Ladies & Gents - Because it is coming up regularly, and pictures are often requested, I decided to make some crude diagrams depicting aspects of the dreaded blade angle.
To start out with, let's define the terms:
That is easy enough. I took a basic Merkur as my model. The following discussion may not hold up for other razor geometries, but the principles should be easily transferable.
Note that the cap is curved more at the top than at the bottom. In other words, the radius is smaller at the top than at the bottom. The edges of the guard lie on the same circle as the top of the cap. The blade itself conforms to the shape of the bottom of the cap. The blades edges seem to lie on the line connecting the cap edge with the guard edge.
How to find the correct blade angle
It is often stated that a good blade angle to start out with is about 30 degrees (relative to the skin). In order to find the corresponding handle orientation, it is recommended to place the top of the razor against the cheek with the handle being perpendicular to the surface of the skin, then lowering the handle until the blade just touches the skin. See the following diagram:
Note that for this razors geometry, that angle can also be obtained by placing the guard against the cheek with the handle pointing to the floor, then raising it until the blade touches the skin. This is because the edges of the guard, the top cap, and the blade all lie roughly on the same line. See the following diagram:
Warning: this approach is only valid if not too much pressure is applied to the skin. If that is the case, depressions are formed, and all bets are off.
The stroke
Now lets examine what happens during a "perfect" stroke. When both the cap and guard edges touch the skin, the blade is also in contact and will cut whiskers very close to the skin.
Obviously, the razor was designed precisely so that the blade edge just touches the skin. If the handle is held such that either only the guard edge or only the cap edge touches the skin, the blade is lifted away from the skin. In this case, the shave wont be very close. Thats why it is so important to figure out the curvature of ones face, so that the handle can be oriented properly. This is very difficult to achieve consistently, so dont despair too much, help is on the way.
How to overcome the difficulties of maintaining proper curvature
Essentially three options are available for the DE shaver (please let me know if there are others):
1. Apply pressure. Using more pressure allows the blade to cut the skin at other angles than those defined by the razor geometry. This method is difficult to master, however, we all use it occasionally, albeit perhaps involuntarily. Often, irritations, nicks or cuts are the result.
2. Use a Slant. Depicting blade-angle aspects for the Slant is an assignment for long winter nights...
3. Use adjustable razors (see following discussion).
The adjustable razor
For adjustable razors, the distance (along the handle axis) between the guard and the blade can be varied. I dont know all adjustables on the market, but I surmise that the geometry of the razor at the lowest setting corresponds to that of a regular, non-adjustable razor as described above. When the distance is increased, there are now two options available for the handle orientation.
Orientation 1: In this orientation, the top cap is in contact with the skin, and the blade angle (with respect to the skin) can vary from about 30 degrees to somewhat larger numbers.
Orientation 2: In this orientation, the guard is in contact with the skin, and the blade angle (with respect to the skin) can vary from large values (about 60 degrees) to about 30 degrees.
The larger angles result in a more aggressive disposition of the blade. Therefore, using the top cap as a guide is safer than using the guard as a guide. However, I am convinced that many gents instinctively place the guard against the skin and then vary the angle, rather than using the top as a guide. I am saying that, because thats what I did until I looked into things, and I dont want to believe that I am the only one making this mistake.
Thus, using an adjustable razor at settings other than the lowest one, will likely result in closer shaves, but also in more irritations and perhaps more nicks and cuts because of the steeper blade angles.
What about the blade being parallel to the skin?
It is sometimes assumed that a parallel orientation of the blade (with respect to the skin) would be optimal. However, no DE or SE razor that I know of actually allows the blade to come close to the skin when it is held parallel.
The top cap will touch the skin first, resulting in a large gap between the skin and the blade. I am afraid, the ideal of a parallel blade is an exclusive of the straight-razor world. I'd be interested to know if there are any DE or SE razors that allow a parallel blade orientation.
Thats the end of my essay for this moment. As usual, if there are any factual errors, please let me know, and I'll correct them as soon as I can. Also, please let me know about any additions.
Best - MM
Very useful illustrations and nice discussion! This will help many!!
