Color Curriculum

What Information Is Important on a Tube of Paint?  

By Carolyn Payzant 

Originally appeared in The Botanical Artist – Volume 16, Issue 3

 

Marketing Name 

The marketing name doesn’t mean a thing. Manufacturers pay people to think up names to induce you to purchase. One winter in New Hampshire I bought “Sandal Red” which turned out to be less than satisfactory in the lightfast category. Later I found out it is similar to Winsor Red. But somehow in the middle of winter Winsor Red doesn’t conjure up the same visions. 

“Hue” in the marketing name sometimes means the paint does not actually contain the pigment labeled and could be student grade paint, which is a no-no in fine botanical art.  

Lightfastness (LF) 

The American Society for Testing and Materials (ASTM) developed standards that many manufacturers have adopted for permanency. This is great for the artists but there is one glitch; the manufacturer must pay ASTM to do the testing. A few manufacturers want to skip this cost and do their own testing and come up with their own categories. Some will use a letter designation (A or AA), and some a numeric designation (using 5 as their best rating). As many of you are aware, I am about as market driven as anyone, but even I know not to let the fox watch the hen house. 

ASTM Categories 

LFI: Excellent under all normal lighting conditions 

LFII: Very good, except when exposure to ultraviolet light. 

All other categories are problematic: LFIII can fade. LFIV fades promptly. LFV bleaches promptly. (TBA, March 2006, p. 5.) Sometimes lightfastness is written “Not Rated.” Call me suspicious, but why? Some manufacturers say that a pigment has not been tested before marketing. Again I ask, why? I assume the issue is that the manufacturer wants the pigment on the market before ASTM testing. So ask yourself, do you want to take a chance with a pigment that is Not Rated?  

Color Index 

This one is a no brainer; PB = Pigment Blue, PY = Pigment Yellow, etc. Note, NR = Natural Red. 

By the way, each number has a specific chemical formulation assigned to it. Therefore, PR176 is always Pigment Red Benzimidazolone Carmine. The marketing name should be carmine. But not all carmine’s are created equal and some are fugitive. Carmines are made with PR5, NR5, PR83, PR146….I think you get the idea! Only purchase PR176 when purchasing carmine. 

Chemical Content 

Don’t trust the marketing name on a tube of paint. I never gave any thought to the chemical content of paint until I took Susan Fisher’s Color Mixing Workshop, and she required cadmium yellow. I, for one, could not get the color that she felt we should be able to mix. On examining the tubes, some in the class had PY35 cadmium yellow and I had PY37 cadmium yellow. Cadmium yellow PY35 is cadmium zinc sulfide which is green bias and cadmium yellow PY37 made of pure cadmium sulfide which is the red (orange) bias. The hidden culprit was zinc. 

Transparency/Opacity 

Again, a no brainer! Just know, when you mix an opaque paint with another opaque or semi-opaque paint you may create mud. However, you can create luscious colors by mixing a transparent or semi-transparent paint with any opaque or semiopaque paint.  

Oh, if it were that simple. When mixing a transparent or semitransparent paint with any opaque or semi-opaque paint the transparent or semi-transparent paint is reduced to the lowest common denominator – the transparent/semi-transparent paint becomes semi-opaque to opaque. Mix carefully. 

Toxicity 

One last interesting number is D4236. This refers to the Chronic Health Hazards in Pigments. ASTM requires a notation of toxicity, but does not require the manufacturer to state what type of toxicity, how serious the toxicity is, how long you must be exposed to the toxicity to incur significant health risk. This is a direct quote from the ASTM website, “D4236-94 (2005) this standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulation limitations prior to use.” My recommendation: If the tube says it is toxic, please use that pigment with care. 

Information I Wish Were On the Tube 

Percentage of drying shift, tinting strength, stainability, bias, and granulation.