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Question: Is it technically possible to make a 'Black' Whitewash?

True Whitewash is a plaster-like substance that has been used to coat stone and wooden walls for cosmetic and waterproofing purposes since the dark ages. It is made from limestone, and as far as I know it resists all manner of dyes. I do NOT mean the paint. Watch this video to understand what I am referring to.

Conditions:

  • The resulting "blackwash" must serve the same purpose as the original whitewash in that it provides water proofing to as near the same degree as the original whitewash.

  • Pitch and tar, while being black and capable of waterproofing, are not acceptable solutions as they are not as easily applied as whitewash and have undesirable traits (the smell, the adhesive qualities, etc.)

  • As black as possible. The best answer will be that one that meets the previous conditions and has the darkest tint.

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – L.Dutch - Reinstate Monica Apr 24 at 15:32
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    $\begingroup$ Totally unclear what you're trying to do. Just for starters : What are you trying to achieve ? Permanently make what black ? Different materials react different to different substances. What environmental conditions must this withstand ? Note I'm not aware of any dye that would be truly permanent and would not eventually fade or change, so how long is "permanent" really ? $\endgroup$ – StephenG Apr 24 at 15:39
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    $\begingroup$ Whitewash doesn't last that long either. It has to be redone every year or so. So when you say the recipe you have fades over time, what do you mean? Are you looking for a wash (which is temporary) or paint (with is semi-permanent)? $\endgroup$ – Cyn says make Monica whole Apr 24 at 15:52
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    $\begingroup$ You mean paint? $\endgroup$ – John Apr 24 at 16:22
  • $\begingroup$ So, you don't want just a dark-tinted whitewash, you want it black as soot? $\endgroup$ – Alexander Apr 24 at 16:45
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There are some methods of tinting the limewash. 'Naturally' it is done with earth or clay, achieving mostly brownish, yellowish and reddish colors. Modern manufacturers also offer black tint for limewash - https://www.celticsustainables.co.uk/limewash-pigments-black-iron-oxide/. It is said here it is based on black iron oxide and, as you see on the photo there, it gives dark gray, almost black color. Black iron oxide, it seems, can occur naturally and is known as magnetite. https://en.m.wikipedia.org/wiki/Magnetite?wprov=sfla1 So, it seems, if you add crushed magnetite to limewash as you prepare it, you may achieve black color.

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    $\begingroup$ I should repeat again that it would be a dark gray color, not pitch black. Increasing the proportion of iron oxide to darken the color would, most likely, affect the structural integrity of limewash - so not a good idea. $\endgroup$ – Cumehtar Apr 24 at 22:25
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Whitewash was traditionally coloured by mixing it with "earths" (actually metallic oxides)

Copper(II) Oxide (cupric oxide) is black, although producing sufficient quantities without also creating red/orange Copper(I) Oxide (cuprous oxide) may be difficult

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Possibly, but why would you?

Whilst it may be possible to create this “black wash”, it would be made redundant by black paint. At the end of the day, white wash is simply a building material, like cement on bricks.

Think of it this way, if i wanted to make a blue brick house, would it make more sense for me to go out looking for blue clay to make into blue bricks? Or would it make more sense to simply paint the bricks blue when the house was built?

If you really wanted “black wash” though, you could just mix black paint into your white wash and, as if by magic, now you have black wash. You have also wasted a fair bit of paint as most of it you aren’t going to see, so what was the point? It would have been far cheaper to just apply the white wash and then paint it black. By painting it, you also add an additional layer of protection, any weathering would first happen to the paint, then the white wash, before finally the walls.

White wash was often painted in the Medieval period, typically with artwork. I’m not aware of any examples of entire walls being painted black but its not beyond the realm of possibility, it simply was not the fashion.

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  • $\begingroup$ you could just mix black paint into your white wash Not really. You can do this with dyes, but paint uses pigment. Pigments are emulsified, not dissolved. The white component never goes away nor blends in. It's like toner-based printing. The white dots are always present. It takes a lot of volume and black dots to make them "disappear" (by making them ignorable compared to the whole). I've mixed a lot of paint in my life. Getting to pure black when you have white in the mix is almost impossible. $\endgroup$ – JBH Apr 24 at 22:44
  • $\begingroup$ Black suits the theme of my book and fulfils a sense of symbolism. Plus there is no paint in the apocalypse, even if there was, lime is very resistant to dyes, I don't believe paint would work. I realise there is no longer mention of an apocalyptic theme in the description, but the lime itself needs to be black and not be painted on. $\endgroup$ – True Darkness Apr 24 at 22:45
  • $\begingroup$ @JBH True, and i would not recommend using that method in the slightest. As i stated, its far better to just paint it after its on rather than trying to turn it black before. $\endgroup$ – Liam Morris - Reinstate Monica Apr 24 at 22:49
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    $\begingroup$ @TrueDarkness I understand its a cosmetic thing for symbolism to have black walls, but why does the wash itself need to be black? Also, if it was just painted on, you could have a lot more symbolism if thats what you were going for. You could have ideas about harsh facades but you see a different side if you scratch beneath the surface, ideas about the false appearance eroding, or other things like that : ) $\endgroup$ – Liam Morris - Reinstate Monica Apr 24 at 22:56
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    $\begingroup$ @LiamMorris Whitewash was traditionally much cheaper than paint. (As emphasised by the old saying "Too proud to whitewash, to poor to paint") This was because it was far easier to create, from significantly more common materials. So in a poor or technologically deprived area (e.g. post-apocolyptia) paint literally may not be an available option. $\endgroup$ – Chronocidal Apr 25 at 0:26

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