Painting & drawing blog
ARE SOME PAINTS POISONOUS?
Exploring the toxicity of pigments and spirits
Health and Safety is rarely an exciting topic, but there are some fairly jaw-dropping stories about the dangerous effects of the paints used by artists in previous centuries. From the Lead White paint thought to have poisoned artists from Michelangelo to Van Gogh, to toxic Vermilion made from mercury, to the infamous, arsenic-containing Scheele’s Green (an earlier version of Emerald Green) which was so poisonous it was apparently deployed to kill rats in Parisian sewers and may have played a part in the death of Napoleon after it was used to paint his walls, it appears that painting was once a genuinely hazardous occupation.
Before the availability of ready-mixed paint tubes painters had to grind pigments themselves or purchase them in powdered form to mix them with an oil binder, creating the conditions for toxic pigments to be inhaled. For centuries contemporary commentators observed a set of mysterious symptoms affecting painters in both mind and body which came to be known as ‘Painter’s Colic’. We now recognize these symptoms as being largely the effects of lead poisoning and even though by the mid 19th century lead paint was coming under suspicion as the cause of the malady, it would be years more before it was was fully abandoned in favour of other white pigments such as Titanium and Zinc. Poor Van Gogh was none the wiser, used both Lead White and Chrome Yellow (lead chromate) and apparently had a habit of licking his brushes.
Whether as some scientists have suggested the effects of lead poisoning could have caused the mental deterioration that culminated in Van Gogh’s suicide is something that can only be speculated about today, but certainly the potentially lethal toxicity of lead is now fully acknowledged and Lead White paint is now banned in most places in the world as a house paint, although exemptions allow it to be sold as an artist’s colour. In the EU however it must be sold in child-proof containers rather than a tube and not kept out on display.
Even though various pigments do derive from heavy metals I’ve always assumed artists’ paints themselves to be fairly safe because the pigments are bound within a medium (an oil such as linseed for oils, a polymer emulsion for acrylics, and Gum Arabic for watercolours) and are not aspirated like a powder. However I did take note of a controversy that raged for several years in the world of art over the EU’s consideration of a proposal to ban Cadmium paint. I’d never given much thought to the toxicity or otherwise of the various substances involved in painting until I was pregnant and it occurred to me to wonder why I’d always get a headache when using Artist’s White Spirit without opening the window!
When I looked into it, I found that hard data on the specific effects of paint pigments and their associated mediums and spirits is nearly impossible to acquire because research has mostly been done into people in factories or mines who are exposed to much larger doses of these substances via airborne exposure. So what exactly is the risk from these traditional heavy-metal derived colours, or from the many new synthetic colours available as alternatives? And in the case of oil painting where unlike in acrylic, watercolour or gouache the paint must be diluted and cleaned with a solvent such as White Spirit rather than water, are the headaches I was getting a sign that these substances should be avoided?
THE SAFETY OF PAINT PIGMENTS
What does your paint actually contain?
Unfortunately, trying to work out what is actually in your tube of paint these days sometimes feels like it requires a chemistry degree! With so many modern synthetic pigments with un-commercial names (Pyrazolo-quinazolone scarlet anyone?) manufacturers produce paints under a marketing name that doesn’t tell you anything about the pigment they contain. Different companies will make a paint with the same name, but using different pigments or combinations of pigments. Sometimes they will still use the name of an old paint that’s now become more or less obsolete due to lightfastness or toxicity concerns.
Vermilion is a good example of all of this. Winsor & Newton sell a ‘Vermilion Hue’ in their Winton oil paint range. This is an accurate description because the word ‘hue’ communicates that this a colour made from a mixture of pigments to resemble the single pigment colour previously made from Vermilion (which came originally either from a mercuric mineral called Cinnebar or from a synthetically created Mercuric Sulphide compound). However whilst there is an industry ‘agreement’ that paint should include the word ‘hue’ when new pigments are substituted for an older single pigment, this is not always practiced. Van Gogh make a colour they describe as ‘Vermilion’ which is really made from a mixture of two pigments: Pyrazolone Orange and Lithol Rubine. Rembrandt’s ‘Vermilion’ is made just from Pyrrol Orange. And Old Holland Vermilion is that Pyrazolo-quinazolone scarlet. These are all technically ‘hues’ and not Vermilion at all.
