The Oil Painting Medium Nobody Fully Explains

If you’ve been searching for less toxic mediums to use with traditional oil paints, you may have come across a mysterious product by Schmincke, ‘Medium-W’.

It sounds more like a character from a Bond film than an artist’s medium, but it’s actually quite an ingenious solution for turning traditional oil paints into water-mixable ones.

Seems like magic?

In this guide, we’ll look at what Medium-W actually is, what it does to the handling of your paint, how much to add, the difference between the fluid and gel versions, and if it’s the right medium for you.

What Is Medium-W?

Medium-W is a painting additive produced by Schmincke.

It’s a modified alkyd resin that’s been developed to transform traditional oil paints into water-mixable oils. It has been chemically adjusted to accept water into its structure, so instead of repelling water as conventional oils would, it can combine with and work alongside them.

The “W” stands for water, and at the moment I haven’t come across another manufacturer producing a product quite like this (if you have, let me know in the comments)

With traditional oils, you would typically use Turpentine or Odourless Mineral Spirits (OMS) to thin the paint. Medium-W offers an alternative approach for artists looking to reduce their reliance on more traditional solvents. By mixing the medium in with your oil paint, you can then use water as a way to dilute it further.

The Control

Here is some Old Holland traditional Oil paint. Old Holland is often thicker than other oil paints straight from the tube, so it will be a good paint to use when you’re adding another medium to dilute it.

Here, the Old Holland traditional oil paint is diluted with a small amount of Odourless Mineral Spirits. In this example, I’m using Gamsol from Gamblin.

Notice how the paint thins very easily and has smooth brushstrokes while still retaining a bit of texture. This is only with a small amount of OMS.

For experimental purposes only, I’ve also shown diluting the traditional oil paint with a small amount of water, and you can see how it’s kind of separating and not really holding a fluid film.

Mixing 2 Parts Oil Paint: 1 Part Medium-W Fluid – (Recommended amount by Schmincke)

I’ve mixed the recommended 2 parts oil paint to 1 part Medium W. I found the easiest way to do this was to put out 2 blobs of oil paint, then a third blob of Medium W (roughly 50%)

Then mixed well together with a palette knife.

The photo above shows it further diluted with water.

Adding Medium-W to your paint changes several properties at once, which is why it can feel quite different from simply thinning paint with a mineral spirit.

Medium-W loosens the paint’s consistency and improves its flow across the surface. It will also add a bit of body to the paint compared to diluting it with OMS alone.

The only drawback was that when I came to clean the brush with water, it still diluted it, but a lot of the oil paint was left in the bristles.

On the Schmincke website, it says, ‘if necessary, add more medium W,’ and I’ve found from experience that using it at a slightly higher ratio makes it easier to clean brushes and adds a nice flow to the paint.

Paint Film Integrity

I must point out at this stage that increasing the amount of Medium W works if you’re working alla prima.

If you’re working in layers, it adds a bit more complexity. The higher dilution is only recommended for the thin underpainting, always respecting the fat-over-lean approach.

If you are painting in thicker layers, keep your added medium W to the recommended ratio to preserve the structural integrity of the paint film.

Mixing 1 Part Fluid Medium-W: 1 Part Oil Paint

I’m now mixing 1 part Fluid Medium-W to 1 part oil paint, so they’re equal in volume.

I’m using a pipette to slowly add the medium to the paint, then thoroughly mixing everything together with a palette knife.

Here you can see the fluidity when fully mixed at a 1:1 ratio. Once mixed, the paint can be thinned further with water, and your brushes and palette can be cleaned with water as well.

Which brings us on to colour shift.

The Colour Shift Issue With Water

When traditional oils are mixed with Medium-W and then further thinned with water, you’ll often notice a visible colour shift between the wet and dry paint films. This shift is much more noticeable than when using a dedicated thinner or painting medium.

Colours dry lighter, flatter, and less saturated than they initially appear when first applied.

While wet, the paint can sometimes appear slightly milky or cloudy before drying back clear. The darker the pigment colour and the higher the water ratio, the more noticeable this shift becomes.

