Re: Traditional palette vs. modern 582 by Steve Sauer on 05/26/01 at 3:07 AM
Re: Traditional palette vs. modern

In Reply to: Re: Traditional palette vs. modern posted by Ed on 05/23/01 at 8:54 PM:

"What causes that color change?"
"I get the impression that this is one of those questions they still don’t have an adequate answer for."

Hmmm.. No answer is no answer.

"That means mercuric sulfide is not light sensitive."
"Nope, it is, or more correctly CAN be."

This statement is erroneous. Unless there are multiple molecular forms of mercuric sulfide, the chemical properties of the pure compound are universal. There is only one molecular form of mercuric sulfide, correct?

"Look it up if you have any doubts."

I have read numerous sources, and many of them conflict. Most of them point to adulterants and impure sources of mercuric sulfide for causing color changes.

"If it was, all samples of Vermilion would have blackened."
"No, that does not follow - some obviously haven’t but more importantly some have and before you say it, yes, even pure pigment with no red lead."

There must be a cause. If some have not blackened, then Vermilion cannot be light sensitive in itself. I doubt these old paintings have been stored in utter darkness since they were painted.

"Just which organic blue are you referring to? Surely not the phthalocyanines???? They are among the most stable pigments known."

They are among the most stable synthetic organic pigments known, yes. Put them in a contest with pure carbon, and I bet the carbon would win. Put them in a heat test against cobalt blue, and I would think cobalt would win.

"The only other synthetic organic blue I am aware of is Indanthrone blue (PB60) which I don’t use but I think is ASTM I also."

Yes, but ASTM I or not, it is not nearly as permanent as the most permanent inorganic blues. That was my point.

"Reasonable permanence is acceptable. Cobalt yellow, for example..."
: I don’t use this but in oils I think it is ASTM II, which is actually better than reasonable permanence in most people’s books.

And, many people will not use Cobalt Yellow, because they don't consider it permanent enough. For them it's ASTM I or nothing. For some, the ASTM ratings are not even strong enough. ASTM I means the pigment will last for 100 years with indoor lighting, correct? I believe that many ASTM I rated pigments are not suitable for outdoor use, because they will not last. The ASTM ratings are useful, but they are not omniscient.

"The same thing is often said about cadmium colors, too... Should we also not use cadmium colors?"
: Come on! The fault here is the Flake White, not the cadmium colours!"

You missed the point. Cadmium colors are cadmium sulfide (and selenium and other metals) and Vermilion is mercuric sulfide. Both can blacken white lead. My point is clear.

"And from my research this is only with cadmium colours where there is free sulphur remaining, which is rare in modern manufacturing processes."

That was one of my points about the Vermilion. Free sulphur and polluting sulfur compounds may contribute to Vermilion's poor reputation for mixing with white lead.

"Anyone with concerns in this regard should do accelerated lightfastness tests like I am in the process of doing, just to make sure. A test I found on the net showed virtually no difference after a year of exposure to direct sunlight but I’m repeating it to be sure."

I saw that test site; Vermilion was not tested, was it?

While it quite obviously has not altered in some cases, it just as obviously has in others and they are uncertain as to the reasons for its failure."

I have already provided many explanations and you've denied them all. The fact that many examples of lightfast Vermilion exist proves that the compound mercuric sulfide is lightfast. If it was not lightfast, every example of Vermilion would have blackened.

"Why do you think the colourmen went searching for a replacement to one of their best-selling colours????"

Because, Vermilion is expensive. It's always been expensive. It's toxic. (Many colourmen are replacing Cadmiums for the same reason.) It has an uncertain reputation because it has such a long history of being adulterated. Poor manufacturing also certainly played a role. (The sulphur and sulphur compounds.) It's a lot easier for a colourman to make a tube of Naphol and sell that. The pigment is cheaper, it's not toxic, and the colourman can point to the ASTM rating in order to sell the product easily. It's unfortunate that I have samples of Naphols that have faded in a matter of weeks in normal lighting and completely when mixed with zinc white. Naphol AS-OL PR-9.

When there are examples of bright red Vermilion on paintings that are hundreds of years old and I have Naphol paints that fade in a few months or even weeks, I am less inclined to blindly trust ASTM ratings.

"Alizarin Crimson is one of the biggest failures in this regard as apparently it will fade in light tints and glazes even in the dark and this is hardly news."

Yes, Alizarin is certainly the most popular fugitive pigment. Natural madder is even worse. However, I've read that some of the "replacement" organics can show fading in tints. They are significantly more permanent than Alizarin, but perhaps not quite permanent enough to be called permanent. And, their properties are not often similar. Quinacridone "Permanent Alizarin Crimson" looks and performs nothing like real Alizarin.

