[quote quote=“wickededge” post=22976]The micro-fine ceramics are very hard. When they come out of the kiln, the grits are sintered and look very flat under magnification. Lapping them with a diamond plate, which is even harder will texture the surface to somewhat resemble the grit size of the diamonds. Because the stone will be lapped in multiple directions, the area of the peaks may be smaller and that will actually increase the space between them, meaning you’ll slightly get smaller, deeper and more widely spaced scratches from the stones than you had before lapping. Lapping with higher grit diamonds will make for a finer texture with smaller peaks. Eventually the peaks will wear off but it takes time.
Here’s a picture of the micro-fine stone at 1200x:
You can see that the particles are very flat so you can imagine how that surface will change as you rub diamonds across it.
*A note on the stones themselves - They are made from aluminum oxide particles that have been sintered at very high heat. The original particles in the micro-fines are in the range of 2.4um-48um for the coarse stones and 1.4um-25.2um for the fine stones. After sintering, the particles are fused and flattened into the form you see in the image above. Calculating the actual grit for these stones is very challenging which is why the manufacturer uses a metric called Roughness Average or RA. They converted their RA numbers to microns for us though it’s not extremely precise and is based mostly on the size of the scratches they leave. We’re in the middle of a project with Los Alamos National Labs to improve our sharpness testing machine design and tighten up our experimental methodology. Part of the project will be examining edges under their SEM. One of the things we’ll be looking at are the scratches from the micro-fines in an attempt to precisely quantify them.[/quote]
Clay: There’s long been talk about how very fine diamond grits cut, as opposed to other types of abrasive media, which do something closer to burnishing. Looking at the photo above, should we infer that this is the case with the micro-fine ceramics? Do they burnish by virtue of their very hard nature?
Can you micro photo the scratch marks of the micro-fine ceramics and compare it to the scratch marks of an equivalent diamond film?
I had seen your blog on this before and was befuddled by what you were seeing for scratch patterns, as they were totally different from mine.
My micro-fines created a polishing effect that seemed perfectly aligned with my diamond films under 5 or 6 microns. Then I lapped my micro-fines on my 1200-grit EZE-Lap plate. I was astounded to see scratch patterns similar to yours.
Did you lap your ceramic stones before the test on your blog?
Tom, that’s weird. No, I hadn’t lapped my micro fine ceramics before I took those photographs. And I never have since. What struck me was that the coarse micro-fines seemed a lot more coarse than the listed 1.4 mu. (Now I know that a mu spec makes not much sense for ceramic stones. Clay explained this well.) Back in the days, when the micro fine ceramics were just out, there were more reports by people with this experience.
What doesn’t surprise me is that after lapping on a 1200-grit plate your scratch pattern is similar to mine (which seems a bit finer than that of a 1000-grit diamond stone). Effectively you maybe somewhat “transfer” the grit size and pattern of the diamond plate to the ceramic stones.
But am I right in concluding that lapping the stones actually made them coarser for you?
Absolutely; lapping the stones on a 1200-grit diamond plate effectively transferred that grit to the micro-fine stones. Both, not just the coarse stones.
Thinking I had maybe wrecked the stones permanently, I tried re-lapping them on diamond film. Surprisingly, they seemed to recover some of their original performance, or something like it. Luckily, Josh had put me onto a less costly film source.
I don’t understand what happened to your micro-fines, but it seems clear to me that they aren’t as advertised. Micro-fines should take a 1000-grit diamond finish and take it to a really nice polish. Ask Clay to send you a new set, or send yours to him for evaluation.
Tom, I’m not sure what you mean exactly. If the micro fines would operate “as advertised”, the coarse stones should have a grit size finer than 10.000 grit water stones. This doesn’t take a 1000 grit edge to a nice polish directly.
I have both the micro fine ceramic stones (1.4 mu / 0.6 mu) and the super fine ones (1200/1600). If I don’t want to use waterstones and want a fine edge, I usually use the progression 1200 -> 1600 -> 0.6 mu. The 0.6 mu stones are (without lapping, and in my case) finer than the 1600 ones.
