How To Use Ox Gall In Watercolor Painting

How To Use Ox Gall In Watercolor Painting

Before I gross you out, let's start, briefly, with why watercolor and ox gall are even a pair.  When browsing the watercolor section of the art supply shop, you've probably noticed a line of little bottles with relatively vague information on the labels.  Ox gall is usually in one of these bottles, sold as a watercolor additive.

How to use ox gall in watercolor painting what is ox gall greenleaf and blueberry handmade watercolor paintsArtist Grade Ox Gall from a number of different companies: Schmincke, Daler Rowney, and Winsor & Newton

Ox gall is used in watercolor as a wetting agent, dispersant, or surfactant, generally to improve flow and/or aid in wetting your paper. We'll explain what that all even means in a minute.

[For relevant terms, I will italicize them the first time they are used as well as the second to help you notice the follow-up explanation.]

First things first:  What is Ox Gall?  

What is Gall for that matter?  Gall is a dark fluid that exists in the livers of almost all vertebrate animals.  It's in your liver too.  It aids in the digestion of lipids (fats) as they pass through your small intestine.  In a nutshell, what gall is actually made of is a combination of lipids and acids involved in the emulsification of fats.  Essentially, gall helps you break down fats from larger particles into smaller particles (in other words: dispersing them) as these nutrients work their way through your body and get absorbed into your system.  

The name Ox Gall might suggest we're using gall from an ox here.  Not quite, but close.  It's most often from cows, likely a byproduct of the cattle industry.  (So, no, it's definitely not vegan.  There are, however, synthetic versions on the market.)

What you are usually holding when you pick up a bottle of ox gall is some combination of cow gall and alcohol.  


So, why use Ox Gall?

There are a few reasons you may find the addition of ox gall to your watercolor practice useful. 

The most common use for ox gall in watercolor painting is as a dispersant.  A dispersant aids in the separation of particles and generally inhibits clumping and settling.  (Think again here about what gall's function is in the body: the breaking up of fats into smaller particles.)  Ever notice how the paint shoots away from your brush the moment you touch it to wet paper?  A dispersant is a common additive in most mass-produced watercolor paint, and is responsible for this characteristic now commonly associated with watercolor paint as a result. 

how to use ox gall in watercolor painting what is ox gall greenleaf and blueberry handmade watercolor paints
Left: color cloud painted using ox gall  -  Right:  color cloud painted with regular water (no ox gall added)


[Side Note:  Most of these companies are not trying to add more "stuff" to their paints for the heck of it; each pigment is a unique chemical compound, and therefore has a tendency toward certain behaviors.  Most paint manufacturers want to offer a cohesive collection of colors that all behave similarly.  So, colors that tend to flocculate (stick together) will have a dispersant added to combat that tendency.  For the same reason, colors with a more intense tinting strength than that all of the others might have a filler added to help take that intensity down a notch and behave more like the other colors.  At G&B, we take the opposite approach.  Our binder is very minimal, containing no fillers, brighteners, dispersants, etc. so that the unique characteristics of each color are highlighted.  The addition of ox gall is an option that we decided to leave up to the artist.  If you enjoy the texture of brushstrokes in your painting then you can use them straight out of the pan.  However, if you prefer your colors to spread or rely on blending techniques, you can change the behavior of the colors by adding ox gall as you work.]


Another reason you may want to use ox gall in your watercolor painting is if you are using a highly sized (in other words: very stiff) watercolor paper (think: Arches 300 lb - so stiff it breaks instead of creases). Paper like this can initially repel the water you are trying to spread across it.  This is where ox gall as a wetting agent comes in: it helps you wet your paper, say if you are trying to use a wash.  Think of how water beads up on high performance athletic textiles, such as a rain shell.  They have likely been treated with anti-wetting agents that help repel water.  A watercolor paper with a lot of sizing is less likely to ripple, but also has paper fibers that are going to initially be less receptive to water because they are less porous (because they are full of sizing).  In a nutshell (without getting into adhesive forces), using a wetting agent decreases the surface tension of the water so that it can be more easily absorbed into your paper.

how to use ox gall in watercolor painting surface tension greenleaf and blueberry handmade watercolors
Water droplets on the surface of watercolor paper.

How are these two functions available from one little bottle?  Wetting agents, dispersants, and emulsifiers, are all types of surfactants.  (Detergents are also a type of surfactant.  You may see some crafters recommending soap as an alternative to ox gall.  I would personally recommend sticking to artist-grade supplies for your artwork.  Soaps can have a number of different additives.  You are essentially including a whole cocktail of other ingredients into your work, and therefore many unknowns.  Ox gall is much more minimal.)  


