為什麼我的刀會崩口或變鈍，以及如何修復

日本刀崩口與快速變鈍的原因，以及如何在磨刀石上磨掉崩口、恢復刃口。

常見問題

砧板會傷到我的刀嗎？

會。崩口幾乎都來自硬碰硬：骨頭、冷凍食品、陶瓷盤，或是刃口撞到水槽或玻璃砧板。砧板也在這份名單上。一般的合成塑膠砧板對鋒利的日本刀來說太硬，而軟質橡膠砧板對刃口非常溫和，還能延長刃口的保持度。

我們的選品：長谷川抗菌圓形砧板 FKM 系列；長谷川 Pro-PE Lite 黑色抗菌木芯砧板；長谷川木芯 Pro-Soft Lite 橡膠砧板。

什麼時候換砧板也沒用：如果崩口是骨頭或冷凍食品造成的，換砧板不會有任何改變。用粗磨刀石把刃口往下磨，直到整條刃口上的崩口都消失，再依序換回較細的番數。

為什麼我的日本刀會缺角或變鈍，該如何修復？

崩刃幾乎都是因為硬碰硬造成的：骨頭、冷凍食品、陶瓷盤，或是刀刃撞到水槽或玻璃砧板。快速變鈍通常代表正常磨耗，或是研磨角度過大或不一致，且從未徹底拋光。

要修復崩刃，先用粗砥石將刃口磨掉，直到整條刃線的崩口消失，再依序用更細的目數研磨，恢復乾淨且均勻的刃面。這會磨掉一些鋼材，但若置之不理，崩刃只會越來越嚴重。

我們 Knives and Stones 岩刃社的建議：用 400 目砥石進行主要修復，接著用 1000 目以上細磨。使用 Atoma 整平盤保持砥石平整，確保修復後的刃線筆直精準。

根據 Knives & Stones YouTube 頻道

審訂張詹姆斯 · 最後更新 3 June 2026

我的刀以前切得很乾淨，現在切片卻仍然相連。這能修嗎？

可以的。多年研磨在靠近刀跟處磨出的刃口凹陷可能造成這個問題，研磨師可以重新修整刃線，讓整段刃口重新接觸砧板。

檢查時，把刀刃朝下立放在砧板上，後方打光，看看刃口下方是否透光；再從刀跟到刀尖切紙，找出變鈍的一段。刃口變鈍或捲刃的一段，或不平整的砧板，都可能造成同樣的問題。

由 Knives & Stones 撰寫

觀看影片

出自 Knives and Stones 工房

我們自家的磨刀與保養教學——點擊即可播放。

Restoring a badly sharpened Japanese knife: the cause and the fix. You probably seen one before

0:00Introduction: a badly sharpened knife

2:31Potato test before restoration

3:53How to prevent this from happening?

7:02The restoration: reprofiling and thinning

10:19Potato test after restoration

0:00The profile that went the wrong way

A new knife curves up at the tip, and this one curved down. You have probably seen the same thing on a friend's knife, or on your own: the middle of the blade is flat, and the tip has hooked over.

A knife, when it's new, should have a curved up, and this knife is curved down.
—摘自影片

The usual cause is sharpening only the part of the blade you actually use. That section dulls first, so it gets sharpened first, and over time it gets sharpened over and over while the rest of the blade is ignored. The profile goes flat, and then the over-sharpened section starts to hook.

7:20The fix

At this point the knife has lost its chef-knife profile, so the fix is a full reprofile: reshape the blade back to a proper curve, then do a major thinning pass to bring the edge down to the cladding line.

So we are cutting the potato, no longer splitting. And this is the combination of reprofiling, thinning, and sharpening.
—摘自影片

9:11The moment of truth

The whole job took about forty minutes, most of it thinning. A light refinish on 400 grit cleaned up the scratch pattern, then a fresh edge on 1,000 grit. The result: the potato is cut, not split. That is the combination of reprofiling, thinning, and sharpening.