Water-mixable oils can be a friendlier option when painting at home.
If you are an oil painter who has temporarily moved your studio into your home, you may wish to try painting with water-mixable oils, which may be a safer alternative for the home environment.
There are many reasons to consider using water-mixable oils (WMO) at home instead of using paints with solvents:
- you share your space with children or pets
- you are worried about fumes from traditional hydrocarbon solvents (turpentine, white spirits, Zest-it, Shellsol T, odourless mineral spirits, etc) entering your living space
- you don’t have good ventilation
- you are sensitive to solvents (allergies have greatly increased in recent years)
- you dislike the smell of solvents
- they clean off clothes with just soap and water while still wet
They are also great for:
- plein air artists who are then able to clean up with just water
- taking on holiday as you don’t need to take combustible solvents on a plane
- if you have school or uni regulations to meet
Ten Key Things About Water-Mixable Oils
- Water-mixable oils are a friendly alternative to conventional oil paints when painting at home as you needn’t use traditional solvents to thin the paints or clean up – this means no fumes in your living space.
- Water-mixable oils are best used with painting mediums and not mixed with water, use water just to clean up afterwards.
- They could be called water-washable oils.
- There are mediums for extending, thickening, thinning, glazing, drying faster and water-mixable linseed or safflower oil which would be your slow-drying medium. It takes very little medium to make the paint flow.
- We stock seven brands of water-mixable oils and they vary in how soft they are out of the tube, how easily they dissolve in water, how much they seize up with water on the palette, how long they take to dry, if they dry matt or gloss and if they stay a bit tacky after they are dry.
- Schmincke Medium W is a great medium for making any oil paint into water-mixable oil paint. It is also great for making glazes and dries glossy without being tacky.
- Water is the solvent for these paints and you can use it for thin washy underpaintings that give a lean lower layer for layered paintings that observe the fat-over-lean principle.
- If you are dipping your brush into water while painting or leaving them soaking in water, hog bristles get waterlogged and soft, so it is best to use a synthetic hair brush with good spring – Jackson’s Akoya is a good choice for water-mixable oils.
- Water-mixable oils are real oils – so if you paint in layers you should observe the fat-over-lean rule by adding more medium to each successive layer.
- Because they are real oils they should be allowed to dry for six months and then they should be varnished with any picture varnish – this will remove any tackiness and add gloss.
Think of Them as Water-washable Oils
I know many artists who tried water-mixable oils once and didn’t like them. I have heard complaints that they are ‘sticky’ or ‘gummy’ and for some it’s been enough to give up on them altogether. Some painters love them – and most of these find it best to use painting mediums to make the paint more fluid and only use water to clean up, to not add any water to the paint or at least not to mix water with the paint on the palette. When used like this they work well and could be called water-washable oils.
Actually, there is no need to add water into the paint while you are working. Water is best only used when washing the paint away at the end of your session. In fact, mixing a small amount of water in with the paint on the palette can cause some brands to seize up pretty quickly as the water evaporates from the paint puddle on the palette and feels like it has started to dry. The amount that it stiffens varies by brand from a little sticky to quite stiff. If you paint with WMOs without adding anything or extend them with water-mixable mediums and not with water, it is similar to painting with conventional oils but afterwards, you can clean up easily with just soap and water.
Skip to the test results and chart of brand characteristics.
Table of Contents
- How Best to Use Them
- Four Ways to Paint with Water-mixable Oils
- Comparing the Makes of Water Mixable Oils
- Characteristics of the Different Brands of Water-mixable Oils
- Conclusions of the Testing
- Brushes for Painting with Water-Mixable Oils
- Brush Washing
- What Water-mixable Oils are Made of
- Are Water-mixable Oils Archivally Sound?
