Strontium aluminate (glow in the dark) as stropping compound

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Jun 20, 2006
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Strontium aluminate is around 85 on the mohs scale, I am considering using it as a stropping compound to sharpen knives. Why? Novelty factor. Decently hard. Cheaper than CBN or diamond paste.
But the real reason is that using a very bright glow powder would be really easy to see what kind of scratch pattern you're getting and it might reveal other edge issues or at least give you an idea of what your stropping is hitting- high spots on the edge for example.
Before the toxicity issues comes up, this is some of the same stuff put into Halloween glow makeup and while I wouldn't butter my bread with it, you'd be able to see when it's all washed off.
I contacted a manufacturer to verify how hard the crystals are and I also checked into the geometry of the crystals a bit and they seem to have a lot of facets which is -from my novice understanding- a good thing.
Has anyone ever tried using this stuff before? There isn't much utilitarian value beyond what I've mentioned, but I'm sure we could imagine some scenario beyond what I have mentioned where a glowing edge might be useful- trailblazing when tracking a downed deer, and of course alerting you to the presence of nearby orcs on your way to Mt. Doom for starters.
 
would you be able to take a video of this? I'd love to see the glow-in-the dark scratch pattern!
 
Agreed. I thought it would be interesting though to see what we can't see with the naked eye. Like even when flushing and wiing, are you sure that there aren't scratches deep enough that some of your material is still there?
In the same way, I'd like to know where my stropping compound ends up as far as on my work area, sharpening equipment and such to get an idea of where the compound is going - like are we contaminating subsequent strops after we think we have washed off the compound?
Finally, at 85 it's decently hard stuff. My father is a retired attorney so I can get some patent stuff done without legal costs and figured why not give it a shot? There's a few other patents regarding combining with powdered steels that may very well produce steels that can glow- without getting into a lengthy discussion of the science behind it, the crystalline structure of the carbides mixed with a few different versions of this material doped with Europium and other elements that might do some interesting things with how the vanadium carbides will behave, all looking pretty interesting.
I happen to be blessed with a job as a public school teacher for 20 years in the premier public technical school in the whole country (Passaic County Technical Institute) that has a student body of over 5000 and literally 2 dozen specific "shops" (kind of like a major in a college only this is high school) that could handle every aspect of production from conception to milling. Of course, we couldn't make weapons, but this is a labor of love- an opportunity for my kids to get some real world experience in bringing an idea to a reality.
I hate to admit it, but once I have my bills paid and my family taken care of with just enough money to go on vacation once a year and enough to our modest lifestyle going I really don't care about money.
To bring together all the different training shops for our students on a project like this is my dream.
We've already had food from our culinary shops sent into space with NASA to the ISS, and students in our graphic arts and design programs create content adopted by various corporations and federal agencies.

With this in mind, if any like-minded people would like to contribute their time or ideas to model for the world what good old fashioned American ingenuity is about, feel free to email me frank@santora.com
Please understand that while some monetary incentives would naturally be a part of what we do, don't ask to be a part of this because of this reason- in the best case scenario this is going to be about giving back and education, not lining anyone's pockets.
 
Got a few chemists to play along with me. Unfortunately one of my physicist friends went bonkers and is now sitting in the clink last I heard (I think he just meant to put a scare into his stepson, but the authorities didn't take it so lightly)- so if any of you have a background in this let me know if you can help. There's a guy here that does micrographs of steels, I need to use the search engine to find him and see if he has any thoughts on this- if anyone knows who I am talking about drop me a line. Really great stuff from this guy- I mean REALLY excellent science and self-funded from what I remember. He should be getting some more support, going just by anecdotal experience makes progress a slllllloooowww process.
 
Curiosity has me watching what will develop here. The one thing that's still making me scratch my head(?) is the reference to '85 on the Mohs scale' for hardness. Wondering where that came from, in what context?

Mohs scale, by definition, is from 1 to 10, with diamond always being '10' at the hardest extreme. And within those limits, the values assigned (from 1 thru 10) are only an ordinal (ranked) comparison of literally any one material to another, and not an actual measurement. So I'm wondering what the real-world measurement of hardness is, for this particular material. A measurement on the Knoop or Vickers scale would be more indicative, especially as directly compared to values for other known abrasives, like aluminum oxide (Knoop ~ 2100, usually ranked Mohs 8 - 9), or silicon carbide (Knoop ~ 2600, usually ranked Mohs 9 - 9.5 or so). For reference, diamond is usually listed as 7000 on most Knoop scales, as the hardest standard to which all other materials are compared.

Any Mohs chart can list literally any variety of materials on it, each ranked somewhere within the 1 to 10 limits, with '1' usually being assigned to Talc (softest of all known) and '10' being diamond (hardest known), with 2 thru 9 being literally anything else, randomly chosen for the comparison. And by the Mohs standard, 'hardness' is only defined as the ability of the 'harder' materials to visibly scratch the 'softer' materials listed in the same chart. So, an assigned Mohs value for a material only has some meaning when it's known exactly what it's being compared to in that same particular chart. And even then, it only indicates it's harder than materials listed lower, and softer than those listed above it, but still with no absolute measured value of hardness.

If the '85' is by chance a reference to Rockwell (C) hardness, then that scale only really has meaning into the mid/high 60s, after which the equipment used to measure to that standard can't accurately gauge hardness anyway. So again, I'm wondering in what context the '85' value for hardness originated.

One Mohs chart shown within a Wiki article (link below) adds a column for 'absolute hardness' (measured by sclerometer) as compared to the ranked Mohs values. Talc is shown as '1' absolute, and diamond being assigned '1500' in comparison. Implication being, in real-world terms, diamond is 1500X as hard as talc. On that particular chart, an '85' would fall somewhere between Orthoclase Feldspar ('72' absolute) and Quartz ('100' absolute), referencing only the materials listed in that particular chart. That sort of agrees with one reference I'd seen elsewhere, describing the hardness of Strontium Aluminate as similar to that of silica (of which quartz is almost entirely composed). If it's similar to silica, it may be limited in terms of it's usefulness as a stropping compound on cutlery steels. Compare to the limitations of natural stones (Arkansas) for such purposes, as their 'novaculite' mineral crystals are essentially silica-based. Silica-based abrasives really are only effective on steels with little or no hard carbide content (like 1095, low-alloy stainless like 420HC, etc.).

https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
 
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Sorry YES KNOOP, not Mohs.

Take into account that it is doped with europium, the crystal structure is multi-faceted, and the possibility of either manufacturing or combining it with other materials ....
Combined with steels... as part of a DLC... most of these would be novelty applications, but it's an interesting compound and worth looking into.
 
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