So, although Medium-W can seem like a perfect solution for making your existing oils water-mixable, it also introduces another variable you need to learn to compensate for while painting.

Can you clean your brushes with water?

Kind of.

You can see above that I’m now cleaning out the brush, using the dilution of a 1:1  ratio. I’m then rinsing the brush in clean water to see how effectively the paint releases from the bristles.

At this ratio, it’s removed most of the pigment quite well.

This pink is quite a staining colour, so it’s giving me a bit more of a challenge.

What I’m going to do now is place the brush into some odourless mineral spirits to see if there’s any remaining pigment still trapped in the bristles that can be lifted out.

So on the right, you can see there was still some additional pigment left in the brush that I couldn’t fully remove with water alone. The odourless mineral spirits cut through the remaining oil residue a little more effectively.

Schmincke Medium-W Gel

Schmincke Medium-W comes in two forms: Gel and Fluid. They both do similar things in terms of the chemistry, but have different handling properties. The gel medium offers greater viscosity and a thicker starting point for diluting the paints, so you don’t get as fluid or runny a consistency.

Medium-W Fluid

This is the standard version, a pourable, liquid medium. It has the consistency of oil, and it integrates smoothly and quickly into paint on the palette. It’s best to give the bottle a shake (with the lid on!) before using it.

When to use it: Use Schmincke ‘Medium-W’ Fluid to improve the flow of your paint while reducing its body. Use for any passage where you’re painting in thin-to-mid layers.

Medium-W Gel

The gel version has the consistency of a soft, translucent gel. It doesn’t pour; you squeeze it out from the tube.

The gel form does everything the fluid form does but has more body. When you mix it into paint, it increases the paint’s viscosity while simultaneously making it more workable.

When to use it: Use Medium-W Gel when you’re after thicker marks, more textural, impasto-style effects.

If you’re trying to decide between the two, ask yourself what your paint needs to do:

• If you want paint to flow more easily and move smoothly, use the Fluid.
• If you want paint to hold its shape while becoming more responsive, use the Gel

2 parts paint: 1 part Gel

Here is the consistency of the paint when mixed: 2 parts traditional oil paint to 1 part Medium-W gel, mixed with a palette knife.

So the gel is probably the version I tend to lean towards, unless you’re going to be using very sketchy, loose painting. Personally, it gives me better consistency for the type of paintings I’d be working with.

Michael Harding’s Miracle Medium

Michael Harding Miracle Medium for traditional oils

“Derived from renewable vegetable sources, the Miracle Medium™ range is odourless, solvent-free, and designed to provide a safer, cleaner studio environment”

An alternative to working solvent-free and non-toxic with traditional oils is to use Michael Harding’s Miracle Medium.

I often use this in the studio, and you only need to add a small amount to increase flow and dilute the paint. You don’t get the same dramatic colour shift from wet to dry as you do when thinning heavily with water.

The drawback of this medium is that the recommended ratio for adding to your traditional oil paints is only 5 to 10%. This means you can’t really achieve a thin consistency for underpainting as you could with Odourless Mineral Spirit.

Also, it takes longer to dry than using Odourless Mineral Spirit.

A solvent-free alternative to the medium W gel is solvent-free gel from Gamblin

You can also get solvent-free alternatives for traditional oil gels, like this one from Gamblin.

Can you use linseed oil with the Medium-W

No. The linseed oil will work against the water-mixability you’ve added with the gel/fluid.

Can I use water-mixable Linseed Oil with Medium-W

Yes, you can; the water-mixable linseed oil will mix well and is easier to clean when washed with water.

How do Water-mixable Oils compare?

Here I’ve poured out a small amount of Pyrrole Red from Cobra water-mixable oils, and then I’m going to dilute it with a touch of water (about the same amount of OMS that I put in the first control dilution)

You can see the flowing paint, just diluted with a dash of water, and it’s got a nice even consistency. Personally, I much prefer using a water-mixable thinner or medium instead of water.

Thinning heavily with water can still introduce some of the wet-to-dry colour shift issues discussed earlier, so there are always a few technical variables to learn and work around.

