Painting & drawing blog
ARE SOME PAINTS POISONOUS?
Exploring the toxicity of paint pigments, binders 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 the toxic Vermilion made from mercury. 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.
Detail from Wheat Field Behind Saint-Paul Hospital with a Reaper by Vincent Van Gogh, 1889
Public domain. Photo credit: Museum Folkwang
Before the availability of paint tubes painters had to grind pigments themselves or purchase them in powdered form, 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 having usually been the effects of lead poisoning. Although by the mid-nineteenth 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 obviously none the wiser: he used both Lead White and Chrome Yellow (lead chromate) colours frequently 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. Certainly the potentially lethal toxicity of lead is now fully acknowledged and paint made from lead 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 put out on display.
Although though various pigments do still derive from heavy metals (including cadmium, chromium, cobalt, copper, lead, manganese and zinc) I’ve always assumed that in the context of artists’ paints these would be fairly safe, because the pigments are not handled in the form of a powder or a spray that can be inhaled. Instead they arrive in the art shop bound in the tube within a medium (an oil such as linseed for oil paint, a polymer emulsion for acrylics and gum arabic or a synthetic binder for watercolours). However I did take note of a controversy that raged recently over the EU’s consideration of a proposal to ban all paint made from cadmium, and was aware that my paint tubes carried warnings intended for the US market including admonishments that cadmium was known to be carcinogenic.
I still took no real notice and it was only when I was expecting my son that I came to wonder whether my paints and the solvents I used to clean up after oil paints were completely safe. Looking back I wonder why it didn’t concern me more that I’d always get a headache when using artists’ white spirit in an unventilated room! When I started looking into it, I found that whilst information on the toxic effects of solvents is fairly compelling, hard data on the specific effects of paint pigments is nearly impossible to acquire. This is because the only research that has been done on is on people in factories or mines who are exposed to much larger doses of these substances and via airborne exposure.
So what exactly is the risk from these traditional heavy-metal pigments which still form a considerable part of an artist’s palette? And in the case of oil painting where the paint is traditionally diluted and cleaned with solvent-based spirits rather than water, should these substances should be avoided and what are the alternatives?
THE SAFETY OF PAINT PIGMENTS
What does your paint actually contain?
Trying to work out what is actually in your tube of paint isn’t straightforward. Manufacturers choose a marketing name for each paint colour they produce which does not tell you which pigment or pigments are actually contained within it. It’s easy to assume that the name on a paint tube and the pigment inside are one and the same, but this is rarely the case. Frequently paint companies will still name the paint shade after an old pigment that’s now become more or less obsolete due to lightfastness or toxicity concerns, even when the the paint contains a completely different pigment that has been substituted for the traditional one. A good example of this is vermilion, which originally came from a mercuric mineral called Cinnebar and later from a synthetically created mercuric sulphide compound.
Both these forms are highly toxic and true vermilion is now rarely sold, although the Michael Harding company does still produce the paint colour from that original pigment, complete with cautionary warnings about its potentially toxic effects. Most paint companies still carry a vermilion-like colour but they create it by substituting or mixing completely different pigments. When a manufacturer makes a colour mix to imitate a traditional single-pigment colour in this way the result is known as a ‘hue’ colour and they are supposed to label the paint as such.
Photo credit: jacksonsart.com
For example, Winsor & Newton sell a correctly named ‘Vermilion Hue’ in their ‘Winton’ oil paint range which they make from three quite different pigments. Other companies however fail to include the ‘hue’ description. Royal Talens’ ‘Van Gogh’ range includes a colour that they call Vermilion but which is actually made from pyrazolone orange and lithol rubine. Old Holland’s ‘Vermilion’ is really pyrazolo-quinazolone scarlet. I think it’s fairly obvious why Old Holland don’t think ‘pyrazolo-quinazolone scarlet’ is a useful marketing name: it doesn’t exactly trip off the tongue! But you can see how difficult it is even to identify which paint brands and their colours contain potentially toxic pigments.