The only place you’ll be able to find out which pigments are in a tube of paint is usually just a small code which will be printed somewhere on the paint tube, which will start with the letter P. ‘Pyrazolone Orange’ for example will always be indicated with the code ‘PO34’. This code is known as the ‘Pigment Index Number’ and relates to a universal naming system regulated jointly by the British-based Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It allocates every pigment whether organic or synthetic with both a number and an official pigment name and these associations advise that it’s ‘best practice’ to show the name of the pigment as well as the number in plain English, in reality this doesn’t often happen and only a small minority of brands (like these top quality Michael Harding oil paints for example) will clearly write both pigment names and numbers on the front of the tube.
Usually you’ll have to search your paint label to find the tiny Pigment Index number on the back – you can find an example in this article on reading a paint tube. Having located your pigment number/s you can use this handy website to look them up and find out not only which pigments are in your paint, whether they be chemical compounds or derived from natural substances. Orange colours will begin with ‘PO’, reds with ‘PR’, greens with ‘PG’, and so on.
In the case of Vermilion then, you have several companies selling a colour that sounds as if it could derive from a toxic pigment, but actually doesn’t. You will also find a very small number of companies making true Vermilion, derived from Cinnebar, at considerable expense. One of these companies – Michael Harding paints – describes this true Vermilion as being ‘toxic’ and advises caution in its use. What does this really mean however and how can we asses the actual risk involved actually using true Vermilion, or any other of the pigments that derives from a heavy metal?
The exclamation mark sign denotes the more minor hazard to health, and I personally have never even seen one of these on the back of a tube of artists’ paint that I’ve purchased , although I have seen them on solvents. It’s nearly impossible to find out what criteria or testing is employed to determine whether a paint should carry a hazard warning like this – again, the data is very hard to come by because the warnings are largely based on guesswork and the known effects of the pigment source when ingested or inhaled in substantial quantity.
On the back of tubes of paint in both the US and Europe you’ll usually find a little black seal relating to the American ACMI (Art & Creative Materials Institute) and inside this seal will be either a large ‘AP’ (Approved Product’) or ‘CL’ (Cautionary Labeling). If there’s a CL label then in the tube will also contain a specific written warning indicating that the paint may be harmful if swallowed, bad in pregnancy, etc. Underneath the seal you’ll see ‘Conforms to ASTM D 4236’ which simply means that it has been labelled in accordance with the legal chronic hazard labeling standard.
Sometimes there are inconsistencies between information on the paint tube and that published in data sheets online. For instance my Winsor & Newton Cobalt Blue watercolour paint tube contains no hazard warning, but because Cobalt is toxic if ingested or inhaled in large quantities the Data Sheet includes the warning that the paint: ‘May damage fertility. May damage the unborn child.’ The ACMI seal however gives an ‘AP’ approved product label and no cautionary warning. It’s all very confusing.
The evidence for heavy metal toxicity in paint
Given that true Vermilion is still sold today then just how dangerous can it really be? There’s no doubt that the Cinnebar mineral caused the death of many who mined for it in centuries gone by and who inhaled a large quantity of the powdered mineral and suffered from mercury poisoning as a result. However this is very different to using the pigment within a pre-mixed oil, acrylic or gum suspension and there’s no evidence that I can find that modern Vermilion paint has caused health effects. It simply hasn’t been studied. Similarly although there is evidence to support the idea that potters using powdered Cobalt may have suffered from cobalt poisoning there’s no evidence available that simply painting with pre-mixed cobalt paint has ever caused an artist to suffer from Cobalt poisoning.