- Water Mixable Oils Have Many Things in Common With Regular Oils
- The Fat-over-lean Rule and Water-mixable Oils
- Links to the Materials at Jackson’s
How Best to Use Them and the Differences Between the Brands
There are two problems reported with WMO: stickiness or stiffness during painting and tackiness after drying. If you thin the paint with just a small amount of water, some brands seize up and become stiff and you can’t drag the paint off the palette. It seems like the paint has dried in just a minute, but of course it hasn’t. It’s possible that the additive for making it water-mixable has separated out and risen to the surface. Whatever the cause, it is frustrating to not be able to pick up the paint from the palette. Even the ones that are least sensitive to water will thicken as the water quickly evaporates off the palette. Think of water as the turps for these oils, except that it evaporates so quickly it causes this seizing-up on the palette after just a minute or so. The amount of seizing-up varies by brand, with Grumbacher Max, Jackson’s Aqua and Holbein Duo Aqua going the stiffest and Daler-Rowney Georgian Water Mixable barely going stiff at all. It is difficult to use when it has gone gummy or hard, it is not buttery and blendable like you want oil paint to be. I found that you can add water without it going hard if you add a lot, stir it well and use it for washes that look like oil paint thinned with lots of turps. There are ways to paint that avoid the stiff paint problem and I will go over those next. The second problem painters experience with WMO is what I call tackiness. After the water evaporates from the painting and it cures for 6 months to a year like a traditional oil painting, sometimes it stays tacky. I wanted to see how much of a problem it was and if they all did it.
We stock seven brands of water-mixable oils and they vary in how soft they are out of the tube, how easily they dissolve in water, how much they seize up with water on the palette, how long they take to dry, if they dry matt or gloss and if they stay a bit tacky after they are dry. We also stock Schmincke Medium W, which is added to conventional oil paint to make any paint water mixable. I wanted to see how these 8 paints differed.
Four Ways to Paint with Water-mixable Oils Without Adding Water on the Palette
Remember that since they are oil paint you need to paint on a sealed, primed surface just like for conventional oil paint. Universal primed canvas or an acrylic gesso is best if you are using any water in your paint. Do not use an oil primed surface as these paints mixed with water will bead up.
Using just paint
You can paint with the colour neat, just paint, mixed on your palette with no water or mediums.
All the brands are workable from the tube, some are softer and some stiffer, and the softer ones are easier to use neat. Even the soft ones do not have the same amount of spread as regular oils unless you add a medium to allow them to be brushed further, but if you work in an impasto style this should be fine. You can only do this if you are painting alla prima – either in one sitting or in a couple of days if no part dries while you are still painting – because without adding a thinner to make the first layers lean and adding more oil to the later layers you would not be creating a stable fat-over-lean structure.
Wet brush blending
Using a wet brush on the canvas – but not on the palette.
If you find while using the paint neat that it’s not flowing enough on the canvas – then dipping your brush in water, a water & medium mixture, or medium – and using it on the paint that you already have on your painting can make the paint flow and not cause the problem you get with adding water to the paint on a palette, where it seizes up and becomes hard to pick up off the palette. It allows you to spread the paint further on the painting. A mixture of water and water-mixable medium will turn milky white and may temporarily lighten the colour of the paint until the water evaporates – this colour shift may or may not affect how you paint. You can start with 50:50 water and medium and increase the amount of medium in the water for successive layers to comply with the fat-over-lean rule.
Using a lot of water like turpentine to create a wash
Because not all of the water can evaporate quickly it doesn’t get stiff like it does when you add just a little water. You create a washy puddle of paint with lots of water on your palette. Water is the solvent for these paints. It acts like turps does in regular oils, it thins the paint, makes the paint leaner, and then evaporates. Used this way you would paint with lots of water for an underpainting (the first layer on the canvas) or for making paintings that look like watercolours. It is very matt just like a turpentine wash, because the oil layer is now very thin, and it is the oil that is the shiny part. Mix a lot of water into your paint on the palette until it is smooth. This could be useful for a lean underpainting in a layered painting, to obey the fat-over-lean rule. Adding some water-mixable medium to the water will give you some binder to make a more stable film. Your puddle will eventually stiffen when the water evaporates so it is good to use it all before then.
