comparisons are highly opinionated and I won't touch on these, your best bet is to just read a review for whatever brush you're looking for, or you can pm me. Density: How tightly packed the brushes bristles are, generally a denser brush holds more of its lather and makes for a scrubbier feeling on your face, a lighter packed brush is known as being floppy since it has less hair packed into the knot. Often the misconception of a floppy brush is that it won't make for a great soap brush, this is not true, in reality it will build lather faster since there is more room for air and water to mix; it may make the initial lather building process harder for some. Floppy: A brush that has less bristles in the knot and that does not contain much backbone to prevent it from falling upon itself. Backbone: Different grades of hair and types of hair offer different types of backbone; generally this term is used to describe the ability of the shafts of hair to withstand pressure and force. Lather Hog: A densely packed brush that doesn't like to release its lather. Water Retention: The ability for the actual bristle themselves to hold onto water; depending on which grade or type of hair you're using, your knot will either hold or repel water. The importance of this can be taken many different ways, boar likes to repel water, meaning more product and water is generally used making for a great initial lather, but may require reloading of the brush to continue with further passes. Badger hair, for the most part is a finer grade of hair which holds onto its water, even if its shaken out or squeezed out... This characteristic makes for a brush that will hold onto its lather and release it more evenly through out the shave, and generally doesn't need to be reloaded. There are exceptions to this as there is in everything. Bloom: After a brushes bristles has been whetted and or used, the bristle opens up like a blooming flower, hence the term "Bloom". Post Bloom: The degree of bloom the bristle displays after being dried. Forms: Much like a mold, this is how hand tied knots are formed, they're pressed into a mold like funnel for shaping purposes. Hand Tied Knot: The process of actually weighing, bunching, tying and forming a bundle of hair and ultimately gluing it together into a knot. Plugs: Machine produced knots gather a bunch of hair, and solidify it into a resin plug. Collar: The portion of the brush where the knot protrudes from the brush, like your head popping out of a shirt collar. Ringlet: Either metal or plastic, used to set the actual knot into before being itself set into a handle; generally used on hollow handles. (See Plisson and Omega for examples) Shelf: A base of material in the interior of the handle, a hardened resin or the actual brush medium itself; the knot is either set into or on top of the shelf. Loft: The actual height of the bristle, measured from above the collar of the brush; generally a taller loft will flow better, and may make the brush floppy, depending on density. Crown: The shape of the top of the loft itself, usually either rounded, i.e. bulb shaped or flat i.e. fan shaped. Fan vs Bulb shaped lofts; generally fan shaped knots were used by the old British establishments and were primarily meant to be used for face lathering since more surface area of bristle would meet with your face. Bulb shaped lofts are versatile and can be used many ways; Plisson is known for their distinct bulb shaped crowns, which work well for the old style of paint brush stroke application of lather. Glue Bump: Excess glue built up in the center of the knot which protrudes past the collar of the handle (See Morris & Forndran as an example). In most cases this doesn't effect the knots performance, however in extreme cases it shortens the essential loft and affects the knots ability to lather (Bestshave "Faux" horse hair brushes for example). Base: The bottom of the brush handle Blank: A solid block of wood, resin, acrylic or other material which is used to fashion the handle from, either on a lathe or CNC machine. Rod Stock: A rod of acrylic, horn, wood or other material shaped as a rod and not a blank. Hand Turned: A term used to describe the fashioning of a brush handle done by hand on a lathe; its often loosely used to describe turning handles on CNC machines. Lathe: A machining tool which spins a medium while the operator cuts, sands, polishes and ultimately shapes a blank or rod into a brush handle. CNC machines are essentially automated lathes, computer operated and used to shape the piece(s) per programed specifications.