Transparency

Sorry to butt into a discussion I don't have a stake in, but the facts as stated below need "adjusting".

> Transparent pigments simply disappear into a darker background.

>... transparent pigments are transparent and will
> be invisible over a darker background no matter how concentrated they
> are printed

> No matter how concentrated you make a transparent pigment, it will
> always be transparent, because that's the inherent nature of the
> pigment.

I paint and I photograph, and use "transparent" pigments all the time, and may be able to make the facts a bit more "transparent" here.

In a perfect world, what are referred to as transparent pigments would be spectrally perfect, and would pass much or all of their color and filter out the rest of the spectrum when applied thickly. So, say, a transparent red would pass all red light through to the substrate where it would reflect back out to the viewer's eye, and all other colors would be attenuated proportionally to the amount of pigment. There would be no opacity - no tendency to reflect light off the pigment direct to the viewer's eye. The dyes in photographic filters are for all practical purposes the model of what a perfect transparent pigment would be. A green filter laid upon a white surface attenuates all non greens heavily and it's own color essentially not at all, and anything not passed is absorbed totally, but not reflected.

In the real world, the so called transparent pigments fall substantially short of that ideal. Some are pretty good, and can be treated as kinda transparent, but most are waaaay short of the performance of the dyes found in photographic filters.

The best transparent pigment colors show their limitations when applied thickly. They exhibit a phenomenon known as "mass tone". Example, one of my colors is known as Indian Yellow, really Diarylide yellow PY83. Very thinly applied over a bright white paper, it makes a strong yellow. A bit more heavily it becomes a stunningly intense golden yellow. It just screams. It's addictive, so you think, I'm going to just gop it on and go into chromatic orgy mode. So, you gop it on and get....dull yellow, kinda muddy.

That's mass tone, seen in most so called transparent colors, a reflection seen best when a thick layer is just trowelled on. Even the best transparent colors don't quite match the performance of the best dyes.

For the most part, most of what a painter would call a transparent color is semitransparent, and those known as semitransparent are semiopaque. Most opaque pigments fall short too, lacking the "covering power" one might wish.

So - if you pile any transparent pigment, in oil or water medium, whtever , onto a black substrate thickly enough, you will see a mass tone, and in some colors, that mass toner will be surprisingly different from the color you expect.

C
Received on Wed Jan 19 08:57:06 2005