Should I Use My Sharpening Stones Wet or Dry?
Which is better, wet or dry sharpening?
Or, put another way, "Do I need to use water/oil with my sharpening stones?" This is a question that comes up regularly here at Sharpening Supplies. Conventional wisdom says that using water or oil with a sharpening stone is better than sharpening dry because the fluid helps float away the swarf, or waste material, and prevents the stone from clogging. Yet many sharpeners find it tempting to use their stones without going through the time, trouble and mess that comes with water or oil.
Well, conventional wisdom is great, but hands on experience is better. So to better answer the question, some testing was in order to see if wet or dry sharpening really does work better.
We collect all kinds of blades for doing experiments and product testing. Somewhere along the line, an aborted attempt to turn a file into a knife ended up in our collection, and it provided the perfect piece of steel for this test. Steel that could be used freely on a variety of stones without fear of damaging a valuable blade.
Two stones of each type and grit were used for the test. Approximately five hundred strokes of the test blade were taken on each. One stone was used dry, the other was used with water or oil, depending on the type of stone.
Crystolon, India and Arkansas stones were used to sample oil stones. For the test we used Sharpening Supplies honing oil, a highly refined mineral oil. We applied the oil as needed to keep the stone covered while being used. Overall, the oil stones showed the greatest difference between wet and dry use, with the dry being much less efficient. In each case, the stones used dry required cleaning or resurfacing after the test, but the stones used with oil did not.
Coarse Crystolon stones were used for the test. The stone used with oil had no discernible loss of cutting ability throughout the test. However, the stone used dry quickly slowed in its cutting speed and was visibly filled with swarf by the end.
Medium India stones were used for the test. The results were similar to the Crystolon stones. The oiled stone worked consistently throughout the test, while the dry stone slowed substantially. An interesting note in this picture is the poor lapping job visible on the dry stone. Rest assured this was a defective stone that we would not sell, but it was good enough for some rough testing.
Soft Arkansas stones were used for the test. The difference between wet and dry is easily visible in the photo. The dry stone built up heavy swarf, and was cutting very poorly, if at all, by the end. The oiled stone lost no cutting ability throughout the test.
Both continuous surface and interrupted surface diamond stones were used for the test. Water was used as necessary to keep the surface of one stone wet during use. Like the oil stones, diamond stones also showed a significant difference in cutting ability between wet and dry, again with the dry being slower. In all cases, the stones used dry required cleaning to be brought back to working condition after the test, whereas the stones used wet, did not.
Coarse Interrupted Surface
The dry coarse diamond stone shows the build-up that caused a noticeable slowing in cutting speed. As was the case in the oil stones, the stone used wet continued to work well throughout the test.
Fine Interrupted Surface
As with the coarse interrupted surface stone, the build-up of the waste is clearly visible on the fine dry diamond stone. The loss of cutting efficiency was even more pronounced on the fine interrupted surface stone than on the coarse. Consistent with the other stones, the wet stone worked the same from start to finish.
Extra Coarse Continuous Surface
The results with the extra coarse continuous surface diamond stones were consistent with the other diamond stones. As the waste steel left behind is almost the same color as the stone itself, the build-up is harder to see, but again the dry stone lost considerable efficiency, and the wet stone performed the same throughout.
Waterstones of 220 and 4000 grit were tested. As the name suggests, waterstones are meant to be used with water, and water is what was used. The wet stone was soaked prior to testing and water was applied as needed to keep the surface wet throughout use.
220 Grit Waterstone
The 220 grit waterstones had the most interesting results of any of the stones in the test. The difference between wet and dry was not great in terms of cutting speed. The dry stone cut at roughly the same rate as the wet stone. Perhaps this is due to the soft nature of the stone’s binder which breaks down rapidly, constantly exposing fresh grit and resisting clogging. Both stones required similar amounts of resurfacing to be brought back to level after testing.
4000 Grit Waterstone
The 4000 grit waterstones showed even more glazing and loss of cutting ability than most of the other stones in this test exhibited. The build-up visible on the dry stone resulted in little, if any, practical cutting ability well before the end of the test. In contrast, the stone used with water worked the same from beginning to end. The stone used dry required resurfacing after the test, but the wet stone was ready for continued use.
The results were clear. Use your stones wet. The stones used wet worked far better than the ones used dry, the only exception was the 220 grit waterstone which performed the same. In all cases, the wet stones continued to function from start to finish with no loss in cutting ability. In all but one of the cases, the dry stones quickly slowed and some even became useless. In addition, the majority of the stones used dry required more time and effort to clean or resurface afterwards than the stones used wet, most of which could simply be wiped off and put away.
In short, using water or oil with your sharpening is very important. By using water or oil, it just allows your stone to work more effectively and it will save you time.