The only place you’ll be able to find out which pigments are actually in a tube of paint is either on the manufacturer or retailer’s website, or a small code which will be printed somewhere on the paint tube that will start with the letter P for ‘pigment’ or occasionally ‘N’ for ‘natural’ pigment. Pyrazolone orange – for example – will be indicated with the code ‘PO34’. This code 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. Although these associations advise that best practise would be for the manufacturer to print the full name of the pigment as well as the index code, 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 index numbers on the front of the tube.
Having located your pigment number/s you can use this helpful website to look them up and find out which pigments are in your paint and what source they are derived from. Orange colours will begin with ‘PO’, reds with ‘PR’, greens with ‘PG’, and so on.
In both Europe and the USA paints must conform to standardized labeling systems alerting the consumer to any health or environmental hazards contained within. In the EU, they must conform to a regulation known as the ‘CLP’ which requires any ‘hazards’ to be indicated on packaging with a warning sign like one of these diamond shaped pictograms. You can find an explanation of the full meaning of these signs here.
The exclamation mark sign is considered a ‘warning’ mark and denotes hazards to health including eye, skin or respiratory irritation and being harmful if swallowed. The image with the figure indicates a ‘danger’ and lets you know that the hazardous content may be a carcinogen or may damage fertility, cause breathing difficulties, organ damage or genetic damage to an unborn child. It may also indicate that the product could be fatal if aspirated. You’re more likely to see these health-related warnings on a solvent-containing product such as white spirit than on a paint tube, although I have noticed the CLP ‘environmental hazard’ pictogram on a tube of Zinc White paint.
On the back of tubes of paint in both the US and Europe you’ll commonly 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). The ‘Approved Product’ designation certifies that the paint is non-toxic to both children and adults. If there’s a CL label then in the tube will also contain a specific written warning indicating detailing a caution, which will typically be that the paint may be harmful if swallowed.
Underneath the seals above you’ll notice that statement that the paint ‘Conforms to ASTM D 4236’. This relates to the American Society for Testing and Materials’ ‘Standard Practice for labeling Art Materials for Chronic Health Hazards’ which is a set of voluntary but universally adopted guidelines regarding health and safety labeling. It will typically be declared on every paint tube that might be sold in America, whether produced by a US manufacturer or one based elsewhere. This declaration doesn’t mean that the paint doesn’t contain any health hazard, it just means that any hazard will be clearly listed on the label. If the pigment within the tube is considered to carry any health risks then these will be stated in written form (for example ‘DO NOT SPRAY APPLY’). Finally, you may also see statements that conform to California’s strict regulatory laws such as ‘This product contains cadmium, a chemical known to the State of California to cause cancer by means of inhalation’
The evidence for heavy metal toxicity in paint
How should we interpret the various and contradictory warnings (or lack of warnings) about the heavy metallic pigments that some paint contains, and the differences between US and EU warnings? With lead white pigment the long accepted health concerns are universal and clearly well merited, although even so some artists still prefer it over safer modern white pigments like titanium and will seek out suppliers. Vermilion has also been more or less phased out with Michael Harding being the only UK supplier I can find for true lead white.
Even with vermilion however it is hard to assess the risks to the oil painter of long term use. There’s no doubt that cinnebar was responsible for the deaths of many who mined for it in centuries gone by and who inhaled a large quantity of it in powered form and and suffered from mercury poisoning as a result. However this is very different to using the pigment suspended within an oil and there’s no evidence that I can find that modern vermilion paint has caused health effects. It simply hasn’t been studied or tested at all and so there’s no way to know. Similarly although there is evidence that potters using powdered cobalt may have suffered from cobalt poisoning, there’s no evidence available that painting with pre-mixed cobalt paint has ever caused an artist to experience adverse health effects.
Whilst the use of true vermilion is now rare, cobalts and cadmiums are still commonly sold although some Japanese and American producers actively avoid them. For example Daniel Smith paints sell only cadmium ‘hues’. In the UK, Winsor & Newton have rechristened their hue colours within their professional oil painting range and sell ‘Cadmium-free Orange’ (for example) alongside their regular Cadmium Orange paint. As for the EU discussion on the safety of cadmium in artist’s paint, the proposal was originally raised by Sweden out of concern 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 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’.
