PG21- TOXICITY=Extremely Toxic [contains Arsenic and Copper]
REACTIVITY= Highly Reactive to Sulfur
PERMANENCE= Not Permanent. Hue shifts after a few weeks to a month
LIGHTFASTNESS= Lightfast (II)
I would like to share with you all some research that I have compiled in regards to one of the most infamous pigments in paintings history. This pigment is of course "Emerald Green", also known as "Paris Green", and "Veronese Green", as well as a host of other less commonly used names.This pigment was the breakthrough green pigment of the 1800's, as it was very vivid, and it wasn't a mixture or a hue, it was a single pigment color like nobody had seen by the time it was released. It was first synthesized in Schweinfurt, Germany by two men, Russ and Sattler around the year 1814 in an effort to improve on the chemically similar "Scheele's Green", as this new green was meant to be more stable. Both were incredibly toxic however.
Chemical Composition of "Scheele's Green" - (copper arsenite)
Chemical Composition of "Emerald Green" - (copper(II) acetoarsenite)
Both pigments contained elements of Copper as well as Arsenic, which made them very dangerous if used improperly. Toxic pigments were nothing new in the art world, however- we had been using heavy metal based pigments for 1000's of years at this point, including both copper and arsenic based pigments. In fact, the only white based paint we had until the 1800s and the introduction of Zinc White was "Flake White" (Lead Carbonate). One key difference is that in the 1800's the world was changing vastly and many of the ways people in this time period handled things were very dangerous and flat out strange to us now. They didn't know any better.
Cocaine was part of the Original Coca-Cola beverage, Heroin was essentially a medicine, deadly pigments containing lead, copper, mercury, and arsenic were routinely used in all forms of decoration [oil paint, house paint, clothing dye etc.]. Emerald Green as a dry powder pigment was also used as an insecticide during WW2, as well as a rodenticide in Paris sewers [hence the name Paris Green. If there was ever a time in history to be living on the edge, it was the 1800's. Emerald Green went out of production around the 1960's once it finally became banned to produce and sell. There are still ways to obtain it as a dry pigment, but it can't be commercially sold, and generally has overall been replaced by much safer alternatives, mostly hue combinations of yellow, blue, white, and the Pthalo colors. It is very difficult to come by Emerald Green these days, you can get the dry pigment through hard to find sales via the internet, also you may be so lucky to stumble upon Vintage intact oil paint tubes, like I did.
I stumbled upon these 4 vintage Emerald Green in the spring of 2016 through sources in which I will keep to myself.
The tubes listed are as follows (From Left to Right)
1. Emerald Green- Rowney & Co. - Very Old, likely Early 1900's
2. Emerald Green- Rowney Georgian - 1940's-1950's
3. Emerald Green- Roberson & Co. - Likely the oldest of the bunch, Late 1800's- Early 1900's
4. Emerald Green- Winsor & Newton - 1920-1950 ?
All of the tubes are 60-100+ years old. Pretty cool, I know. I also have an old tube of Carmine oil paint dated at 1889 that id like to test and show off eventually as well.
I have conducted some tests regarding the performing characteristics of Emerald Green. Among these tests are
-Pigment in practice
1st Test- REACTIVITY
1 MONTH TIMELAPSE FROM TOP TO BOTTOM SAMPLES - 6/9/16 -7/9/16
In this test I have taken 5 genuine vintage Emerald Green oil paints,
1 genuine Malachite oil paint,1 suspect Emerald Green labeled as "Emerald Stone Green" on the tube dated to be from early 1900's, and mixed all 7 tubes with Cadmium Yellow to see if the sulfur content would react with the copper content within these 7 colors. The results tell it all. The 5 genuine Emerald Green's [Copper/ Arsenic based] turned dark green/ blackish. The Malachite didnt seem to be affected by the introduction of a sulfur containing paint. This caused suspicion as to whether it was the copper, or the arsenic in the Emerald Green's harshly reacting with the sulfur in the Cadmium Yellow. Judging by this test I would have to say that it was the Arsenic that was reacting harshly to the sulfur, as the Malachite didnt seem to react [Copper Carbonate] The "Emerald-Stone Green" appeared to not be genuine, very likely a very old hue-imitation of Emerald Green, as it didnt change at all with the introduction of the Cadmium Yellow [Sulfur bearing pigment]
I did some additional studies regarding the reactivity of this pigment.
I mixed a different pigment with Emerald Green that also contains Sulfur, like the cadmium yellow prior.
1 MONTH TIMELAPSE FROM TOP TO BOTTOM SAMPLES -6/19/16 - 7/19/16
Blue pigment being used is Ultramarine Blue (A complex sulfur-containing sodium aluminum silicate)
The shift over a one month period of time between Ultramarine Blue and Emerald Green is subtle. I definitely detect a shift in hue, as seen with the cadmium/ emerald mixtures, although not as strong. This could be for a variety of reasons. There could be a lower Sulfur content in Ultramarine Blue vs Cadmium Yellow, and/or it could be the fact that the hue of Emerald Green in oil paint form naturally shifts in hue- which I have found and documented that it does. In this test sample you can see Ultramarine Blue alone, Emerald Green alone, as well as the mixture between the two, and then you can see the changes brought on by a month of waiting. If you look at the small sample of Emerald Green on the right on both pictures you will see that Emerald Green slightly shifted on its own. I have noticed this in all of my Emerald Green samples. It isnt a permanent pigment in the sense that its hue does shift. More on this later.
