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July 21

Microplastics detachment

Why, even though plastics degrade slowly, over hundreds to thousands of years, microplastic particles detach from its parent body (often bottles), contaminating the surrounding area, but glass bottles, for example, seemingly don't have such property? 212.180.235.46 (talk) 10:58, 21 July 2024 (UTC)[reply]

Because plastics degrade and glass doesn't. See Polymer degradation. Alansplodge (talk) 11:08, 21 July 2024 (UTC)[reply]

Glass in the sea does degrade too. As it washes up and down on a beach, the surface becomes rough. Graeme Bartlett (talk) 12:20, 22 July 2024 (UTC)[reply]

Also, most glass bottles are made from materials that, when worn down into particles, are virtually identical to natural sands, so do not contaminate the marine environment. See also Sea glass (which I have always known as drift glass). {The poster formerly known as 87.81.230.195} 94.2.67.235 (talk) 00:27, 23 July 2024 (UTC)[reply]

Colors. (The Color Painter)

I'm not sure where to start. This work defines 12 basic colors. Some are named, and I tried to match them up to sRGB equivalents...

However, I'm no expert on colors.

The original is written in the 1880's, and the author was connected with commercial printers in the US.
It seems reasonable to assume the basic colors were originally intended to match up with available basic pigments available at the time of publication.

So what are the likely 12 original colors (ideally based on pigments that would be generally available to a printer in the US) as modern (and sRGB equivlants?)

The page on Wikisource: s:Page:The color printer (1892).djvu/23 , someone on commons tried to tweak the colors in s:File:The color printer (1892) - Basic tones.svg ShakespeareFan00 (talk) 16:15, 21 July 2024 (UTC)[reply]

The author writes, "These colors were adopted because the writer believes that a greater variety of mixed colors can be produced from this selection than from any other containing the same number; besides, these colors are not only the most useful, but also, the most common, and best known among printers." So they were obviously widely available as printing inks, although I doubt they were thought of as "basic" pigments. We have a List of inorganic pigments; I expect most of these 12 are among them. Even if identified, it may not be obvious how to place them in sRGB colour space. --Lambiam 19:23, 21 July 2024 (UTC)[reply]

I wouldn't sadly know where to start looking for information as to common printing inks in the 1880's, but from initial reading around, I'm finding that the articles on pigments don't necessarily have sample colors on them. ShakespeareFan00 (talk) 17:10, 22 July 2024 (UTC)[reply]

You probably know this already, but 'The Printer's Manual: An Illustrated History: Classical and Unusual Texts on Printing from the Seventeenth, Eighteenth, and Nineteenth Centuries' by David Pankow says that Earhart's 12 colors came from "twelve stock inks". Maybe they had the same names that he used...not that that helps you get closer to your objective in any way whatsoever. Sean.hoyland (talk) 17:23, 22 July 2024 (UTC)[reply]

Wasn't there a museum that kept a collection of old pigments / inks? ShakespeareFan00 (talk) 19:46, 24 July 2024 (UTC)[reply]

The Forbes Pigment Collection at the Harvard Art Museums.[1] Their online CAMEO database, of which the Forbes Pigment Database is a section, runs on MediaWiki. DMacks (talk) 23:53, 25 July 2024 (UTC)[reply]

Thanks. So it's a case of working out what the stock inks were. In the scan some of the color samples like Vermillion and Rose Lake seem to be different from what I was finding with those names. And whilst the work says it used zinc white, using an approximation I found for that as an HTML triplet, gave colors that were too desturated compared to whats in the scan. Some degree of pigment fading or color change is not unepexected in a more than 100 year old work, but it would be nice to try and figure out collectively what the originals might have been :) ShakespeareFan00 (talk) 19:45, 24 July 2024 (UTC)[reply]

Vermilion is actually not one specific colour but a colour family. The pigments are very likely still available today – if not as commercial printing inks, then as artists' paints. There is no guarantee, though, that two colours with the same name from different producers are identical. Also, there is no guarantee that the colours you see on your screen are the same as those on the physical pages of the book. The average RGB triple for the scan of the colour labeled BLUE is (63, 125, 161), or #3f7da1 , which is not very blue, more like steel blue , so the scanned B values are perhaps systematically too low. --Lambiam 00:12, 25 July 2024 (UTC)[reply]