Any oil medium – water-mixable (or conventional if used less than 30% to keep the paints water mixable) – can be dipped into or mixed in on the palette. There are mediums for extending, thickening, thinning, glazing, drying faster and water-mixable linseed or safflower oil which would be your slow-drying medium. They increase the gloss of the paint. One drop of water, even before it seized up, does not make these paints flow as well as one drop of medium, which made the paint go twice as far. Many water-mixable oil painters like to use M Graham Walnut Alkyd Medium, which is not a water-mixable medium, but if you use a small amount it doesn’t interfere with the water-washability. It is very fluid and the label on the Walnut Alkyd Medium advises to use it sparingly anyway to avoid beading up – “3 to 9 drops of medium to 1 inch of colour”. The WMO mediums vary a lot, some smell very strong of bitter chemicals and some smell like nutty linseed. Some of the water-mixable mediums contain water.
In my tests so far the different brands of the water-soluble oil painting mediums work fine with all other brands of water-soluble paints, you don’t need to stick with the same brand of paint and medium. They vary a little in how easily they wash out of the brush with water. I will do a separate post looking at the mediums.
All four methods
I used all four methods and found I could paint as normal and I almost forgot that it was not conventional oil. Until I went to clean up and realised how easy it was to wash my brushes, palette and any I got on my hands, and that my clothes and room didn’t stink. My sink wasn’t ringed in oil paint tide marks. I realised the next day that I had got some on my clothes, and as it was still wet it washed off completely with just water and a bit of bar soap. I would normally have used Zest-it on a rag while wearing nitrile gloves and even if it was a small area the clothes would still reek of chemicals after four cycles of the washing machine. So this was truly wonderful!
Comparing the Makes of Water Mixable Oils
Prices and range of colours
At Jackson’s, we stock seven makes of water-mixable oil colour. The prices shown give an idea of how the prices of the ranges relate to each other. The prices will change in time, so these are only accurate right now. Since there are different size tubes, I’ve done the maths to show the price per ml. Note the fantastic value of Jackson’s Aqua Oils. I’ve arranged them in descending order from artist to student grade and added the Medium W at the end.
- Daniel Smith Water Soluble Oil Colour
6 series £8.90-£31
Series 1 price per ml = 24p
43 colours in 37ml, White in 150ml
- Grumbacher Max Water Mixable Oil
6 series £9-£27
Series 1 price per ml = 24p
59 colours in 37ml, White in 150ml
- Holbein Duo Aqua Oil
6 series £9.10-£37
Series 1 price per ml = 22p
80 colours in 40ml which includes 6 non-lightfast fluorescent colours, Whites in 50ml and 110ml, plus sets
17 additional colours in their Elite range with heavy metal pigments like cadmium and cobalt
(They are the only brand that claims they can be mixed with watercolours, I didn’t test this.)
- Talens Cobra Artist Water Mixable Oil
4 series £4.20-£10.70
Series 1 price per ml = 10p
70 colours in 40ml, Whites in 150ml, plus sets
They also have a student range called ‘Cobra Study’, that we do not stock.
- Jackson’s Artist Aqua Oil
3 series £3.50-£4.60
Series 1 price per ml = 6p
48 colours in 56ml, White in 225ml
- Winsor & Newton Artisan Water Mixable Oil Colour
2 series £4.30-£5.40
Series 1 price per ml = 12p
40 colours in 37ml, 30 colours in 200ml, plus sets
Winsor & Newton consider it to be between an artist and student range.
- Daler-Rowney Georgian Water Mixable Oil
1 series £13.60-£31 for sets
Currently, we only do these in sets of 20ml or 37ml tubes
Series 1 price per ml = 8p
- Schmincke Medium W
Added to conventional oil paint to make it water-mixable, 1 part medium to 2 parts oil paint.
Medium W in 60ml & 200ml, Medium W Gel in 35ml & 120ml
Artist and Student grades
A paint range can be considered a student range if it has:
1. Only one or two price series. Because they use hues and cheaper pigments with none or few of the expensive pigments like genuine cadmium or cobalt.
2. A smaller colour range.
3. Fewer single pigment colours (this is related to having lots of hues, which are mixed colours, as well as having more convenience mixes for learners).
4. Additives to speed drying or to adjust the paint so all the colours dry in the same amount of time.
5. Additives to bulk out the paint like Magnesium Carbonate, which can over the years react with air to make any oil paint unstable. More additives might also mean that there are particles interfering with the linking up of the oil molecules to create a hard film, so they only dry moderately hard.
