Why do the clean Poltava Expert Pro CBN stones leave hairline scratches on the knife blade up from the edge? PDT (Poltava) Expert CBN resin bonded stones set

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Why do the clean Poltava Expert Pro CBN stones leave hairline scratches on the knife blade up from the edge? PDT (Poltava) Expert CBN resin bonded stones set

I lapped my new set of Poltava Expert Pro CBN stones and cleaned them thoroughly after the last use. Stored in a Hapstone box. I just used the set to sharpen a brand new CKF knife at 20 degrees each side. I use soapy water with these stones as recommended by Poltava (and oil on my Hapstone Premium Diamond set). I used the 225 grit stone to set the bevel. When I removed the swarf from the knife it had numerous hairline scratches on the blade face up to 3/8” from the edge. These are quite noticeable to the naked eye. I don’t understand how this happens. What am I doing wrong?

Status: Open Jul 28, 2025 - 07:23 AM

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Answer

Mario Hapstone

Jul 28, 2025 - 07:25 AM

This could be related to several factors — such as abrasive cleanliness, residual swarf, or even properties of the knife’s finish itself. To properly assist, please send us photos and details via email at info@hapstone.pro — we’ll help you troubleshoot step by step.

There are multiple potential causes for these fine scratches, and we’re here to make sure everything works perfectly for you.

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Why do the clean Poltava Expert Pro CBN stones leave hairline scratches on the knife blade up from the edge?

PDT (Poltava) Expert CBN resin bonded stones set

PDT (Poltava) Expert CBN Stone with Organic Bond: for a perfect final polish The PDT (Poltava) Expert CBN Stone with Organic Bond is a high-quality abrasive tool designed for final polishing and refining the cutting edge of knives and other tools. Thanks to the unique properties of CBN and the organ... See More

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Why do the clean Poltava Expert Pro CBN stones leave hairline scratches on the knife blade up from the edge? PDT (Poltava) Expert CBN resin bonded stones set

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