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I realize that subjective opinions about articles, written by those not expert in the field, don't count for much in encyclopediaville; nevertheless I think it worthwhile to record such impressions. In this particular case I do have some nonprofessional knowledge of knives and knife sharpening, and I believe the article advanced my knowledge.
"..abrasive compounds...does not remove any metal"
What a load of nonsense. If you're using abrasive compounds then you are removing metal. Any polishing is removing metal. And even when using a bare leather with no abrasive you're STILL removing metal, just much smaller amounts. — Preceding unsigned comment added by Peanutaxis (talk • contribs) 15:38, 5 August 2014 (UTC)[reply]
The general content related to sharpening ought to be at that article; anything specific to knives could either be a subsection there, or, if a lot of material is available, at this article. --Wtshymanski (talk) 06:34, 29 December 2015 (UTC)[reply]
I endorse a re-write or merger. I slapped a "howto" tag on the article because it seems focused on instructing readers on how to sharpen knives. Felsic2 (talk) 19:24, 3 January 2017 (UTC)[reply]
See this diff. Rotating a blade so light catches the edge, looking for bright spots indicating nicks, or a bright line indicating a dull or rolled edge, is a well-known workshop practice. Here is one page describing such a test. There are many others to be found.
The smallest string is quite visible even though it is too small to be resolved by the camera (and possibly your display device)
The relevant policy is WP:OI. The illustration must not “illustrate or introduce unpublished ideas or arguments”. In this case the microscope does not show an edge approx 0.01 mm wide as there is no scale. The size of the edge in the picture is original research unless a supporting reference is supplied. Further: the claim that “a truly sharp edge is too thin to reflect significant light” is unreferenced. It is also wrong. An object too thin to reflect significant (or enough) light to be photographed is subject to what is known as the ‘guitar string effect’ (so named because the first research paper into the subject used a photograph of a guitar to illustrate the concept).
Basically: if you take a photograph of a standard guitar (accoustic or electric), it has been mathematically proven that the thinnest string is too small to be resolved in the photograph (the original paper was based on photographic film, but the argument applies to digital cameras as well). This takes into account that the overhead lighting required only reflects off about one sixth of the surface of the cylindrical string.
However, photograph a guitar and the thinnest string is clearly visible in the photograph even though it should not be there. It also appears much thicker than it really is if you scale it off. 85.255.233.151 (talk) 13:04, 28 July 2021 (UTC)[reply]
This article is not about guitar strings, but knife sharpening. A guitar's high E string can be .011" or about 0.28 mm in diameter, far fatter than a knife edge dull enough to show a line of light. The guitar string example is irrelevant to the experience of countless workers who use this method to quickly check sharpness of their tools. For them, this needs as much sourcing as "clear skies are generally blue in daytime." For others, I have included a reference to the site of a knife manufacturer in British Columbia. regards, Just plain Bill (talk) 14:06, 28 July 2021 (UTC)[reply]
The principle is highly relevant. But the central issue is that the original research and uncited claims have been removed, so good edit in the end. 85.255.233.151 (talk) 16:29, 28 July 2021 (UTC)[reply]
For a given combination of distances and lenses, you might not be able to resolve a school bus in a photo. For interest, the original microscope image came with software that allowed measurement of small features in the image; this is where 0.01 mm came from. Since the important point is the visible line even under magnification, not the width (which was at best a close order of magnitude since this was at the lower end of the ability of the microscope software to measure), it's probably not important. Anyone actually interested in the physics of sharp knives will not be wasting much time here anyway. --Wtshymanski (talk) 19:11, 28 July 2021 (UTC)[reply]
Wiki Education assignment: Language in Advertising
This article was the subject of a Wiki Education Foundation-supported course assignment, between 22 August 2022 and 16 December 2022. Further details are available on the course page. Student editor(s): Puentesjuan09 (article contribs).