The Shechita Knife

Everything else in shechita is the shochet — his training, his hands, his attention. The knife is the only tool, and the kosher status of the meat hangs entirely on its edge.

That is why the laws of the knife run longer than the laws of the cut.

What the knife must be

By the letter of the Gemara's law, shechita may be performed with anything detached from the ground, provided the edge is sharp and has no nick. The law is wide — flint, glass, even a reed would qualify.

Practice narrowed it considerably. The custom long ago became to use only a metal knife, and:

• with a single cutting edge, not two;
• whose tip does not come to a sharp point;
• whose blade does not stand apart from the handle in a way that creates what looks like a nick at the joint.

That last one is a detail worth pausing on: the concern is not only an actual nick but a junction that behaves like one.

Any nick at all

This is the governing rule and it has no threshold. A pegimah — a nick — of any size whatsoever disqualifies the knife.

And it cannot be worked around. A shochet who knows where the nick is may not simply avoid that part of the blade: the rule is about the knife, not about which portion of it touches the animal.

Borderline edges — a blade that is not quite nicked, not quite smooth — have their own treatment, which is precisely the case the training is meant to equip someone to judge.

Checked before and after. Every time.

The knife is inspected before every use and after every use, and between animals.

The after-check is the one that reveals the logic. If a nick is found afterwards, the question becomes when it appeared — and if it may have been there during the cut, the shechita is in doubt. Checking after is what makes checking before meaningful.

The inspection itself is the well-known twelvefold examination: the blade is drawn across the flesh of the finger and the nail, on both sides of the edge and along the edge itself, so that a nick too small to see is caught by touch.

The closing laws of the siman deal with exactly the awkward case — a nick discovered later, and whether the circumstances give it an alibi or not.

Why this is the heart of it

A nicked blade does not cut cleanly. It tears, and tearing is one of the five failures that invalidate shechita. So the knife requirement is not a separate stringency layered on top — it is what makes the required kind of cut physically possible.

Which is also why one of the three things a rav tests before certifying a shochet is whether he can feel the tiniest nick with his fingers.

See also what shechita involves.