"Grinding cadmium colors is just as toxic."
"No it is not, do your research. While I wouldn’t suggest cadmium is not a health risk their toxicities are not nearly the same. - cadmium is far less toxic than mercury."

Soluble mercury.. yes. Insoluble mercury is a whole different matter.

"To quote one source: 'as a matter of record toxic effects from cadmium almost never occur.' I don’t mean to be obtuse but do you know the WHO guidelines for safe levels of mercury? Zero."

Should I sue my dentist for putting mercury-containing fillings in my teeth? I haven't died yet. And, some have said that dentists are scaring people in order to get them to come in and get them all replaced.

Why not list the effects of cadmium in the body?

"Check out this link if you have any doubts about the toxicity of mercury:

"The distinction between elemental, inorganic and organic mercury is much more important than oxidation states in determining toxicity, as organic mercury compounds are the most toxic"

"Inorganic mercury mainly causes poisoning by ingestion"

"Cadmium has no essential biological function and is extremely toxic to humans."

Those are quotes from your source.. The source you posted is similar to those I have read. Organic mercury is extremely dangerous, yes. I've said that.

"Yes, but it still poses a significant health risk."

No kidding. Please also refer to the quote above concerning cadmium.

"Flake white is actually far more dangerous to work with than Vermilion"
: Sorry but this is patently false! I don’t mean to be rude but please do your research before spreading misinformation like this.

"Lead is FAR LESS toxic than mercury, if it wasn’t we’d all be dead from the lead in the environment from leaded petrol."

Organic mercury is not relevant to this discussion! Flake white is more dangerous than Vermilion because it is organic and contains soluble lead.

"Emerald green is far more toxic than Vermilion."
"Yes of course it is. But that doesn’t make Vermillion non-toxic."

Really? How insightful.

As far as I am aware there are only two or three forms of phthalo blue (PB15:1 to PB15:3) and two of green (PG7 and PG36) commonly made into paints which is hardly 30"

That's 5 pigments. 5 Pigments just for Phalo. Add up all of the many variations of Naphol and the other organics. Put them all together and what do you have? Something that's very complex.

"If anyone is committed to producing work of permanence it is easily within their grasp to find out the basics of sound pigment choice and in a short time. It is also much easier today than it was only a decade ago."

As you said, reputable dealers are selling fugitive paints. Easy? Hardly..



Follow Ups:

Re: Traditional palette vs. modern Ed   Posted at: 05/26/01 (2)
Re: Traditional palette vs. modern Steve Sauer   Posted at: 05/27/01 (1)
Re: Traditional palette vs. modern Ed   Posted at: 05/28/01 (0)