And what of the controversy over Cadmium? It turns out that the proposal to ban Cadmium within the EU was raised by Sweden, out of concerns that Cadmium was entering the water supply via artists rinsing their brushes in the sink. The idea that there are enough artists using pure, expensive Cadmium paint to cause more than a trace amount of cadmium seemed improbable, especially when compared to the amount leaking from discarded nickel cadmium batteries and sure enough after several years of discussion the EU rejected the proposal.
On the subject of the risk posed by Cadmium Winsor & Newton note online that ‘The level of soluble cadmium in the pigments is so low that no hazard warnings are needed and they pose no greater risk after swallowing or breathing in than other pigment types. Cadmium pigments are restricted for certain applications but this restriction does not apply to artists’ colours’.
Herein really lies the truth, I believe, which is that whereas there may be some small risk from a powder sold as a powder or aerosol – possibly also in the form of a chalky pastel that may create dust – it’s really unlikely that any harm can occur from a pigment used via a prepared tube of paint, even in the long term and particularly if you are careful not to get it all over your hands.
Common sense advice
To sum up then about the risk from paint pigments. Heavy metals are rarely used now by paint manufacturers. Winsor & Newton use no true Vermilion. Hardly any paints will contain mercury, lead or strontium and most certainly not the arsenic which may or may not have poisoned Napoleon! Lead White is available should you wish to use it (a few purists still d0) but it’s hard and expensive to get hold of and the warnings on it will be very clear. I personally wouldn’t use Lead White not least because there are plenty of alternative whites available but as far as other colours go I’m fairly convinced by Winsor & Newton’s assessment of their safety. Their general health and safety information page contains the following advice:
‘Winsor & Newton Artists’ Materials do not present any major hazard when used with care and common sense. It should, however, be emphasised that as with other chemical products, high standards of general hygiene should be adhered to, both during and after use of these products and warnings given on individual products should be followed. Prolonged contact with the skin and ingestion (or swallowing) of the product should be avoided. This includes avoiding practices such as applying colour with the fingers or pointing brushes in the mouth.’
Following these sensible guidelines out of an abundance of caution (to which I’d add not to try to unscrew a paint cap with your teeth!) I’d probably quite happily use true Vermilion or Cadmium rather than a hue of that colour, if I felt that there was no hue imitation that approximated their vibrancy. Indeed I love Cobalt Blue and continue to buy it despite the expense (another reason to switch to ‘hue’ colours is that you’ll save quite a bit of money) I find it hard to believe that the risk is bigger than that posed by many chemicals we already use around the house such as harsh cleaners, house paints, new synthetic carpets and so on. If you’re still concerned, maybe because you are pregnant, you could always wear latex gloves as you paint and keep a window open.
SPIRITS USED FOR OIL PAINTING
We’ve spent a long time discussing the safety of pigments, but it’s actually the spirits or solvents used to dilute or clean up oil paint that first caused me to research into the question of painting safety, and this is the area I feel that the only significant health risk occurs. If you are using watercolour, acrylic or gouache paint then you can both dilute and wash your paint with water.
Oil paints however are insoluble in water and therefore require some kind of spirits to dilute and clean them. It’s possible to thin oil paint just using a paint medium oil such as linseed or poppy oil (this is what your paint in the tube is already mixed with) but the more oil you add to your paint the more glossy it will get and the longer it will take to dry, and so most painters will add spirits such as White Spirit or Turps every time they thin with oils to balance this effect, or will just add a a little of the spirit by itself to improve fluidity (too add much though and your oil paint film will become thin and unstable as it dries, hence the addition of some oil too) Oils like linseed and safflower are entirely non-toxic, but if you aren’t prepared to have very shiny pictures or to start using paint undiluted straight from the tube in an impasto style and maybe applied with a palette knife, then you’re going to have to use some kind of solvent to thin. Either way, you’ll also need some to clean your hands, brushes and palette with.