How To Use Ox Gall in Watercolor Painting

Let's be clear here.  The addition of ox gall is, initially, quite subtle.  You may not even notice much of a difference the first few times you use it.  However, it is exceedingly simple to use: 

Simply add a few drops to your water cup.  That's it!


how to use ox gall in watercolour painting what is ox gall greenleaf and blueberry handmade watercolors

Top:  Ox Gall added to water  -  Bottom:  No Ox Gall used
Note the subtle difference: the application of the gradient on top is notably smoother, while the gradient on bottom is more blotchy.



Personally, I keep a plastic pipet labeled "Ox Gall" rubber banded to my bottle.  Try to resist becoming impatient or overzealous in your addition of ox gall. 


how to use ox gall in watercolors what is ox gall how does ox gall work greenleaf and blueberry handmade watercolors
It can help to label your pipet so you don't forget what it's for.


Try 3 - 8 drops per cup of water (read: 8 drops is the totally excessive high-end.)

Really, you don't want to overdo it because excessive use of any additive to your paint will mess with the chemistry of what is going on.  Use too much ox gall and your colors will appear mealy and completely lack cohesion.

In essence, you might feel the presence of ox gall more than you will see it.  It has the effect of a subtle gravity release.  It gently loosens the attractive force of the pigment particles to one another, relieving you from fighting against them and trying to tease them apart with your brush as you attempt to spread your colors.



Ox gall is one of those extra tools to have in your chest.  If you know how to use it, you can command a wider variety of techniques and subtleties in your painting.  It's completely optional, so experiment and have a little fun working with it.  It may become your new secret weapon - or it may be something you decide is completely superfluous and never use again.  Either way, once you understand what it is, what is does, and how to use it, you can make an educated decision about what is right for your painting practice.


As always, wishing you Happy Painting!

jess greenleaf artist


Jess Greenleaf


Jess Greenleaf

Thank you for very practical blog.
Another use of ow gall. If your palette is in metal or plastic, the water rolls on it instead of spreading like on porcelain. It is difficult to see the real color of the mix. To give a porcelain feel to your palette, take a couple or strokes of little ow gall (I have it in a solid form) with your wet brush : paint the palette with that mix. Wait a couple of minutes for it to dry before using it as a palette.
Another trick to travel light : I am using the inside cover of the metal box as a palette. To do that, I have sprayed white paint on it. Everything holds in your hand or you clamp it on your watercolour board.
Have fun !

Jess Greenleaf

thanks for this helpful article Jess!

Jess Greenleaf

So much good information ❣️Thank you for the detailed information of Ox Gall.
Hope this not also finds you doing well and enjoying the new bundle of joy you have❣️

Jess Greenleaf

I live in Scotland , UK. Do you have any stockists over here?


Jess Greenleaf

Good to know! Thank you!!

Jess Greenleaf

Thank you for your excellent description and uses for OxGall.

Jess Greenleaf

I’m brand new to water color and to your site. I’d never heard of this—thank you for making the information so clear and “vibrant” :)

Jess Greenleaf

Slowly my mind has drifted back to the days of film developing and photo printing. We used Photoflo as a wetting agent. Wetting Agents: Are chemicals which, when used in minute quantities, reduce the surface tension of water. They are usually added to the final wash of films and plates to improve draining. just not that many folks out there anymore who have used a darkroom. 😳📷

Jess Greenleaf

Very interesting. I had heard of ox gall but never known just how to use it. I love learning new things about watercolor as I’m a new watercolorist and striving to improve my art. Thanks for explaining it in detail and giving info on both uses.

Jess Greenleaf

Thank you! I knew what ox gall was and technically what it was used for, but hadn’t ever seen it demonstrated or explained in detail before, this is super helpful, thank you so much!

Now I’m super curious about synthetic options and how they function and what they’re made of!

(The chemistry and science of art/supplies is endlessly fascinating to me, but I am still new to using watercolour so learning it all helps!)

Again, thank you for the clear and very understandable article on ox gall! I’ll be picking some up my next art supply run and playing around. Will also be doing more research!

Jess Greenleaf

Thank you so much for all
The wonderful information.
I have never heard of it used for watercolor.
I didn’t know what it was for. Thank you for educating me and making me more informed.
Iam excited to try it for sunset washes.

Jess Greenleaf

Very informative, thank you for sharing all the info! I have yet to use ox gall, but am tempted to try it out with some of my more settling paints.

Jess Greenleaf

Great article. Thanks for all the information!

Jess Greenleaf

Thank you for the information. I’m still new to watercolor and I always like learning about the paints and papers. I’m enjoying your blog and appreciate the sharing of ideas.

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