6. A lower pigment load, which makes it weaker in colour.
Comparing the WMO Paints
In order to compare the WMOs I identified the following attributes as a measure of quality:
1. A smooth, buttery application like traditional oil paints.
2. Strong, rich colours like traditional oil paints.
3. Stays open long enough for blending like traditional oil paints.
4. Archivally sound – no cracking, peeling, fading (if used in a normal manner).
5. No solvent fumes.
6. Easy cleanup.
The tests I did
I painted out swatches of Alizarin Crimson in all the brands and made the observations that follow. Note that these observations are just for this one colour. I also did a pigment load test and water tests with Ultramarine Blue. All tests and charts were done with the brands in the same order.
The Colours I Tested in the 7 WMOs and one conventional oil
They each used a variety of pigments for their Alizarin Crimson or Alizarin Crimson Hue. Ther are a variety of price series as well.
Daniel Smith – PR177 Series 3
Grumbacher Max – PR83 Series 3
Holbein Duo Aqua – PR83 Series B
Cobra Artist – PR264 Series 2 (Madder Lake, they don’t have an Alizarin, but since Alizarin was originally created as an improved Madder it is similar)
Jackson’s Aqua – PR177 Series 2
Winsor & Newton Artisan – PV19 Series 1
Daler-Rowney Georgian – PR177 No series
Michael Harding (traditional oil) – PR83
Michael Harding mixed with Schmincke Medium W
All the brands used PB29 for their Ultramarine Blue.
The seven makes of water-mixable oils, plus a conventional oil, and a conventional oil with Schmincke Medium W added.
The swatches were 1. a large blob to leave on the palette, 2. spread with palette knife thick and thin, 3. brushed on thick and thin, 4. mixed with 3 drops of water, 5. mixed with 3 drops of Holbein Duo Aqua Painting Medium 6. A thin scraping with a palette knife 7. then washed out from there with a wet brush.
With just the seven WMO – 1. neat, 2. with 1 drop of water, 3. with one drop of Holbein Duo Aqua Painting Medium 4. mixed with 20% Holbein Duo Aqua Titanium White. The Mixing with white was to test the colour strength but also showed that the white might have driers cos they all dried quickly when mixed with the white.
Characteristics of the Different Brands of Water-mixable Oils
Softest to stiffest in Alizarin Crimson
Conventional oil mixed with Schmincke Medium W (very soft, almost fluid. The Medium W Gel would be thicker)
Daler Rowney Georgian (very soft, also separated a bit) Easiest to use neat – no water or medium – because it is so soft.
Daniel Smith (buttery)
Cobra Artist (buttery)
Grumbacher Max (buttery)
Jacksons Aqua (buttery)
Winsor & Newton Artisan (buttery)
Holbein Duo Aqua (slightly stiffer but still buttery)
Odour is minimal with all brands. Any odour is going to come from the mediums you use, which vary a lot in odour – some WMO mediums have a strong chemically smell and some have a mild nutty linseed smell. I will do a separate article about the WMO mediums.
Dissolving in water
They all easily dissolved in a puddle of water with the exception of Grumbacher Max which needed extra stirring. Cobra was the best at using water as a thinner, it spread the farthest. Georgian and Cobra seized up the least on the palette when mixed with a small amount of water.
Stiffening when mixed with a small amount of water on the palette
The mixing puddle on the palette will stiffen when mixed with a small amount of water in most brands and it’s hard to pick the colour up with your brush. WMO that has been mixed with any amount of water will become sticky on the palette as the water evaporates, but is most noticeable with a small amount of water because it evaporates in seconds. After the water has left the ones that had gone stiff do not revert back to how they came out of the tube, they are changed. If you mix a lot of water in and use it as a wash it is easier to handle but any left on the palette will later be stiff after the water evaporates. The stiffest swatches on the palette were Holbein, Jackson’s, Artisan and Max. Daniel Smith thickened up some. Cobra, Georgian and Medium W were almost unaffected. But this effect isn’t as important as I originally thought it would be, because the best way to paint with these is using medium and not water, which they are all good at.
If the background is a watery wash, and an object is painted on top, then the blending of edges to create a soft edge is difficult as the water wash had already gone stiff or touch dry in 10 minutes. So it seems that the stiffening on the palette also works on the painting and you won’t be able to count on blending with previous paint if it contains water or is a thin layer.