Winsor & Newton water mixable oils thinner. I often use this when working with water-mixable oils. Water is used for cleaning your brushes, but the thinner gives better flow control and feel when painting.

Would I Recommend Schmincke ‘Medium-W’ ?

Yes, in the right circumstances.
For certain situations, Medium-W can be super useful.

If you have an oil colour you love but can’t find in a water-mixable range, Medium-W can be a clever way to integrate that colour into your palette.

Also, if you’ve already got a studio full of expensive traditional oil paints, it might be worth experimenting with.

If you’re painting away from the studio and want a water-based cleanup, it can be great.

For fluid sketching and cleanup with water, Medium-W fluid provides flow without excessive solvent use. However, if your goal is to work with water as cleanup, I would recommend building your palette around water-mixable oil paints.

Cost Comparison: Medium W to Water-mixable Oils.

If you mix in the Medium W, this means that for every small squeeze of paint, you need to add half f as much fluid or gel medium.

When you scale that up across six or eight colours on your palette, you can end up using quite a lot of medium, which quickly adds to the cost.

• 40ml of the Medium W gel works out at around £9.49
• 40ml of Cobra Yellow Ochre water-mixable oil paint (an earth colour and one of the more affordable pigments) is around £6.70
• 40ml of Cobra Cadmium Yellow Deep is around £13.50.

If you’d like to explore these differences further, I have several free YouTube videos that compare water-mixable oils, traditional oils, mediums, and solvent-free approaches in greater depth.

Water-mixable Oils vs Traditional Oils
Differences between Acrylic and Oil Paint

Further training

And if you’d like a more structured introduction, I also have :

Beginner’s Water-Mixable Oil Painting Course

Beginner’s Traditional Oil Painting Course

Both are designed to guide you step-by-step through the materials, techniques, and painting process from the ground up.

I’m back in the studio, knee deep in a series of oil paintings.

And I’m really enjoying working with the fantastic malleability of oil paint. You can push it around, layer it thickly, and enjoy a long working time and soft, smoky blends.

But.

Even as a seasoned oil painter, when I’m sorting out my brushes, choosing paints and deciding on mediums, the sharp reality hits. Lack of preparation, a few poor habits, and rose-tinted expectations could easily counteract your efforts and enthusiasm.

Here are 7 Oil Painting Truths, so if you encounter any of them, you can smile and dust yourself down instead of letting them derail you.

1. You will get messy, drop paint, and get oil paint in areas you never realised you could.

I’ve found that no matter how careful you are, you will undoubtedly get oil paint on your hands, your brush handle and then get it on your top!

Wearing rubber gloves can improve your clean-up process, and I’d advise wearing an apron or an old shirt. Knowing that you will get it somewhere and being prepared for that.

Also, make sure not to eat or drink in that area, just because the oil paint will turn up where you least expect it. So the more dedicated space you have, the better.

2. You will get overwhelmed by the range of oil colours and different brushes for different techniques.

A small selection of my brushes! why do I still order more?

Every time I open an art magazine, there seems to be another new paint from a manufacturer.

 “Is this the colour I’ve been missing?”

But honestly, the simpler you keep your colour mixing, the better. Just start with a few key colours and maybe a couple of dark earth tones. Those darker colours are great for underpainting or dropping the chromatic intensity. If you choose them well, you can do a huge number of paintings with just two or three colours.

I recently had a bit of a shock when it comes to brushes. I looked through mine and realised I had hundreds. But when I actually paid attention, I noticed I’d been buying the same two or three types over and over again. It turns out those are the ones I keep reaching for.

With oil paint, the biggest difference compared to acrylics is how many brushes you need. With acrylics, you can often get away with using one brush, rinsing it in water, and moving on. But with oils, especially if you want to avoid using lots of solvents, it’s much easier to just have extra brushes ready to go.

You should set aside a few for your darks, a few for your mids, and a few for your lights.

That way, you’re not constantly cleaning, and you reduce the risk of muddy colours from brush contamination. It’s one of the easiest ways to keep your painting clean and your process flowing.

