The colour of white in printing

[Pyanepsion]

Hello everyone,

I am very intrigued by the default white in the Affinity suite.

Its white has a CMYK component of no ink at all (Cyan 0%, Magenta 0%, Yellow 0%, Black 0%). So why do we get white in a solid white and not transparent?

 

[Old Bruce]

You have made a false assumption about White being simply the absence of inks.

Just now, Pyanepsion said:

why do we get white in a solid white and not transparent?

Why would you get solid yellow and not oh say yellow that is 25% opaque? I mean, after all the other three inks are missing.

[NotMyFault]

2 hours ago, Pyanepsion said:

Its white has a CMYK component of no ink at all (Cyan 0%, Magenta 0%, Yellow 0%, Black 0%). So why do we get white in a solid white and not transparent?

When you create a new document, you can choose if you want a white or transparent background. Its your choice. 

Even after creating documents, you can change the background setting any time.

When exporting, it depends on export file format and settings if transparency is supported or not.

 

[lacerto]

Obsolete.

[Pyanepsion]

I can see from the answers that my question was unclear. I will ask it again in a different way.

 

Colour is obtained in printing by superimposing several monochrome plates.

The plate is not actually uniform. It contains tiny drops of coloured ink evenly spaced from each other. The ideal drop is round and its maximum diameter is defined by the resolution. The diameter of each ink drop varies from 0 (no ink) to 100% (maximum intensity) of the maximum diameter (or, another technique, the points are more frequent).

In current printing, a trichromatic system, Cyan, Magenta, Yellow, was quickly used.

In this universe, black was obtained by saturating the three inks to 100%, but this black tended to be brown. The printers then increasingly added a supporting black to first reinforce the shadows and write the black text of the works in colour, then to finally reinforce all the colours.

Eventually, the four-colour system, as we know, it became Cyan, Magenta, Yellow, and Black.

55 minutes ago, lacerto said:

In a sense [white] has the same effect as the ‘Erase’ blend mode, by not allowing a colour underneath.

We agree, but why does white (CMYK 0 0 0 0) not allow the coloured paper (e.g. cream) to be seen and remain white?

[MikeW]

Cream, if that is the color of the paper, will be seen in your example. 

On the design surface, white simply indicates there will be no ink. Even though it displays as opaque. White will knock out every thing below it.

 

[Pyanepsion]

Thanks MikeW. So the white I saw was a support colour. I am reassured.

[lacerto]

Obsolete.

 

[thomaso]

Additionally to @lacerto's hints:

47 minutes ago, MikeW said:

On the design surface, white simply indicates there will be no ink. Even though it displays as opaque. White will knock out every thing below it.

15 minutes ago, Pyanepsion said:

So the white I saw was a support colour.

Not only. Both "flavours" of white are useful or required, in particular (not only) for screen view. If you create a PNG you might want transparency AND non-transparent white. You could not create the latter if Affinity would handle all no-ink as transparent. Same with PDF, e.g. for web view: if your PDF viewing app can display transparent white then it also displays the two as different – like Affinity does (only) if you have activated its transparent background pattern.

But also for print layout the difference is useful, for instance if you place a logo which contains white on a different colour – and transparency around its e.g. round or star shape. Then in Affinity a white bounding box background would disturb in the print layout if its document is set to show transparency as white (as usual for print layout).

In this examples the Star is set to transparent via blend mode Erase. Affinity layout:

Exported as PNG, opened in Apple's Preview.app …

… and the PNG opened in Acrobat:

Whereas an exported PDF appears confusing to me on screen: the Star does not show transparency, though the blank page around displays Acrobat's transparency pattern / and Preview.app shows no transparency at all:
@MikeW / @lacerto, any idea why this happens with the exported PDF?

[iconoclast]

I think, the point is that in CMYK you have four channels: Cyan, Magenta, Yellow and K for the Keycolor Black. There is no White channel (or a lightness channel like in HSL or HSV), because the printing process is subtractive, means that the colours of the four channels will be printed over each other as rasters and mix up optically to the mix colors, subtracting colors from the spectrum of the reflected light. There is no white except the white of the paper. If the paper is colored, there will be no white anyway.

