About angles... I am posting some of the different permutation of the poster in CMYK, but before I'll just quote Mark Gatter, in his book "Getting it right in print, Digital pre-press for graphic designers, page 33-34, "Consider the way we see colours. Obviously enough, we see black as the darkest, yellow as the lightest and cyan and magenta fall somewhere in between. When any one of them is printed as a fine screen (around 150 lines per inch), the dots are so small we cannot see them even if we hold the sheet only 205-300 mm away from us. Yellow is even harder to distinguish. It is so invisible to us as a shape that we have not even noticed it causing a moiré pattern in every four-colour print we have ever seen. And yet that is exactly what it does. Yellow can slide in between any two of the other colours, only 15° away from both of them. It always causes a moiré, and we never, ever see it. But it is not the case with any of the other colours.
Printers take things even further. As well as there being a range of relative visibility in the colours themselves, there are more -and less- visible screen angles. Not surprisingly, the most visible orientations -the ones which we will see more easily than any of the others- are 0° and 90°. When you think about it, it makes perfect sense. Our world is filled with vertical and horizontal objects, and so we are especially used to noticing those particular angles.
The least-visible orientation is 45°, and this is where black, the most visible colour, is placed.
To recap, yellow, the least visible colour, goes in at 0° or (or90°), the most visible angle.
Black, the most visible colour, goes in at 45°, the least visible angle.
Magenta and cyan are placed 30° either side of black, one at 15° and the other at 75° -and it does not matter which of them goes where."
This explain why sometimes the black seems to "eat" the other colours in certain permutation, especially when it replaces the cyan or magenta or yellow stencil.
Image from the book of Mark Gatter, page 34
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  Permute' v.t. interchange.—permutation Some close-up.

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The silkscreen studio finally reopened, I printed the last layer of the four-color posters I am working on. I'll post pictures later, for now I am posting the posters I printed in January. The idea was to conceive a picture made of gradients on photoshop, with all the spectrum of color, to decompose the picture in the four layers, Cyan, Magenta, Yellow and Black, to apply half-tones, and then to "play" with the four stencils in silkscreen. If you consider that there are four variants in four color process print (CMYK), if you permute the stencil, still printing with these four colors, you get 15 different posters [arrangement of a number of quantities in every possible order, according to Collins dictionary]. In order to avoid the moiré pattern, printer have achieve to create the perfect combination of angles in the halftones, so Cyan is printed with an angle of 105 degrees, Magenta 75, Yellow 90, and Black 45. So when you overlap them, you get a regular rosette. The picture was compose with very few black, but a lot of yellow, which means that when the black was printed on the yellow stencil the poster was very dark, and the yellow printed on the black stencil, disappearing in the poster, too pale.   ¶ 00:02 0 Comments