3. You will try to put out too little paint to save money – this is a false economy

With oils, you can squeeze out a blob of paint, and it will last for days, sometimes even weeks. So don’t be afraid to put out more than you think you’ll need and mix more generously. It won’t go to waste like acrylics, where once it dries, it’s gone.

When you’re just starting out, using a student grade white can be a really smart move. Something like Winsor & Newton Winton Titanium White is great value. ( There is an offer on at Cass Arts for £14.50 for two 200 ml tubes)

In this case, unlike acrylics, artist-quality white isn’t as important.

That’s because with oils, to get a clean colour application on top of your existing wet colours,  you usually need to paint thicker and then leave the brushstroke alone.

With acrylics, the opposite is true. You can use thinner layers and still get solid coverage, as long as the paint is high quality and opaque. So with acrylics, I’d always recommend getting the best artist-grade white you can (I like Golden Brand Titanium white). But with oils, a good student white will do the job and actually encourages you to be more generous with your paint, which really helps when you’re learning.

4. You will compare yourself to an artist in a museum. Even one of the best over the last 400 years, against their best work, trained since 11 and drawn every day

Give yourself a break.

I was reading something today about the idea of making a hundred bad paintings. I think it originally came from a film director who said you should make a hundred bad movies. The idea is that if you approach painting with that mindset, you won’t get so precious, and it takes the pressure off.

When you’re starting out, it’s easy to think you’re going to make one incredible painting and that will be it. But usually, that’s not how it works. It might be pretty good, but the real progress comes when you stop comparing your work to other people’s and start comparing it to your own.

Take inspiration from others, of course, but ideally, you want to be able to look back at a painting you did three months ago and think, “I can’t believe I thought that was good at the time.” That’s how you know you’re improving.

You’re becoming your own reference point.

It’s also worth remembering that when you go to a gallery or an exhibition, the work you see is surrounded by so much extra context.

There’s the grandeur of the museum space, the history of the artist, and even the fact that you may have seen the image before, all of which add to its impact. In his 1935 Essay, “The Work of Art in the Age of Mechanical Reproduction,” Walter Benjamin introduced the concept of “aura,” the unique presence and authenticity of an original artwork that stems from its particular history, location, and singular existence.

Benjamin argued that an artwork’s aura is tied to its “here and now”. Imagine your painting being shown on television or displayed in a gallery. It would feel different, too, simply because of the way it’s presented.

5. You will learn more at the easel in 30 minutes than you will from 30 hrs of YouTube videos

It’s so easy, especially with all the content available these days, to fall into the trap of thinking that if you just watch one more video or learn one more thing, then you’ll finally be ready to start painting. But often, that just becomes another form of procrastination.

The truth is, if you pick the simplest subject, one brush, and one tube of oil paint, you will learn so much more by actually painting for an hour than by watching videos for days. Everything that goes wrong and everything that goes right in that session will teach you far more than you expect.

Oils are great for this because the paint stays wet the whole time. You can keep adjusting, softening edges, layering colours, and really exploring how it moves. You’ll learn what kind of brush feels right, how much medium you enjoy using, what colours you naturally reach for, and even what frustrates you.

All of that only comes from doing. The act of painting is the best teacher.

You’ll be surprised at how much you can accomplish in just one hour, even if it doesn’t feel perfect. That hands-on time builds your skills and confidence far more than waiting to feel “ready.”

6. You will feel exhilarated, then deeply depressed, all within the same painting

Painting can really feel like a rollercoaster. When you first start blocking in or sketching out the composition, there’s a rush of excitement. You feel like this could be the one. This painting might turn out amazingly well! And that initial energy is such a great boost.

But as the painting starts to develop, doubts often creep in.

You might start to wonder if you chose the right subject, if your colours are working, or why the paint isn’t handling the way you expected. You start questioning yourself. That’s when the energy can drop, and it’s easy to hit a low point where you think, “This is rubbish, why am I even doing this?”

Then, often out of nowhere, you’ll paint one little section that surprises you. It turns out better than you thought it would. That small win can give you just enough encouragement to keep going.