I don't know how it works if you want to print directly e.g. on black T-Shirts. In that case you would of course need white printing color. That must be a special printing process, not simply using CMYK. Never had to do with it.

Edit: Years ago I saw some printings in a magazine that were printed on dull black paper. The printings were fully colored and very brilliant glossy. That must have been a special printing process with more than four colors too. It was an interesting effect.

[lacerto]

Obsolete.

[Old Bruce]

I think we are confusing colours with inks. Inks do not exist in the computer. We do not see the yellow ink with its inherent transparency. We only see the yellow colour. At 100% opacity.

Overly simplified description follows.

Cyan, Magenta and Yellow Inks are, to a degree, transparent.

On the computer: Put a magenta rectangle over a cyan rectangle. Why don't we see the cyan showing through the transparent magenta? Colours are not Inks.

On Paper: Put a magenta rectangle over a cyan rectangle. We see the cyan showing through the transparent magenta. It will look Blue.

[lacerto]

Obsolete.

[Old Bruce]

The question was 

23 hours ago, Pyanepsion said:

So why do we get white in a solid white and not transparent?

There is no ink nor any paper involved. White is a "colour".

[iconoclast]

I think this discussion is going strange ways. There are good reasons for the CMYK-color-space. "Four-Color-Printing" is the keyword. Because those four colors (Cyan, Magenta, Yellow and Black) are the only colors that will be needed for Four-Color-Printing, there are four channels, one for each of those colors. Because the white will come from the paper, we need no white printing color and no transparency. It doesn't matter if the spaces that are meant to be white are solid white or transparent in the CMYK-document, because there is no white channel, and no white channel is needed. The less color is printed on that certain areas, the whiter they are. So no matter if you call white a "color", a "lightness", "greyscale" or whatever, it doesn't matter, because it doesn't need to be printed.

[R C-R]

2 hours ago, lacerto said:

If we can talk about CMYK colors on a computer display, then we should be able to talk about inks, as well.

But aren't colors & inks two distinctly different things? For example, inks may be available in many different colors & even among the C,M, & Y ones produced by different ink makers may each have slightly different colors.

IOW, color is property of inks & also a property of computer display elements, but just because they each have color properties that does not make them the same things ... right?

[Alfred]

12 hours ago, iconoclast said:

I don't know how it works if you want to print directly e.g. on black T-Shirts. In that case you would of course need white printing color. That must be a special printing process, not simply using CMYK. Never had to do with it.

That’s correct. If you want to print in white on a black T-shirt you can’t use CMYK process colours, you have to use white ink.

I once saw a demonstration of a photocopier that could use a white toner cartridge, allowing white designs to be printed on black paper (or any other dark colour).

[thomaso]

17 minutes ago, Alfred said:

I once saw a demonstration of a photocopier that could use a white toner cartridge, allowing white designs to be printed on black paper (or any other dark colour).

In the late 80ths white toner was common in larger copy shops, it was perfect for mock-ups of white design on brown wrapping paper, trendy at that time. Such a copy not only had a more natural, haptic surface than the high-gloss 4-colour copies that appeared, but was also much cheaper than them. For some reason these machines disappeared with DTP, perhaps because people generally used copy shops less often.

… But it is still available: https://www.ghost-white-toner.com/white-toner-m254-054-w/

[iconoclast]

7 hours ago, Alfred said:

That’s correct. If you want to print in white on a black T-shirt you can’t use CMYK process colours, you have to use white ink.

I once saw a demonstration of a photocopier that could use a white toner cartridge, allowing white designs to be printed on black paper (or any other dark colour).

I remember that I had a project in the 90es. I wanted to order some prints on black T-Shirts. But I couldn't find a print shop that was able to do that for acceptable conditions. Usually such prints were made on a surface that had to be ironed on the shirts afterwards, so that you had a hard plank on your chest if you wore the shirt. Very unsatisfying. So the shirts never got printed. As far as I remember print shops who could print white on black directly were very rare and expensive.

[NotMyFault]

Aren’t spot colors the solution for this?

https://affinity.help/publisher/English.lproj/pages/Clr/spotClr.html

 

[leobrachetto]

Hi guys , I need to print with super white with a laser printer.  Does anyone know this Nevica Xerox system?  the white is phenomenal with 2 layers