Could be worth a thread. I’ve been wondering how paint colouring systems work, and how house paint colours appear differently to red-green colourblind people. Obviously they don’t mix primary colours.

One company markets a system of 14 different colourants to be added to a base. The base is white or coloured but does not contain any colourants. But what are they (chemical formula and spectrum) and how does a computer decide what combination to pick?

Another website says that 66% of colourants are azo dyes, 15% are
anthraquinone dyes. Copper phthalocyanines, used for their brilliant blue and green colours, account for 2%. But those categories and percentages apply to textile dying, not paint.

The official list of colourants is maintained by the “society of dyers and colourists” in their book “Colour Index International” and all colourants get a generic name such as C.I. Acid Blue 52, C.I. Direct Red 122, C.I. Pigment Yellow 176 and C.I. Solvent Black 34.

The official chart of C.I. hues is this one, which is somewhat different to the names I’m used to. Too many possibilities, though, and I doubt if spectra are available. So where to from here?

There was a regular on the SSSF forum who was all over this stuff. Postholedigger in paint. A Lurking Chemist?

There is a book “handbook of US colourants” that’s in the uni library.

But I’ve already found out that there are about 250 colourants in common use in household products (such as cleaners and cosmetics).

Canon printers use
C.I. direct violet 107 (double azo class) and C.I. direct yellow 173.

As an artists, I have a habit using more than one brush at a time,
often holding one between my teeth whilst working with another,
can’t tell you how many times I stuck the wet end in my mouth.

…that and using my mouth to draw the bristles to a finer point…

It was one of my art teachers that made me aware of the danger
present due to the chemicals.. often minerals.. used as pigments.

Ogmog said:

As an artists, I have a habit using more than one brush at a time,
often holding one between my teeth whilst working with another,
can’t tell you how many times I stuck the wet end in my mouth.

…that and using my mouth to draw the bristles to a finer point…

Yep :(

Ogmog said:

As an artists, I have a habit using more than one brush at a time,
often holding one between my teeth whilst working with another,
can’t tell you how many times I stuck the wet end in my mouth.

…that and using my mouth to draw the bristles to a finer point…

It was one of my art teachers that made me aware of the danger
present due to the chemicals.. often minerals.. used as pigments.

Thanks, searching for pigments rather than colourants cuts down the search immensely, from about 250 in common use to about 50.

The nomenclature seems to be that pigments are used in paints and other products (eyeliner, lipstick, nail polish, blusher) but non-pigment colourants are never used in paint (typically toilet cleaner, detergents, candles).

I ran into a problem when I was painting a lightly tinted wall when compared to the white ceiling it looked whiter.

Turned out that ceiling white has a touch of black pigment added. Who knew?

Ian said:

I ran into a problem when I was painting a lightly tinted wall when compared to the white ceiling it looked whiter.

Turned out that ceiling white has a touch of black pigment added. Who knew?

I wish there was a portable colour matcher, a lightweight one that I could carry around. An app?

Ian said:

I ran into a problem when I was painting a lightly tinted wall when compared to the white ceiling it looked whiter.

Turned out that ceiling white has a touch of black pigment added. Who knew?

Me. for a whiter white add a bit of blue. to darken a colour add the colour on the opposite side of the colour wheel and not black. black will make it look “dirty”.

mollwollfumble said:

Ian said:

I ran into a problem when I was painting a lightly tinted wall when compared to the white ceiling it looked whiter.

Turned out that ceiling white has a touch of black pigment added. Who knew?

I wish there was a portable colour matcher, a lightweight one that I could carry around. An app?

you can get apps that do that.

Looking up the Resene paints system for colourants on the web introduced be to the LAB as an alternative to RGB. LAB is a larger colour space than RGB, therefore more suitable for paints.

From wikipedia.

“The Lab color space describes mathematically all perceivable colors in the three dimensions L for lightness and ‘a’ and ‘b’ for the color opponents green–red and blue–yellow. The Lab color space exceeds the gamuts of the RGB and CMYK color models (RGB includes about 90% all perceivable colors). One of the most important attributes of the Lab model is device independence. This means that the colors are defined independent of their nature of creation or the device they are displayed on. The Lab color space is used when graphics for print have to be converted from RGB to CMYK, as the Lab gamut includes both the RGB and CMYK gamut. Also it is used as an interchange format between different devices as for its device independency.”