I think Mark was dead-on regarding the result seen from lapping the ceramic stones with different grits. I lapped mine (1.4/0.6) with my 1200-grit Eze-lap and the scratch patterns I got were very close to what I saw with 1200 grit. I was gobsmacked! I re-lapped one of them with diamond film and the resultant scratch patterns were exactly what I would expect from that diamond film.
Best Sharpening Stones lists 1200 as equivalent to 12 micron. Advanced Abrasives lists 1200 as equivalent to 15 grit. BSS doesn’t list a 1600 equivalent, but AA shows 1600 as equivalent to 12 micron. I use 15 micron diamond film and I think the scratch pattern looks just like my 1200-grit ceramic.
Actually my question was addressed to mark76 but I hope no one feels unwelcome to answer. As indicated by Clay in the quote I posted the 1200/1600 ceramics do not be have the same as the micro fine (1.4/0.6) ones, the latter being dominated by surface finish as you note. I have removed the micro-fines from the next version of my “Grand Logarithmic Grit Chart” for this reason as I deem them too variable. The 1200/1600 ceramics apparently do not keep the surface finish that is applied to them but instead quickly normalize to their own native behavior.
In regards to the original topic, I recently sharpened my ZT 0560 on the Gen III WE. This has an Elmax blade. It originally had a 45 degree inclusive angle, but I wanted to decrease this slightly, so I went to 40 degrees. Started with the 100’s, and worked my way up through the grit progression to 1600 ceramics, then stropped from 5 micron down to .5 micron. The hardest part of the whole process was changing that angle from 45 to 40 and making sure the edge was apexed. It took a little time and a lot of patience, but I got it. I call it a high-polish, as its not quite a mirror finish, but the results are awesome and it cuts very well now. I may add the coarser strops to my collection, as I think that might help take out some of the larger scratches that the finer strops can’t.
[quote quote=“Mr Wizard” post=23984]mark76, following from this perspective:
The 1200/1600 ceramics should have a native equivalent grit size independent from surface finish. Have you attempted to quantify it?[/quote]
Yes, sort of. They behave like finer stones than the 1K diamonds. 1200 / 1600 comes quite close to where I use them in a progression :cheer: . My quickest progression to a mirror edge is diamonds → 1200 → 1600 → 5K Chosera’s → 10K Chosera’s.
If I want to throw something extra in, it’s sometimes the micro-fine stones. Then my progression is diamonds → micro fine coarse → 1200 → 1600 → micro-fine fine → Chosera’s. I also wrote about this on my blog.
I sometimes throw in the 2K / 3K Chosera’s as well, but to be honest, I think that’s overkill. I think these are similar to the 1200 / 1600 stones (as far as scratch removal goes; they work and feel quite differently, of course).
You should note I have the “original” 1200/1600 stones. I’m not sure, but I think Clay switched from manufacturer once for these stones. I don’t know whether the " new" ones work exactly like the old ones.
Why do you feel the micro-fines are variable, Mr Wizard? You can texturize them differently, of course, but this is the case with any hard ceramic stone, like the Spyderco ones. And did you follow the discussions I had with Ken and Tom on the effect of flattening waterstones with diamond plates?
Thank you for your summary. I was not aware that a different OEM was used for the 1200/1600 ceramics at one time; I’ll try to keep that in mind.
As noted in the README I chose to limit my chart to media with quantifiable particle sizes rather than apparent effect (i.e. surface roughness parameters). For the time being I make an exception for the Spyderco ceramics due both to their wide use and presence on other grit charts.
The fact that the “grit” can be changed entirely by resurfacing introduces an inherent ambiguity, as one cannot be sure how the surface has been previously modified or worn. While waterstones are somewhat dependent on surface finish they will normalize to the native grit of the stone fairly quickly due to the expected breakdown of the binder.
Lastly your own report of the “1.4 micron” micro-fine acting much coarser than this rating suggests possible inconsistency in the finish applied to it.