In other words, as long as you don’t eat your paint, lick your paintbrush or use a pigment in the form of a powder or aerosol – possibly also in the form of a chalky pastel that may create dust – W&N are saying that the use of cadmiums in pre-prepared tube form is perfectly safe and I’m inclined to agree. The dispute will likely continue however. Some take the view that the stringent labelling on products intended for the US market is driven by the greater degree of litigation on that side of the Atlantic and that the warnings are a cover-all for very unlikely events such as a child getting hold of and consuming a large quantity of paint.
As Bruce MacEvoy points out: “ASTM guidelines require paints to be labeled toxic, or potential health hazards, if “in the opinion of a toxicologist” the pigment in the paint might produce “a chronic adverse health effect” as a result of any “reasonable foreseeable use or misuse” of the paints.” but these guidelines do not state what would quality as a chronic health effect, and precisely how this might be tested for by a toxicologist. Others are concerned that it’s precisely this lack of testing that means we should play it safe and avoid pigments such as cadmiums since there are alternatives on offer.
What about other pigment sources?
Not all paints use pigments from these inorganic mineral sources of course. Synthetic organic pigments (those ones with the names that do not trip off the tongue!) have been studied only in a very limited way and long term exposure to them in tube paint form has certainly not been examined. However they are not known to have any adverse health effects.
Common sense advice
Winsor & Newton’s general health and safety information page contains the following disclaimer:
“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 I’m personally happy to continute to use true cadmiums and true cobalts. I wouldn’t handle raw pigment in powder form and mix my own paints, but I think that with tube paint any health risks are probably non-existent and certainly dwarfed by that posed by the many chemicals people use around the house such as harsh cleaners, house paints, new synthetic carpets and so on. For pregnant women who naturally feel worried about taking the slightest risk, wearing gloves may alleviate concern.
SPIRITS USED FOR OIL PAINTING
It’s commonly said and is definitely true, that when it comes to health and safety in painting, the paints themselves are not really the problem. The pigments are not going to harm you unless they are actually air born, and in oil painting the linseed, safflower, poppy or walnut oils that they are safely bound with are absolutely harmless. The problem then, is what you use to thin the paint when you squeeze it out and how you clean up afterwards.
Because oil paints however are insoluble in water they require some kind of spirits to dilute and remove them from paintbrushes, palettes and your hands. It is possible to paint without any solvents, and some people choose to do so. However thinning your oil paint just with the addition of more oil will mean that you can’t achieve the thin, matte washes of colour that are desirable in an underlayer. Moreover in order to maintain the ‘fat over lean’ rule of oil painting, you don’t ideally want your underlayers to contain a very large oil content.
The problem with solvents is that they evaporate quickly, releasing toxins into the air. We’ll first look at some traditional solvents and then some low odor, safer alternatives and ways in which you could avoid using solvents altogether.
Note that any products mentioned here are impartial suggestions, and are not sponsored or paid in any way
Photo credit: jacksonart.com
Turps and white spirit
For centuries, the traditional solvent used by artists to thin their paint was turpentine. Turpentine is a solvent obtained by distilling resin harvested from living trees and like all solvents it emits Volatile Organic Compounds (VOCs) as it dries. Turps are still available and some artists still like to use turpentine for oil painting, but there’s no question that it can cause negative health effects including skin and eye irritation, nausea and headaches with quite a small degree of exposure. Long-term, large scale exposure has been linked convincingly linked to organ damage and neurological damage as well as an increased cancer risk.
Now that turps have fallen out of favour most artists use ‘artist’s’ white spirit which is a purified version of the more common white spirit used for DIY. Sometimes it is known as ‘mineral spirits’. White spirit frequently 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. Personally, working with white spirit always gives me a headache if I’m in an unventilated room and even if my exposure is much less than 8 hours a day, I just don’t think that this can be a good thing.
How to minimize your exposure when working with spirits
- 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.
- Keep your spirits either in the container that they came in,or in a glass jar. I wouldn’t pour them into anything else in case unless I was sure that the solvent couldn’t break it down.