Post a Followup 545,548,555,560,565,566,573,582"> Steve Sauer"> stevesauer_hotmail.comRe: Traditional palette vs. modern_05/26/01 at 3:07"Re: Traditional palette vs. modern"
: "What causes that color change?" : "I get the impression that this is one of those questions they still don’t have an adequate answer for." : Hmmm.. No answer is no answer. : "That means mercuric sulfide is not light sensitive." : "Nope, it is, or more correctly CAN be." : This statement is erroneous. Unless there are multiple molecular forms of mercuric sulfide, the chemical properties of the pure compound are universal. There is only one molecular form of mercuric sulfide, correct? : "Look it up if you have any doubts." : I have read numerous sources, and many of them conflict. Most of them point to adulterants and impure sources of mercuric sulfide for causing color changes. : "If it was, all samples of Vermilion would have blackened." : "No, that does not follow - some obviously haven’t but more importantly some have and before you say it, yes, even pure pigment with no red lead." : There must be a cause. If some have not blackened, then Vermilion cannot be light sensitive in itself. I doubt these old paintings have been stored in utter darkness since they were painted. : "Just which organic blue are you referring to? Surely not the phthalocyanines???? They are among the most stable pigments known." : They are among the most stable synthetic organic pigments known, yes. Put them in a contest with pure carbon, and I bet the carbon would win. Put them in a heat test against cobalt blue, and I would think cobalt would win. : "The only other synthetic organic blue I am aware of is Indanthrone blue (PB60) which I don’t use but I think is ASTM I also." : Yes, but ASTM I or not, it is not nearly as permanent as the most permanent inorganic blues. That was my point. : "Reasonable permanence is acceptable. Cobalt yellow, for example..." I don’t use this but in oils I think it is ASTM II, which is actually better than reasonable permanence in most people’s books. : And, many people will not use Cobalt Yellow, because they don't consider it permanent enough. For them it's ASTM I or nothing. For some, the ASTM ratings are not even strong enough. ASTM I means the pigment will last for 100 years with indoor lighting, correct? I believe that many ASTM I rated pigments are not suitable for outdoor use, because they will not last. The ASTM ratings are useful, but they are not omniscient. : "The same thing is often said about cadmium colors, too... Should we also not use cadmium colors?" Come on! The fault here is the Flake White, not the cadmium colours!" : You missed the point. Cadmium colors are cadmium sulfide (and selenium and other metals) and Vermilion is mercuric sulfide. Both can blacken white lead. My point is clear. : "And from my research this is only with cadmium colours where there is free sulphur remaining, which is rare in modern manufacturing processes." : That was one of my points about the Vermilion. Free sulphur and polluting sulfur compounds may contribute to Vermilion's poor reputation for mixing with white lead. : "Anyone with concerns in this regard should do accelerated lightfastness tests like I am in the process of doing, just to make sure. A test I found on the net showed virtually no difference after a year of exposure to direct sunlight but I’m repeating it to be sure." : I saw that test site; Vermilion was not tested, was it? : While it quite obviously has not altered in some cases, it just as obviously has in others and they are uncertain as to the reasons for its failure." : I have already provided many explanations and you've denied them all. The fact that many examples of lightfast Vermilion exist proves that the compound mercuric sulfide is lightfast. If it was not lightfast, every example of Vermilion would have blackened. : "Why do you think the colourmen went searching for a replacement to one of their best-selling colours????" : Because, Vermilion is expensive. It's always been expensive. It's toxic. (Many colourmen are replacing Cadmiums for the same reason.) It has an uncertain reputation because it has such a long history of being adulterated. Poor manufacturing also certainly played a role. (The sulphur and sulphur compounds.) It's a lot easier for a colourman to make a tube of Naphol and sell that. The pigment is cheaper, it's not toxic, and the colourman can point to the ASTM rating in order to sell the product easily. It's unfortunate that I have samples of Naphols that have faded in a matter of weeks in normal lighting and completely when mixed with zinc white. Naphol AS-OL PR-9. : When there are examples of bright red Vermilion on paintings that are hundreds of years old and I have Naphol paints that fade in a few months or even weeks, I am less inclined to blindly trust ASTM ratings. : "Alizarin Crimson is one of the biggest failures in this regard as apparently it will fade in light tints and glazes even in the dark and this is hardly news." : Yes, Alizarin is certainly the most popular fugitive pigment. Natural madder is even worse. However, I've read that some of the "replacement" organics can show fading in tints. They are significantly more permanent than Alizarin, but perhaps not quite permanent enough to be called permanent. And, their properties are not often similar. Quinacridone "Permanent Alizarin Crimson" looks and performs nothing like real Alizarin. : "Grinding cadmium colors is just as toxic." : "No it is not, do your research. While I wouldn’t suggest cadmium is not a health risk their toxicities are not nearly the same. - cadmium is far less toxic than mercury." : Soluble mercury.. yes. Insoluble mercury is a whole different matter. : "To quote one source: 'as a matter of record toxic effects from cadmium almost never occur.' I don’t mean to be obtuse but do you know the WHO guidelines for safe levels of mercury? Zero." : Should I sue my dentist for putting mercury-containing fillings in my teeth? I haven't died yet. And, some have said that dentists are scaring people in order to get them to come in and get them all replaced. : Why not list the effects of cadmium in the body? : "Check out this link if you have any doubts about the toxicity of mercury"The distinction between elemental, inorganic and organic mercury is much more important than oxidation states in determining toxicity, as organic mercury compounds are the most toxic" : "Inorganic mercury mainly causes poisoning by ingestion" : "Cadmium has no essential biological function and is extremely toxic to humans." : Those are quotes from your source.. The source you posted is similar to those I have read. Organic mercury is extremely dangerous, yes. I've said that. : "Yes, but it still poses a significant health risk." : No kidding. Please also refer to the quote above concerning cadmium. : "Flake white is actually far more dangerous to work with than Vermilion" Sorry but this is patently false! I don’t mean to be rude but please do your research before spreading misinformation like this. : "Lead is FAR LESS toxic than mercury, if it wasn’t we’d all be dead from the lead in the environment from leaded petrol." : Organic mercury is not relevant to this discussion! Flake white is more dangerous than Vermilion because it is organic and contains soluble lead. : "Emerald green is far more toxic than Vermilion." : "Yes of course it is. But that doesn’t make Vermillion non-toxic." : Really? How insightful. : As far as I am aware there are only two or three forms of phthalo blue (PB15:1 to PB15:3) and two of green (PG7 and PG36) commonly made into paints which is hardly 30" : That's 5 pigments. 5 Pigments just for Phalo. Add up all of the many variations of Naphol and the other organics. Put them all together and what do you have? Something that's very complex. : "If anyone is committed to producing work of permanence it is easily within their grasp to find out the basics of sound pigment choice and in a short time. It is also much easier today than it was only a decade ago." : As you said, reputable dealers are selling fugitive paints. Easy? Hardly..

 
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