Wet or Dry?
Clipper work is almost always performed best in dry hair. It is my opinion that blending should also be done in dry hair. When the hair is wet, it can be difficult to see lines and hard to tell exactly how the hair is going to lay when cut. The hair should be wet for most shear and razor work.
When performing a haircut, cross-checking is essential. To some, this may seem like an unnecessary step, but it is important to make sure the cut is even and proportional. When doing a short haircut, check for blending and tapering in the mirror (or stand back a few feet). Often, you can see things from a distance that you will miss up close. Also make sure to have proper lighting from all angles. Dim light and shadows make it very hard to check for quality in the cut.
The first step in good blending is avoiding lines of demarcation in the first place. When performing clipper work, go through three steps with each stroke. Start with the clipper anchored with the entire flat surface of the blade touching the head. Moving upward, pivot the clipper so only the heel (back) of the blade is touching. Next, suspend the clipper freehand as it moves up and out of the hair. This will create the smoothest transition possible.
One method of blending between clipper and shear work is to use the clipper-over-comb method. For this technique, use a detachable blade clipper with a large blade (#1 1/2 or higher). The larger blade will give the client a smoother blend because the hair will be cut a uniform length with a feathered end. Never use a short blade or trimmer to blend because the blades will give the hair a very blunt cut and leave lots of small lines of demarcation.
Blending: Blending Shears
Another method of blending is blending-shears-over-comb. Lift the hair up with the comb and use the blending shears to cut the last 1/4" of the hair. When lifting the hair, it is important to slightly overdirect before cutting as this will produce a smoother blend. Remember to only cut the last 1/4’" to 1/8" of hair. Never thin hair close to the scalp as this will create a fuzzy look by causing very short hairs to stick out through the longer hairs. Use a thinning shear with at least 40 teeth. Shears with larger teeth will produce lines. Avoid using regular shears to blend because the blades will give the hair a very blunt cut and leave lots of small lines of demarcation.
Blending: Haircutting Razor
You can also create a blend using a standard straight razor (without a comb attachment). The hair is raked with the razor at a 45 degree angle. The angle of the blade is very important. If the blade is held in a more flattened position, too much hair will be removed. If the blade is held more upright, it will damage the cuticle. This technique was made popular by the Roffler schools and should not be attempted until you have received hands-on training by a barber/stylist who is skilled in the technique. For razor blending, it is essential that the hair be very wet.