Mixing into medium
They all mixed easily into a glaze medium.
One drop of water, even before it seized up, did not allow the paint to flow as well as one drop of medium, which made the paint go twice as far.
The mediums come in relatively small bottles because it takes very little to make the paint flow and the three I tested all reduced the tackiness of the dry paint while keeping or increasing the shine.
Max benefited the most from a medium – it dried faster, painted on smoothly and stayed shiny without becoming tacky.
Cobra, Jackson’s and Artisan all retained their satin sheen but lost all their tackiness when mixed with Cobra Painting Medium.
I tested two ways – mixing with 20% Duo Aqua Titanium White and mixing with 80% Duo Aqua Linseed Oil. It was not perfectly measured but I took pains to get similar amounts of paint and used a pipette for the liquids.
Daniel Smith has a much higher pigment load than the others, comparable to the Michael Harding conventional oil in the Alizarin Crimson and Jackson’s Artist in the Ultramarine Blue.
Of the rest, Artisan, Jackson’s, and Max had more pigment than the other three – Holbein, Cobra, and Georgian.
Remember that Crimson is a naturally very slow drying pigment.
Grumbacher Max, Holbein Duo Aqua and the Schmincke Medium W do not seem to have driers added – they stayed open longer than the other five. The slowest drier by far was Max, the crimson brushed on neat was still wet 20 days later. Holbein and Medium W were 9 days. But remember that Crimson is a very slow drying colour. Daniel Smith, Cobra Artist, Jackson’s Aqua, Artisan and Georgian do have driers added – they dried much more quickly. Daniel Smith may not have as much of the driers added because although the thin swatch dried as fast as the others with driers added, the thick swatch and the blob on the palette didn’t skin over as fast as the others with added driers. The Holbein might have added driers in the Titanium White colour because all the colours mixed with it dried very quickly. In some paint ranges driers are added to slow-drying colours to even-out the range so all the colours dry at the same rate.
In all except the Grumbacher Max and Medium W, a very watery wash was touch-dry in 24 hours. The traditional oil in a turpentine wash was not touch-dry in 24 hours either, it took 5 days.
The blob of paint still wet on the palette.
After 10 days all seven WMO, the traditional oil and the Medium W were all still wet on the palette, though the Cobra, Jackson’s, Artisan and Georgian were partially skinned over. The four fast-drying WMOs start to skin over on the palette in a day or two, even if you have not added water. I have read that some artists keep them wet by misting them with water and then putting the palette in a palette box or some similar setup.
Surface sheen after drying
Artists sometimes mention the WMOs dry dull but I did not experience this. They may have been referring to the slight colour shift if using milky water and oil as a medium, which does occur – the colour dries a bit darker as the white emulsion becomes clear. Or they may have meant that the surface dries matt, which may look duller until it is varnished. The paints that dried more matt after they had been mixed with water – I found that if I touched or rubbed the surface it became gloss, like perhaps the matt effect is a residue on the surface. I wasn’t able to find out anything about this except that the emulsion and volatiles are meant to release, so perhaps that is what this is.
All except Daniel Smith, Georgian and Medium W dried matt when mixed with any amount of water, these three stayed very glossy. (Daniel Smith and Georgian also stayed quite tacky, see below.) They all dried glossy when mixed with the painting medium except for Artisan, which dried almost matt. Jackson’s and Artisan dried satin when used neat, the rest dried more glossy when used neat.
It is important to remember that the sheen can be adjusted with varnish after the painting is fully dry in six months to a year and with a re-touching varnish in the meantime. It doesn’t need to be a WMO varnish, at this point the painting can be treated as a regular oil painting. All oil paintings should be varnished to protect the surface and to seal it so it stops absorbing oxygen when it is stable enough. So if you are going to be varnishing it with a gloss varnish anyway, then there is no real concern about the sheen of the paint, and varnish will add any wet-look richness that is missing. Additionally, the matt surface of the paint is an advantage during the drying period because the paint isn’t tacky, so won’t attract dust while it is in the studio.
