The Andis official chart uses just two words to explain when you need which blade: “Use the skip tooth blade before bathing and the finish cut blade after bathing to complete the cut.”
That single sentence is the whole discipline. A #7 skip and a #7F finish leave exactly the same hair length — 1/8 inch, or 3.2 millimeters. The blade number tells you the length; the letter tells you the stage. And the distinction is critical because they do entirely different jobs.
Why tooth spacing matters more than you’d think
A clipper blade works by dragging hair between a stationary bottom blade and a rapidly oscillating top blade. The wider the teeth are spaced apart, the more hair the blade scoops in with each stroke — but also the more likely it is to jam when that hair is tangled, wet, or caked with dirt.
Skip-tooth blades have spaces of roughly 1/8 inch between the teeth. Wide gaps mean the blade feeds hair quickly and doesn’t choke on clots. But coarser spacing also leaves a rougher surface on the remaining coat — the stroke marks are visible as a slightly striped texture.
Finish blades (marked with F or FC) have teeth spaced much more closely, sometimes as tight as 1/16 inch apart. This denser pattern clips finer, leaves a visually smooth surface, and creates a polished final appearance. But that dense feed demands clean hair — a tangled mat or a thick layer of mud will jam a finish blade flat.
Same length of hair left behind. Fundamentally different tool for two different coats.
The workflow: rough-in, then polish
This is why the two exist in pairs:
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Before the bath — the dog arrives with a shedding undercoat, maybe some light tangles, possibly muddy feet. A skip-tooth blade (#7 skip, #5 skip, or #4 skip) tears through it fast, eating the undercoat and opening up the matted zones so water can reach the skin. It’s rough work — the blade doesn’t apologize for the striped texture because the dog is going in the tub next.
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After the bath and dry — the coat is clean, undercoat is blown out, and any remaining tangles are detangled. Now you want the finished look. Switch to the same-length finish blade (#7F, #5F, or #4F) and run it over the body. You get the same length of hair left, but now the surface is smooth and salon-quality.
Both Andis and Oster’s breed charts follow this two-stage approach in their official recommendations. The rough-in card often includes a skip-tooth blade; the finishing detail always specifies F or FC.
The cat safety line: finish only
Here’s where skip-tooth and finish are not interchangeable — on cats, there is no choice.
Andis’s official blade chart carries this explicit warning: “Do not use skip tooth blades on cats.”
The reason is biomechanical. A cat’s skin is thinner and more mobile than a dog’s, and the wider gaps in a skip-tooth blade create micro-suction zones as the blade passes over undulating skin. Those zones can nip or pull the skin into the blade. A finish blade’s denser tooth pattern distributes pressure more evenly and avoids that risk — as long as you keep the skin stretched tight during clipping.
The same caution applies to any close blade (#30, #40) on both species: keep skin taut. But for cats with skip-tooth, the answer is simpler: don’t use it at all.
When you might skip the finish step
In a busy grooming day, some groomers use a skip-tooth blade and accept the striped texture rather than returning for a finish pass. On a puppy cut or a matted rescue where the priority is removal over aesthetics, this is honest work. But if the dog is going to a show ring or a photo session, or if the owner expects a salon finish, skip-tooth alone isn’t enough — the second blade is why the two exist.
Quick reference
| Blade | Tooth spacing | Use when | Result |
|---|---|---|---|
| #7 skip-tooth | Wide gaps | Heavy coat, tangles, pre-bath | Rough texture, opens mats |
| #7F finish | Tight, even teeth | Clean, dry coat, final polish | Smooth, salon-quality surface |
Both leave the same length of hair — 1/8” (3.2 mm). The spacing controls the feel and texture of that length. That’s the whole secret.
For a complete blade-by-blade chart and breed-specific recommendations, visit our clipper blade guide. To find which blade your clipper takes, use the blade & comb finder.