1 MONTH TIMELAPSE FROM TOP TO BOTTOM SAMPLES -5/9/16 - 6/9/16
Left to Right"
"Moss Green- Vintage 1889 French Oil Paint
"Emerald Green hue" - Marie's
"Emerald Green hue" - Old Holland
Genuine Emerald Green- Matuda
This picture samples mostly Emerald Green HUES, as well as one Genuine Emerald Green mixed with Cadmium Yellow. You can easily see the difference between the hues vs the genuine Emerald Green when mixed with the Cadmium Yellow. The Emerald hues dont change after the one month, while the genuine Emerald Green has began to darken drastically, due to presence of Sulfur in the Cadmium Yellow and Copper/ Arsenic in the Emerald Green.
CONCLUSION- Emerald Green is HIGHLY reactive with Sulfur, and will darken upon being exposed to it.
2nd Test- LIGHTFASTNESS
During the summer of 2016 I decided that I was going to study Emerald Green (PG21) with some standard tests to share valuable data with other art history fans. The timing was perfect, as I was able to also document the Lightfastness of Emerald Green via making 2 identical test strips containing 2 different Emerald Green HUES, as well as 2 different Emerald Green GENUINE oil paints- Keeping 1 indoors out of the sun, and the other in a window to capture the full North American sunlight for 3 months. Usually, it is recommended to expose the paint strip to direct sunlight for 1 full year to get the best results, but I figured 3 months in the summer sun should at least bare some acceptable changes in my results.
TEST STRIP ON LEFT= INDOOR
TEST STRIP ON RIGHT= OUTDOOR FOR 3 MONTHS [ 6/2/16 - 9/2/16 ]
The color samples used are as follows-
Top- Emerald Green GENUINE - Matuda
Right- Emerald Green HUE - Rowney
Bottom- Emerald Green HUE- Old Holland
Left- Emerald Green GENUINE- Winsor & Newton
You can see from this side by side comparison that there is a subtle difference between the left and the right panel. The right panel all color samples seem to slightly be showing a chalking effect that I believe would be more noticeable had I exposed them for a year, instead of 3 months. I notice no significant differences between the hues and the genuine Emerald Greens.
CONCLUSION- I would say that Emerald Green is Lightfast, meaning that exposure to UV isnt a huge issue in the immediate future of a painting containing Emerald Green, however it isnt ultra-resistant either. It sits in the middle ground level with a rating of II.
3rd Test- TRANSPARENCY
Bone Black on the Left
Lead White on the Right
With this test I am trying to figure out just how transparent Emerald Green really is. As you can see in the photographic testing above, I have thinned Emerald Green down and did 4 thin layers over the Bone Black and the Lead White with graduating opacity as the layers move downwards. In all layers over both the black and the white you can see that it is definitely slightly transparent, although not overbearingly. It lays in a middle ground area. Through my actual testing of Emerald Green in an actual painting it tends to become slightly transparent even without a thinner medium if spread out, although as I said- it isn't on the high end of transparency, more along the lines of somewhere in the middle.
You can see the mixture of Bone Black + Emerald Green and the mixture of Lead White and Emerald Green in the second photo. The tinting strength is medium, coinciding with its transparency rating.
CONCLUSION- I rate Emerald Green as Semi-Transparent [2.5 / 5]. and is a medium opacity tinter.
4th Test- PERMANENCY
This test was a bi-product of other tests, as in I wasn't originally planning on testing the permanency of Emerald Green but through my testing of its reactivity I noticed that Emerald Green shifted in hue on its own, without being exposed to sulfur. I found this very odd so I figured I would conduct a little research on how much time it took, and how drastic the changes generally were. In this 1st photo, you can see a mini- time lapse of how the color shifted from its original hue to something else gradually over the period of some months.
1st panel= 6/9/16
2nd Panel= 7/9/16
3rd panel= 10/28/16
The amount the original minty Emerald Green hue has gradually shifted in almost 5 months is very evident, and while the color hasnt necessarily darkened, it has dulled to an extent and become a more "poison" looking green more in hue of Scheele's Green ironically.
Left= Fresh Emerald Green [ 10/28/16 ]
Right= Dry Emerald Green [ 8/9/16 ]
Clear evidence that the minty hue of Emerald Green fresh out of the tube isnt permanent. It ALWAYS [in all of my research] shift a little more to a grassy/ poison emerald green color and loses the minty intensity it has while fresh out of the tube.
CONCLUSION- Emerald Green is a beautiful single pigment color, but it definitely isn't a permanent pigment. If one were to use it [unless you're using it for restoration, or historical integrity practices I wouldn't recommend it] it will not keep its original hue. It will very quickly shift from minty emerald green to a grassy emerald green. This shift happens in a matter of a few weeks to a month. The change is very quick, and I'm not sure how much it will shift over time. I have only been testing since May of 2016.
5th Test- PIGMENT IN PRACTICE
"Little Boy"- Oil On Linen/Panel, 2016
To top off my research on the working properties of Emerald Green, I figured id show off a painting that I painted primarily using Emerald Green unmixed in a bulk of the painting. This painting rings true many of my findings above. You can see Emerald Green's transparency in the body of the bomb capsule, you can see some of the lead-oil primed linen panel beyond the thin veil of Emerald Green. You can also see thicker areas where I used Emerald Green straight, where it isn't transparent. Also, I made sure that I used the Emerald Green with Genuine Naples Yellow, as there is no reactivity between the two! [due to lack of sulfur] plus in all honesty genuine Naples Yellow is the most beautiful yellow in my opinion. Also, this one was kinda a bonus- but the painting is of the bomb dropped on Hiroshima [in my own painting style of course] and the pigment I'm using is one of the deadliest pigments around. Both synthetic, man-made destruction. Kind of a cool little coincidence in my opinion.
Well, this concludes my 1st entry on Emerald Green. I will be posting more on Emerald Green in the future on this SAME blog. I have 1 more major test I would like to conduct, as well as a few smaller things too.
Until next time, take care folks!
Watch a brief verbal explanation of my Emerald Green findings