Tackiness after the painting has dried
There are theories that suggest the tackiness of some paints might be the emulsifier migrating to the surface, or that the painting mediums leave a tacky residue. However, I found that during my testing the 3 mediums I used lowered the tackiness.
All the paints that dried glossy stayed tacky after they were touch-dry except the Medium W (see below). Whatever is making them shiny is also keeping them a bit sticky, so the ones that tested the shiniest are also the ones that dry tackiest. You should varnish oil paintings for protection after they are fully dry anyway and that will stop any tackiness as varnish is hard and not tacky. But the matt surface of some of the paints could be an advantage during the drying period because the surface of those paintings isn’t tacky, so won’t attract dust while it is in the studio waiting to be varnished. See the Surface Sheen section above for a bit more about varnishing.
The amazing exception to the glossy = tacky finding was the Schmincke Medium W mixed with Michael Harding oil colour. It was the second shiniest paint mixture and it was not tacky after it was dry. It makes a lovely mixture for jewel-like glazes. I tried the regular thin version, they also do a thicker gel.
The best way to use these paints is to avoid using water and only use mediums to extend the paint because water changes the paint to being stiff either quickly or after a few minutes and it doesn’t spread very far. It takes a very little medium to extend the paint and the mediums also even out the drying times and reduce the tackiness. Any problems with the dried painting being dull, matt or tacky can be solved with a final varnish, which you should do on an oil painting anyway, so these characteristics do not need to be taken into consideration, except that a tacky painting will need to be protected from dust while it is waiting the full 6 months to dry or you could apply a retouching varnish as soon as it is touch-dry. This leaves as the main characteristics for choosing between brands: price, pigment load, and if you are using them neat, texture.
I often recommend that a good way to figure out which brand you prefer is to get each colour that you need in a different brand. Then as you use them up, replace that colour with the brand you now know you prefer. Many artists have some colours they like in one brand and some in another so they use a mix of brands.
Daniel Smith – The stand-out for pigment load, much stronger than all the other brands. Moderately fast-drying, fairly buttery, not too stiff if you do use water. Dries glossy and stays a bit tacky, so will need protection from dust until it can be varnished.
Grumbacher Max – Best used with a medium and then it does very well. Very slow drying, so it’s good for painting with gaps of days when you can’t paint, but you want to get back to a wet painting that still blends. Using a painting medium will speed up the drying a lot. Has a medium pigment load, fairly buttery. Avoid using with water as it goes very stiff. Sometimes takes an extra soaping to get brushes clean. Satin sheen when dry and not too tacky.
Holbein Duo Aqua – One of the three that cleaned out of the brush the easiest. The largest range of colour and has separated the more toxic pigments into a separate line of colours the ‘Elite’. Not a very high pigment load in the two colours I tested. Satin sheen when dry and not too tacky. Buttery, but slightly stiffer than some of the others.
Cobra Artist – Not a very high pigment load in the two colours I tested. Satin sheen when dry and not too tacky. Fast-drying.
Jacksons Aqua – Moderate pigment load, better than some of the others. Satin/matt sheen when dry and not too tacky. Buttery, but slightly stiffer than some of the others. Cleaned out of the brush the easiest, even when a medium was used. The formula seems to have changed since I last tested it. It seems like they have added a filler powder to thicken it and keep it from separating in the tube. This has made the paint more paste-like, the colour less vibrant, and reduced the transparency of transparent colours.
Winsor & Newton Artisan – Moderate pigment load, better than some of the others. One of the three that cleaned out of the brush the easiest. Satin/matt sheen when dry and not tacky.
Daler-Rowney Georgian Watermixable – The extra soft texture makes this a good choice for painting neat. Not a very high pigment load in the two colours I tested. Dries quickly. Works the best with only water. Dries very shiny and stays very tacky, so will need protection from dust until it can be varnished.
Michael Harding (conventional oil) – A high pigment load, buttery textured conventional oil.
Schmincke Medium W – Acts as an extender medium to create great flow, gives you the pigment load of the conventional oil you choose to use, so it can have the highest pigment load. It adds transparency so it is not best for painting opaquely but is great for glazing. It stayed open a long time, it blended and mixed in easily and smoothly, it seized up least with water, it remained shiny and was the only glossy paint that wasn’t tacky when dry. Cleaned up with water very easily. It uses alkyd resin but isn’t fast-drying, which is unusual. It is available in a fluid and a gel. This is now a favourite medium that I will use in my conventional oil painting – it’s really beautiful and will make things easier to clean up.
