• Justin Cooke

Adding stuff to paint.

How to make paint thicker.

However you buy your paint; by the tube/ in a bottle or tub - It seems every manufacturer has an idea of how paint should be. And there are plenty of manufacturers to choose from. Some manufacturers choose to make their paint thick like toothpaste, others make it’s so liquid you can pour it.

Even with the variety available, you may easily find yourself making do with something you like but you know; it’s not perfect. It is good to be a little fussy from time to time and maybe now you want something a bit different than what is mass produced.

Just to make things even more complicated, you may have found the colour you really like made by one manufacturer, and although it is a good paint, occasionally it is unsuitable. It is not made to the consistency you need. You wish you could find it it in a more thick and dense form than it is when you buy it; because you would like to use a palette knife to paint with perhaps. If only they had made it thicker.

Making paint more liquid is fairly straight forward. You could add water to acrylic paint and turpentine and oil to oil paint. In fact, if you want to go down this route, there is a whole range of manufactured products you can mix with your paint that will do the job. Some of these not only make your paint more fluid but can also make it glossy or matt, dry faster…or even dry slower.

· But what if you want to make your paint thicker in consistency?

· Is there also a way of making the colours stronger?

· Is there anything that could be added to the paint to give it more body; make it more like a paste?

· Could you make paint thick enough to use a palette knife without those blade marks slowly softening and melting away before your eyes?

The answer is, thankfully, yes!

Here’s how it’s done.

There are things artists have always added to paint to change its texture and add what we call ‘body’. Some of these things behave differently with oil paints than they do with water based paints such as acrylics, but I will come to that later.

Let’s look at some of the things we can add.

Clockwise from top left.

Pure pigment




Now…each of these come’s with a warning.

Pure Pigment.

You can enrich the colour of your paint and add a little body to it by adding some more pigment to it. Pigments are sold in powdered form in much the same way as they have for centuries. L. Cornelissen and son, London, have been selling them since 1855. You will need to carefully match the pigment to your paint. Look at your tube of paint, it will tell you the pigments used to make it. This makes it very easy to add a bit more. The binders already in your paint should hold them quite well.

· In acrylic paints, the binder will allow for all sorts of things to be added. Think of it as a glue.

· In oil paints it is the actual oil used in the paint (linseed or rapeseed oil) that acts is the binder

· In watercolours, the binder is gum arabic, which is water soluble. Note, for watercolours you can enrich the colour this way but I would not attempt to thicken it or change its texture…think of it as a way of adding a little more pigment to intensify the colour. But really, it is not generally necessary to tamper with watercolour paint in this way as it is inevitably used with water. To use it you need to make it more fluid, not thicker. For better results colour wise, It is best to use a good range of good quality watercolour paints.

So for now, let’s just think of acrylic and oil.

Adding pure pigment: It enriches the colour.

Pure pigment can be added to both acrylic and oil paint. It enriches the colour. Effectively you would be changing the proportions of the paint recipe and just loading in more pigment. Pigments can be very expensive and you can see the obvious point… you could easily find yourself making an expensive version of the better quality paints that are readily available anyway. So I would check what is available first.

Take care: some pigments can be toxic, so I wear gloves, use a dust mask and to protect the environment… no washing the excess away down the sink!

Talc (talcum powder.

Talc is a mineral powder and is not soluble in water, it is fairly inert and you will find that it doesn’t change the colour of your paint much. Because it acts as a filler it adds body to the paint, which can be useful if you want to use a palette knife to paint with or use an impasto technique.

(Impasto. Using thicker paint in a way that shows brush marks and gives the actual painting surface a texture.)

Adding talc will also help make transparent colours (such as most yellows) become more opaque and therefore cover better over dark backrounds by virtue of being thicker (having more body).

Take care, do not breathe it in.


Sand is very much like talc but it will add a gritty texture to your paint.


Now it gets tricky.

You can use powdered chalk as a filler in paint, but please note, when chalk is added to oil paint it goes transparent. It does not make the paint whiter as you may expect. Turner added chalk to his paint as an extender. I hope to explain a little about what he was up to on the Masterclass pages soon.

Remember; chalk in oil paint goes transparent and changes the feel of the paint… but that’s for later.

Have a go, and then experiment.

If you want to have a go at changing your paint in this way. As a first step, I would suggest adding talc and using a knife or a stiff brush to paint with. Your art supplies shop will certainly have a variety of other products which can be added to paint. You will find, as well as thickening products, pots of stuff that will make your paint have all sorts of textures, there are even tiny glass beads that can be added to paint. There is an additive that will make your paint iridescent and another that is a sand/gel medium. Experiment, paint doesn’t have to be limited to how it comes out of the tube!

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