- Keep a lid on your jar of solvents when you can, and always cover it overnight.
- Don’t paint in the room that you sleep in.
- Wash your hands well if you get solvents on your skin
Odorless mineral spirits (OMS) and citrus-derived turpentine
To avoid the unpleasant smell of solvents there are a number of odorless or low odor products such as ‘Sansodor’, a slow-evaporating, product made by Winsor & Newton which can be substituted for mineral spirits. It’s important to be clear that Sansodor 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 your health than white spirit just because it evaporates more slowly is unclear, and W&N does not make this specific claim. It’s much more pleasant to work with however as it barely smells and I find it doesn’t give me headaches. ‘Gamsol’ made by Gamblin is another option. 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’.
Photo credit: jacksonart.com
Another product worth considering is Winsor & Newton’s popular ‘Liquin’ range of mediums which are more viscose than spirits but not as glossy as an oil. Liquin does still contain solvents but as with Sansador and Gamsol they are slower to evaporate and aromatic particles have been 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 various products until you find one that you like.
Recently a number of products made from citrus plants have come onto the market, including ‘Zest-it’ solvent made by J and T Blackman and ‘Citrus Turpentine’ made by Wallace Seymour. Citrus based solvents are closer to turpentine than the petroleum based white spirit and are low-odor and supposedly less toxic. They can be used for thinning oil paint as well as as cleaning it.
Oil painting without solvents
- As we’ve mentioned, some people certainly do paint without any solvents, using oil (commonly walnut oil) to thin their paint for the lower layers. As long as each layer you apply has MORE oil than the first one, this will still obey the ‘fat over lean’ edict and your painting shouldn’t crack as it dries. You can read about the Fat over lean rule in this article on oil painting techniques.
- Another option would be to paint fairly thickly and in one layer (‘alla prima’) because then you’d only need a little additional oil to loosen your paint and it wouldn’t get overly glossy. You could also use an impasto medium to extend your paint and help it flow.
- You could switch to water-mixable oil paints, where you can thin your lower layers with some water as long as you also add a little oil to prevent the paint becoming over-thinned and ‘unbound’. Water soluble oil paints don’t actually contain any water in the tube. They work either with the inclusion of an additive which allows water molecules to bind with those of the oil binder, or by modifying a single molecule of that oil binder itself in order to make it able to make a solution with water. The drawback to thinning water-mixable oils with water is that they tend to change colour as they form the emulsion with the water, and then change back again as they dry. However if you are merely adding the water to lower layers which will eventually be covered over with paint mixed with extra oil, this may not be a problem. You can read more here about using water-mixable oil paint.
- You could choose to paint your lower layers in thinned acrylic paint. This is quite a common practice with some artists. So long as you always use the oil paint over the acrylic and not the other way around, mixing acrylics and oils is fine.
Here it really is possible to dispense with solvents altogether. Some people use detergent (washing-up liquid) which works quite effectively to remove oil paint from brushes and hands, but I avoid it out of concern about a residue being left that might contaminate future paint applications. It’s also pretty drying on the hands.
The US company General Pencil make some well-known and easy to source products called ‘The Master’s Soap and Brush Cleaner’ and ‘Brush Cleaner and Preserver’ which work very well. Their ingredients are a proprietary secret but are non-toxic and probably vegetable oil-based. Da Vinci also makes a ‘Professional Brush soap’ derived from vegetable oils. Any oil based product can remove oil paint and some people simply use walnut oil. There are also many oil and oil-based soaps which are marketed for brush and hand cleaning, including olive oil soap made by Chelsea Classical Studio. You could also pick up an olive oil soap in a health food store.
For the serious oil painter who does a lot of brush cleaning, Jacksons make big tubs of ‘Marseille Soap Pellets’ which are made from palm, coconut and soya oils. You mix them with water to create the amount and consistency that you want. It’s also worth mentioning Weber’s ‘Odorless Turpenoid’ products which get great reviews for washing brushes. This is an petrolium-based but odorless turpentine substitute containing no harmful aromatic compounds.