Click the chart to see a larger version.
Brushes for Painting with Water-Mixable Oils
Since you will be dipping your brushes in water to rinse them between colours and you may paint with water or a water-oil mixture, you will get better performance from a synthetic-hair brush. Hog bristle brushes tend to get water-logged and soft. The paint also gets stickier using a hog brush, it must absorb something from the mixture. Jackson’s Akoya Brushes are a great choice. They also work great for painting in traditional oils.
Final Brush Washing and Brush Rinsing Between Colours
Washing up liquid works for washing your brushes, but if you have let them start to dry, got paint worked deeply into the hairs, or have used a medium then you will probably need a good brush cleaning soap. I use Jackson’s Marseille Soap for most brush cleaning. It is very good and very economical. You get a big bucket half full of soap pellets – simply pour the pellets out, fill it halfway with boiling water and slowly pour the pellets back in while stirring constantly. A wire whisk works well (it won’t contaminate your kitchen whisk). Get it all stirred in before it cools in a couple of minutes, it gets quite thick near the end of the stirring, it will look lumpy, that’s ok. Let it cool for 20 minutes and its ready to use. Rub your wet brushes on the hard soap in the bucket. It will last for ages. I use a Brush Egg to save my palm and the palm of my glove. For stubborn brushes that aren’t coming all the way clean the best soap is Masters Brush Cleaner. I also like Chelsea Classical Lavender Soap.
I found that Jackson’s Aqua cleaned the easiest of all the WMO paints, even when a medium was used. The Holbein and the Artisan were the next easiest to clean out of brushes. The Max took a few soapings.
When changing colours, most brushes rinse out in water similarly to rinsing conventional oil paint on a brush in turpentine. Pressing on the bottom of the water container and bouncing the brush helped to remove enough of the colour while painting. Grumbacher Max was the least easy to rinse in plain water.
What Water-mixable Oils are Made of
Water-mixable oil colours (WMO) were first marketed for artists about thirty years ago. They are also called water-soluble, water-miscible, water-reducible and aqua oils. There is no water in the paints in the tube, but instead of repelling water, these oil paints can mix with it. There are a few ways to allow the oil and water to mix and each brand uses one of these or a combination. They may use modified linseed oil where a fatty acid molecule in the oil has been altered to bind with water instead of repelling it or the molecule has been removed or it has been coated with a surfactant. The other option is to add an emulsifier to the oil. Like all emulsifiers it allows water and oil to mix because one end of the molecule attracts oil and the other end attracts water, so it holds them together. For example, egg is an emulsifier in both egg tempera paints and mayonnaise. Most brands have added driers. Some may have added fillers to bulk out the paint.
A painting made with WMO cannot be reactivated with water after it has dried because they are oil paints and when they are dry they are hard like any oil paint. Water has evaporated long before the oil paint forms a film, so no water is trapped inside. There is good enough science behind these paints that now over 12 major paint manufacturers make a water-mixable oil.
Knowing a bit about what they contain didn’t help me predict which would react quickly or strongly to water and which had a mild reaction. But I asked the brands for some information and this is what they told me. Daniel Smith uses modified linseed oil. Grumbacher Max uses an emulsifier, a polyoxyethylene (POE) sorbitol hexaoleate derivative. Holbein Duo Aqua modify their linseed oil by coating the molecules with a proprietary surfactant and do not use amine soaps or emulsifiers. Artisan uses linseed and safflower oils that have been modified with an emulsion. Georgian uses a blend of modified linseed (non-white colours) and sunflower (whites) oils and emulsifying agents. Schmincke Medium W uses a modified alkyd resin.
Artisan was one of the first big brands to make these paints. Historically Artisan was the brand most complained about for both stickiness while painting and tackiness after drying. More recently I have heard this is not a problem any more, so they must have changed their formulation. It is now satin-matt and the least tacky of the ones I tested. Artisan acknowledged that they have “probably made adjustments to the formula over the years to improve its use”.