That’s why taking regular breaks is so helpful.

Step back from the easel.

Squint down at the painting.

Look at it with fresh eyes.

That reset in perspective can really shift how you feel and help you make decisions more clearly. And often, it’s in those final moments that the magic happens. The last highlight, a sharper edge, or a touch of contrast, those small finishing touches can transform the whole piece.

So, the key is to stay with it, ride the ups and downs, and trust that each stage is part of the process. Keep going.

7. You will judge, question, challenge and rebel against the process

When you’re following a tutorial or trying out a new technique, especially if someone has already laid out a process that works, it’s really tempting to think you know better. I found that when I was first starting to paint, even if I was following someone to get specific results, I would still start questioning the steps. I’d think, “This can’t work,” or “Why am I doing it this way?”

For example, if you’re painting on a coloured ground for the first time, it might feel pointless. You might wonder why you’re not just starting on white. Or if you’re asked to work from the negative space first to reveal the positive forms, that can feel really counterintuitive. (this tutorial of drawing the negative of a bike is a good example)

But these techniques often make a lot more sense once you’ve seen them through.

It’s a bit like following a recipe. I think people tend to fall into two camps.

One group follows the instructions closely, measuring everything precisely. The other group wings it, adding a bit of this or that and hoping it all comes together. Both can end up with a cake, but the results can vary.

When you’re first learning, it really helps to be in that first group. Just follow the steps. Try the full process as it’s laid out, even if it doesn’t make perfect sense yet. That way, you get to experience how these techniques work in practice, and you’ll start to build a foundation you can later adapt to suit your own style.

For students wanting to make the leap from acrylics to Oils, many of the techniques throughout the teaching on the site stem from my training in classical oil painting. So if you’ve been working through the tutorials, you’ve been developing oil painting skills by stealth!

Hope this helps, have a great creative weekend.

Cheers,

Will

Morning class,

This week, I’ve been painting a small postcard study of a street scene in Mousehole on the Cornish Coast. It was a really grey day, full of a mizzle sky and lots of rain reflected on the road.

I liked how this view had dashes of yellow from the double yellow lines that had faded out. These matched the same colours as the hedge on the right-hand side.

There is some warmer orange yellow in the roof, and in the very far distance, just above the chimney, you can see the little cottages that go around the harbour. (You can see a sketch of the harbour towards the end of this article)

Downloadable Reference Image for the Painting:

If you click here is a 20 x 20cm larger scale version

Materials you will need:

• 4 x 4-inch or 6 x 6-inch square canvas board or canvas (It would also work on a larger scale)
• Palette Knife for mixing Oils Paints
• Pencil or Acrylic marker to draw out
• Hog hair round brush for blocking-in
• Small Round brush

Oil Paint Colours

This was the palette I used on for the painting, I wanted some low chroma colours. (You can learn about Chroma here)

• Titanium White (Winsor & Newton)
• Cadmium Yellow Pale (Winsor & Newton)
• Indian Yellow Red Shade (Michael Harding)
• English Red (Old Holland)
• Green Umber (Old Holland)
• Cobalt Blue Hue (Daler Rowney)
• Raw Umber (Michael Harding)
• Ivory Black (Zecchi)

Peter Paul Rubens, Detail from The Assumption of the Virgin, Oil on Panel, 1626

Ruben’s House & the Art of Antwerp

The rhythmic sound of African drums echoed through the vast interior of the Cathedral.

It was an unexpected acoustic experience, and the historical tour we’d seen advertised was looking increasingly unlikely.

There was just Vanessa and me waiting patiently at the back of the Cathedral when the tour guide arrived; she was getting extremely agitated. She hadn’t known the performance was on, the volume was too loud, a new musical set had just started, and her tension was building.

She was miffed.

But then our saviour came, a gentleman from Romania. Our tour of two had become three. We were off to the races.

I was in Antwerp (just last month) exploring Ruben’s home and studio, but nothing had prepared me for the pure brilliance of his works that lay only a few steps from our hotel lobby, hidden behind the doors of the Cathedral of Our Lady.