The full range of variables in LAB is L = 0 to 100 and A and B both = -120 to 120.

But from RGB we can only access A from -90 to 99 and B from -107 to 92.

Interesting.

Some more pictures. My interest is in how paint colouring systems exceed RGB.

https://en.wikipedia.org/wiki/Impossible_color

These impossible colors are of two types:

• Colors that would be seen if the output strengths of the human eye retina’s three types of cone cell (red, green, blue) could be set to values which cannot be produced by exposing the eye in normal seeing conditions to any possible combination of strengths of the frequencies of visible light.
• Colors that cannot be seen directly from any combination of retina signal output from one place in one eye, but can be generated in the brain’s visual cortex by mixing color signals from the two eyes, or from more than one part of the same eye. Examples of these colors are bluish-yellow and reddish-green. Those colors that appear to be similar to, for example, both red and green, or to both yellow and blue. (This does not mean the result of mixing paints of those two colors in painting, or the result of mixing lights of those two colors on a screen.)

A chimerical color is an imaginary color that can be seen temporarily by looking steadily at a strong color for a while until some of the cone cells become fatigued, temporarily changing their color sensitivities, and then looking at a markedly different color.

Bogsnorkler said:

Ian said:

I ran into a problem when I was painting a lightly tinted wall when compared to the white ceiling it looked whiter.

Turned out that ceiling white has a touch of black pigment added. Who knew?

Me. for a whiter white add a bit of blue. to darken a colour add the colour on the opposite side of the colour wheel and not black. black will make it look “dirty”.

It appears that the brewing of Ceiling White is a dark art and one that I hope never to dabble in again..

 Which white for ceilings?

mollwollfumble said:

I wish there was a portable colour matcher, a lightweight one that I could carry around. An app?

Search for “color matching app” gives a heap of them..

Color Grab is the ultimate on-the-go color tool. Pick, capture and recognize colors simply by pointing the camera.

Leading and worldwide used by designers, artists, professionals, developers and color-blinds.

Ian said:

mollwollfumble said:

I wish there was a portable colour matcher, a lightweight one that I could carry around. An app?

Search for “color matching app” gives a heap of them..

Color Grab is the ultimate on-the-go color tool. Pick, capture and recognize colors simply by pointing the camera.

Leading and worldwide used by designers, artists, professionals, developers and color-blinds.

Ta, really useful for paint matching perhaps.

I failed to match the shade of green on my front fence three times running, now the fence is painted four different shades of green.

Michael V said:

kii said:

Oooo….http://www.thisiscolossal.com/2018/01/werners-nomenclature-of-colours/

I have a $25 BN gift card sitting on the desk. Plus free shipping until the 7th…

Should that go into molly’s colourants thread? He might like to buy the book, too.

I thought I’d do it unilaterally.

Michael V said:

Michael V said:

kii said:

Oooo….http://www.thisiscolossal.com/2018/01/werners-nomenclature-of-colours/

I have a $25 BN gift card sitting on the desk. Plus free shipping until the 7th…

Should that go into molly’s colourants thread? He might like to buy the book, too.

I thought I’d do it unilaterally.

Thanks :)

I was thinking of posting it here.

Rule 303 said:

There was a regular on the SSSF forum who was all over this stuff. Postholedigger in paint. A Lurking Chemist?

I’ve been trying to remember the author she used to spruik (I think it was Meg that did it) this morning it came to me Kurt Nassau did a couple of books on colour

Arts said:

Rule 303 said:

There was a regular on the SSSF forum who was all over this stuff. Postholedigger in paint. A Lurking Chemist?

I’ve been trying to remember the author she used to spruik (I think it was Meg that did it) this morning it came to me Kurt Nassau did a couple of books on colour

A former school friend got her doctorate in colour. We had a falling out in recent years over Taylor Swift.

kii said:

Arts said:

Rule 303 said:

There was a regular on the SSSF forum who was all over this stuff. Postholedigger in paint. A Lurking Chemist?

I’ve been trying to remember the author she used to spruik (I think it was Meg that did it) this morning it came to me Kurt Nassau did a couple of books on colour

A former school friend got her doctorate in colour. We had a falling out in recent years over Taylor Swift.

Way back in the pre-electronic age I used to do a lot of plastics colour work with a Lovibond Tintometer. I notice that they are still in operation & now have gone electronic.