On Wed, 03 Oct 2018 19:39:26 +0100, Wolf K wrote:

On 2018-10-03 14:19, Jimmy Wilkinson Knife wrote:
On Wed, 03 Oct 2018 16:54:01 +0100, Jonathan N. Little
wrote:

Jimmy Wilkinson Knife wrote:
On Tue, 02 Oct 2018 20:27:53 +0100, nospam
wrote:

In article , Jimmy Wilkinson
Knife wrote:

For true grey-scale printing with an ink jet, you need at least two
inks, a black and a grey. Creating grey scale has been a
problemin the
printing trade ever since half tones were invented. Look up duotone
printing.

Most inkjets don't have grey. Using colours won't help to create
greys.

actually, it does.

multiple greys are better, but mixing cmy is an alternative.

Less black makes grey.

Yes, but there are different greys. In graphics there is 'black' and
'rich black'.

The former is 'knockout black' where other colors are masked and only
black ink is deposited, and the later is 'overprint black' where black
is printed over color inks. CYMK 0,0,0,100 vs 100,100,100,100. The same
goes for greys. Using color makes different shades of greys, warm greys
and cool greys.

Except I didn't want any of those, I asked for a non-colour image.

Not possible. Read up on additive and subtractive colours, and colour
perception.

BTW, you know the black wax crayons you used when you were a kid?
They're not actually black, as you can determine for yourself by
streaking a bit of black crayon across the paper, then adding a solvent
to dilute the wax. A truly black wax crayon isn't possible, because it
would have to be basically solid carbon. The colour in wax crayons is
dye, not pigment. A pigment "crayon" is termed a pastel crayon/stick.

Just noticed, if I print from Excel, it only uses black. But if I print something similar from a photo program, it uses colours, even thought the output is identically black. Excel is therefore a lot faster to print.