Fixing Clogged Whetstones

Sometimes when sharpening you may notice that the whetstone itself is slippery, or perhaps the knife isn't sticking to it so well. This makes sharpening significantly more difficult, if possible at all.

One possibility is that there is grinding debris from the knife or other items stuck in between the abrasive grains on the whetstone that you can't see.

We refer to this as "whetstone clogging", and certain types of whetstone are very susceptible to this. For example, resinoid and magnesia style whetstones, which often fall into the medium to fine category but you'll see some rough ones from time to time also.

Cause of clogging

An artificial whetstone is made by bonding abrasive grains together, and clogging occurs when shavings from sharpening get stuck between those abrasive grains.

When sharpening, it's those protuding abrasive grains that sharpen the protruding knife edges, so if the grains themselves get clogged up, they won't work correctly and cause any knife you're sharpening with to slip - which is unsafe!

Additionally, if you keep sharpening in this state, the heat will cause polishing burn which is bad for both the whetstone and the knife. Be very careful of this, as that's a lose/lose situation.

Dealing with clogging

In short, the more you sharpen, the more debris that will get caught in the whetstone's grains, so there's no way to completely prevent clogging. It's a necessary part of sharpening.

There are methods to prevent buildup though and delay this clogging process. The best one is simply to sprinkle water on the whetstone as you go. This will cause the shavings to be washed away from the surface, and as a result it's less likely for them to be packed into the whetstone and clog it.

Additionally, regular resurfacing of your whetstone will prevent clogging, such as with a levelling stone (resurfacing stone) . Plus that will keep your whetstone flat and ready to use!

If you keep sharpening using a clogged whetstone, sharpening becomes near impossible to do. The knife blade will just slip, which could potentially cause injury. Don't throw this stone away though! Clogging can be removed and your whetstone can be very easily brought back to life.

We do this via a technique called dressing, which brings the surface back out once again. This can be done via one of two methods.

1. Grind together two whetstones with similar grit numbers. Try to get this as close as possible, but we understand if you don't have two whetstones of the same grit number, as that is something only key enthusiasts may have.
2. Use a dressing stone, otherwise called a nagura stone to clean your whetstone. Some whetstones, like our Kirameki Series #6000 and above come with one of these stones included so you can keep your whetstones in peak condition. This is especially important with finer stones, as the grains are smaller and more compacted in.
   
   

It can be best to do these immediately after you've done your sharpening as well, this way you don't forget and it keeps your stone in working order for the next time you need to sharpen. Even if your stone looks fine, there may be clogs that are too small for the human eye to notice, so it's always good to do this just in case.

This makes your whetstones safer to use, and your sharpening experience overall a much better one.