Turps and White Spirit
Now that turps have fallen out of favour most artists use Artist’s White Spirit which is a purified version of the more common household White Spirit (never use the latter for oil painting as the impurities will damage your paint layers). White Spirit by common consent often causes the same irritant affects as Turpentine such as headaches and nausea. In terms of long term adverse health effects, very lengthy usage (13 years plus of continuous and significant exposure) has been associated with chronic nervous system effects whilst White Spirit has also been implicated in Chronic Toxic Encephalopathy amongst house painters. Legal limits are set by most countries for the levels of exposure per 8 hour work day.
How to minimize exposure
I personally think it wise to avoid daily exposure to White Spirit if you are pregnant. Whether the long term risks are significant for an oil painter again hasn’t really been studied but if like me you take the headaches to be a rather bad indication, there are steps you can take to avoid this.
Always ventilate the room you are working in very well. When using solvents I keep the window open except on the coldest of days, in which case I employ an air filter unit called an ‘Airbubbl’ made by Airlabs which filters out a lot of the VOCs from the air and removes much of the smell. Don’t sleep in a room where you’ve been painting. Keep a lid on your jar of solvents when you can and always overnight.
Low Odor solvents
To avoid te unpleasant smell of solvents there are low odor products such as ‘Sansador’, a slow-evaporating product made by Winsor & Newton. It’s important to be clear that this is still a solvent, and is classified with the H304 warning: ‘May be fatal if swallowed and enters airways.’ Whether it’s really significantly better for health than White Spirit just because it evaporates more slowly is unclear. It’s much more pleasant to work with however as it barely smells and I find it doesn’t give me headaches. ‘Gamsol’ by Gamblin is another option and is also slow drying. Gamblin claims that ‘Gamsol is a petroleum distillate but all the aromatic solvents have been refined out of it, less than .005% remains. Aromatic solvents are the most harmful types of petroleum solvents’, whereas Winsor & Newton don’t actually claim that removing aromatic solvents from Sansodor makes it less harmful for you.
Two other products are worth considering: Winsor & Newton’s popular ‘Liquin’ medium range and Gamblin’s ‘Galkyd’ range. Although described as ‘mediums’ both do still contain solvents too but as with Sansador and Gamsol they are slower to evaporate and have aromatic particles largely removed. Any medium or solvent you add to paint may cause a slight yellowing and may change the consistency of your paint, so you may have to experiment with these options until you find one you like.
It seems that the only way to avoid the use of solvents altogether if you want to continue to paint in oils would be to switch to the one of the new water-mixable oil paint ranges. These paints are made by binding their pigments with a medium of linseed or safflower oil which has been modified by a single molecule, to make it miscible with water. It can therefore be thinned with water (although as usual you’ll need to balance this by adding oil) and can be washed off by water.
Water-mixable oil paint doesn’t handle exactly the same as regular oil paint and the colours may dry to a slightly lighter shade than they appear when wet, but if you can get used to the differences they are undoubtedly the most risk-free type of oil painting. I’d recommend avoiding the cheaper ranges such as Winsor & Newton’s ‘Artisan’ range (find a review here) and Daler-Rowneys’s ‘Georgian Water Mixible Oils’ and instead try Royal Talens ‘Cobra’ paints which have a better consistency and greater range of colours. Other well regarded ranges are available from Holbein or Grumbacher.
A final word about cleaning up your brushes, palettes and yourself when painting with oils because here is really is possible to avoid solvents altogether. Some people use detergent (washing-up liquid) which works quite effectively but I avoid this as I’m concerned about a residue being left on my brushes and contaminating future paint applications. It’s also pretty drying on the hands.
Instead I use ‘The Master’s Soap and Brush Cleaner’ and ‘Brush Cleaner and Preserver’ made by General Pencil and which are non-abrasive. You can buy them online and they work very well. No one is entirely sure what’s in them as the manufacturer keeps their ingredients a trade secret but it’s generally assumed that they contain no toxic ingredients. Remember to wipe your brushes first to get off as much paint as possible.