Are Water-mixable Oils Archivally Sound?
Because these paints are relatively new, artists are understandably concerned about their longevity. Dried WMOs are waterproof like traditional oils and they use lightfast pigments like in traditional oils. There isn’t complete information available about what all the makers use as their emulsifier or if any altering of the fatty acids reduces the overall polymerisation of the oil paint. One study says some or all of the emulsifiers are volatile, so they evaporate before the oil needs to begin its long drying process. This means that after any water evaporates (quickly), then the added emulsifier evaporates (fairly quickly), then the drying oil begins the long, slow process of absorbing oxygen to harden (linseed oil is a drying oil because it can absorb oxygen) which may take six months or more. A few studies have been done that tested the hardness of the paint film. In the two brands tested, the water-mixable oils were at least as durable as traditional student-grade oils like Winton, Georgian, and Van Gogh oils. Because student-grade oils have fillers that interfere slightly with the oil forming the cross-linked bonds that make it hard, they were comparable with the two WMOs tested, either because of fillers, emulsifiers or modified oil.
Water Mixable Oils Have Many Things in Common With Regular Oils
Like conventional oils, water-soluble oils are made with linseed oil and pigment (but the linseed oil has been modified or an emulsifier added). If water is used while painting then water-mixable oils dry in two stages: the water evaporates and then what is left is similar to conventional oils and dries by oxidation at a similar rate to conventional oils, touch-dry in three to nine days. Just like conventional oils you still need to remember the fat-over-lean rule, you still need to let the painting dry completely (often 6 months to a year) before you varnish with regular picture varnish for protection, you cannot mix it with acrylic, you cannot paint acrylic on top of it but you can paint it over dried acrylic. You can mix aqua oils with regular oils or regular oil mediums but as you add more conventional oil you will lose the ability to clean up with just water. If you keep the conventional oil paint or mediums to under 30% you should still be able to clean up with soap and water. The paints are all inter-mixable with other brands.
The Fat-over-lean Rule and Water-mixable Oils
If you paint in layers and you let each layer dry before you paint the next one (dry enough so that the next layer does not mix with the previous layer) then it is important to obey the principle of fat-over-lean. Having each layer be more oily than the last means the top layers dry slower and are more elastic than the lower layers. This will ensure that your painting doesn’t crack later. There are two ways to follow the rule using water-mixable paint if you paint in layers. You can thin with water and add less water to each layer with the last top layer being neat paint. Or you can use the mediums to increase the oil content in the paints. Or you can make a mixture of water-mixable oil medium and water and for each layer increase the oil in the water mixture. Because a glaze is the last layer of paint a glazing medium is very high in fat.
You can also avoid solvents with traditional oils by using linseed oil to loosen the paint and to clean brushes. But be aware that adding more oil will slow drying and you may have a hard time continuing to add oil for the fat-over-lean rule if you paint in layers. Using alkyd mediums can help with this but you will need to wash your brushes straight away as alkyd medium can be hard to clean out of brushes without solvent if it has started to dry.
Some artists use water-mixable oils for mono printing, alone or in mixed media paintings with watercolours. A small amount of gum Arabic from the watercolours should not interfere with the oil paint, gum Arabic is an ingredient in some oil painting mediums. But be aware that you will still need a surface suitable for oil painting, so if using paper you will need an oil painting paper or to prime your paper.
More Water Mixable Oil Painting Articles on the Blog
- How to Start Painting with Cobra Watermixable Oils
- Max Hale Reviews Cobra Water-Mixable Oil Colour
- Jackson’s Akoya – the Best Brushes Going for Oil, Water-mixable Oil or Acrylic
- Daniel Smith Water Soluble Oil Paint
- Cobra Water-mixable Oil Painting Mediums
- Make Your Favourite Oil Colour into a Watermixable Oil Colour
- Watermixable Oil Colour Drying Times
- Cobra Water Mixable Oils
- Trying Schmincke ‘Medium W’ for Oil Colour
References and to read more
Modern Paints Uncovered The article is The Performance and Properties of Artisan Water Mixable Oil Colour Compared with Other Oil-Based Paints by Winsor & Newton (pp 53-57).
Links to the materials at Jackson’s
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