Pigments question

[avram]

Anyone who knows a lot about pigments out there who can explain this to me? See, I’ve got some ideas that involve using strong washes of transparent color, so I need to stock up on transparent fluid acrylics. I like Golden brand, because they’re one of the two major brands with a wide range of colors that you can get just about anywhere, and in my experience their fluid colors flow more easily than Liquitex’s.

Behind the cut is a list of the colors Golden Acrylics makes, sorted by transparency/opacity rating. Those rated 8 are the most transparent, 1 the most opaque. (I dunno what’s up with Transparent Pyrrole Orange. It’s got “NA” for most of its characteristics, so maybe it’s new and they haven’t gotten to testing it yet, or it fell out of their database, or something.)

NA -- Transparent Pyrrole Orange
8 -- Transparent Yellow Iron Oxide
8 -- Transparent Red Iron Oxide
7 -- Zinc White
7 -- Quinacridone Red Light
7 -- Quinacridone Magenta
7 -- Quinacridone Gold
7 -- Nickel Azo Yellow
7 -- Hansa Yellow Medium
6 -- Ultramarine Blue
6 -- Quinacridone Red
6 -- Primary Yellow
6 -- Hansa Yellow Light
5 -- Vat Orange
5 -- Ultramarine Violet
5 -- Quinacridone Crimson
5 -- Quinacridone Burnt Orange
5 -- PyrroleOrange
5 -- Naphthol Red Medium
5 -- Hansa Yellow Opaque
5 -- Diarylide Yellow
4 -- Quinacridone Violet
4 -- Primary Magenta
4 -- Naphthol Red Light
4 -- Green Gold
3 -- Turquois(Phthalo)
3 -- Raw Sienna
3 -- Pyrrole Red Light
3 -- Pyrrole Red
3 -- Primary Cyan
3 -- Phthalo Green (Yellow Shade)
3 -- Phthalo Green (Blue Shade)
3 -- Phthalo Blue (Red Shade)
3 -- Phthalo Blue (Green Shade)
3 -- Permanent Violet Dark
3 -- Permanent Green Light
3 -- Dioxazine Purple
3 -- Cobalt Teal
3 -- Cobalt Blue
3 -- Cerulean Blue, Chromium
3 -- Cerulean Blue Deep
3 -- Cadmium Yellow Medium Hue
3 -- Cadmium Red Medium Hue
2 -- Yellow Ochre
2 -- Titanium White
2 -- Titan Buff
2 -- Paynes Gray
2 -- Jenkins Green
2 -- Cobalt Turquois
2 -- Burnt Umber Light
2 -- Burnt Sienna
2 -- Bone Black
2 -- Anthraquinone Blue
1 -- Yellow Oxide
1 -- Violet Oxide
1 -- Red Oxide
1 -- Raw Umber
1 -- Chromium Oxide Green
1 -- Carbon Black

OK? Thing is, when I checked my copy of The Acrylic Painter’s Pocket Palette, it listed only four colors (Pthalo blue, Pthalo green, Naphthol crimson, Dioxazine purple) as transparent (one of three ratings; the others are translucent and opaque), and the three of those that Golden makes are all rated 3 or 4, closer to the opaque end of the scale than the transparent one. OK, the book is probably mostly drawing on traditional colors, and avoiding the recent synthetics, so its idea of “transparent” might have been transcended by recent science.

I’ve got some jars of Liquitex fluid acrylic here, and the Pthalo green says it’s transparent (but they don’t use a numeric scale). Liquitex’s Yellow light hansa is also transparent, while Golden’s Hansa yellow light is rated 6. Does this mean that everything from 3 to 8 on Golden’s scale is considered transparent? What kind of goofy scale is that?

On the other hand, the extraordinarily comprehensive Handprint guide to watercolor paints (which uses a five-point scale, with 4 as most transparent and 0 as most opaque) lists most Pthalo blues as 4s, while Arylide yellow 10G (the pigment in Hansa yellow light) paints run from 2 to 4 depending on manufacturer.