Nancy W. wrote:

> Thanks Don for writing me back. I think I get it now.  But please bear with me for one more clarification.  Let me see if this is right:  1.00.1 Lemon Yellow Chromate opaque, 1.00.2 Nickel Titanate Yellow PY53 opaque, and 1.00.3 Hansa Yellow Light Arylide PY3 translucent are 3 colors in the ONE DOT that is the outer ring.

Right, all in one dot. The left and right ranges of the dot are not delineated. They are one degree each color. 1.0.5 is the middle of the 10 degree color.

RCW#1.00.1 Light Chrome Yellow, Lead Chromate, PY-34 You probably don't have this one. It's the coolest, lightest, yellow of all. Van Gogh used it in his sunflowers. Blockx may still have it.
RCW#1.00.2 Light, Yellow Light Hansa,  Arylamide,  PY3, Translucent
RCW#1.00.2, Nickel Titanate Yellow PY53
RCW#1.00.3, Hansa Yellow, Monoazo Yellow, PY-74, Translucent

> Then 1.0.1 Zinc Yellow opaque through 1.0.9 Flavanthrone Yellow Vat Yellow 1, PY12 transp are all in the ONE DOT that is the second ring of pure yellow.

Right, the pure mass-tone, right out of the tube. They range from the left side, the cooler side, the side of the next color over, #36 Yellow -Green to warm.

> They are not perfect yellows, but 0.1-0.10 in range of 1.0.  Am I correct in this?

No, that's not correct. The Arc number always starts with the color number, from one to thirty six and there are no dashes in the system.
The second set of numbers is the vertical axis of value, from tint 1.00 to 1.10, 10 being the darkest block in the set.
The third set is the 10 degree warm to cool span of that color, 1.10.5

>   Also is the closer to 1.0 the more pure the color?

Yes. 1.0 is the mass color, 1.0.5 is understood as it is the center of that block of color.
1.0.5 is the purest hue mass color of Arc number one.
1.0.1 is the coolest hue, 1.0.5 is the middle between 1.0.1 and 1.0.9. 1.0.5 is the perfectly centered mass color. If the color is only written as 1.0, the 1.0.5 is understood.
1.10.5 is the darkest color in the arc #1.

RCW#1.0.1, Cadmium Zinc Sulfide, PY35, Opaque (cool)
RCW#1.0.2, Cadmium Lemon, PY35, Opaque (cool-warm))
RCW#1.0.3, Bismuth Yellow PY184 (warm-cool)
RCW#1.0.5, Aureolin, Potassium Cobaltinitrite, PY40, Translucent (middle)

> If this is right, then I think I can finally get my paints and fill my palette!  If I am wrong, please help me figure this out!

>Thank you for your patience!

It's my pleasure,
Don