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h o w   t o   p r e p a r e   a   c l a y   s u r f a c e   f o r   w a t e r c o l o r

In this tutorial you'll learn:

 

  • What a homemade watercolor clay ground exists of and how it compares to other grounds;

  • The tools and ingredients you'll need to prepare the panels 

  • Two recipes for preparing the clay ground:
    1. a 'quick' recipe containing acrylic polymer
    2. a slower recipe containing hide-glue

  • How to prepare your panels with recipe no. 1

  • How to prepare your panels with recipe no. 2
     

Tutorial video
v i d e o   t u t o r i a l

Short intro to the video tutorial

Would you like to see from up close how panels are prepared with the clay recipes?In this video tutorial I guide you through the preparation of the panels step-by-step.
I also
 compare different test panels to show how watercolor paint reacts to the different surfaces, and you get access to the clay surface blog page, where I give personal feedback in case you need any help. 

- 4 video's with a total length of 37 minutes;

- painting tests on the different surfaces;
- access to my blog for personal feedback:

 

For € 12,50,-

Take me to the video tutorial!


Note: for this tutorial you'll need to sign up and log in to this website. 
A link to this video tutorial is also available on Ali Cavanaugh's Patreon page. If you are already following her as a patron, you'll find the link below the interview we did for the Aligator Podcast in April 2021


 

w h y   c r e a t e  y o u r  o w n   c l a y  g r o u n d ?

Creating your own clay ground for watercolor has many advantages.
Once you've settled on a formula that works for you,  preparing your own DIY panels is a lot cheaper than buying off-the-shelf boards from the store. Plus, unlike store bought panels that come in standard sizes, you can prepare your panels in any size you want. In the case of prepared clay panels, you will also find that layering on them is very easy, and colors are rendered rich and bright. In this respect, DIY clay panels work a lot like aquabord. Especially the layering and glazing goes on just as smooth, or maybe even smoother than on aquabord.

The great thing about the homemade clay ground is that you can make it as absorbent - or less absorbent - as you want. It is therefore a great surface for rich blooms, and it has the ability to lift color, or scrub areas that need to be reworked. 

Background clayground II.jpg

A few things to consider before you start:

When preparing the clay ground for the first time, I recommend preparing a few small test panels with for each panel small adjustments to the original recipe. The recipe I share is pretty standard, and should work for most people. But, since it contains natural ingredients, the prepared clay mix could end up being different in viscosity and texture. This depends on where in the world the natural ingredients were sourced. This goes especially for the kaolin clay. This type of clay is found and mined in many different places all over the world and therefore, the absorbency of the different brands of kaolin can slightly differ. 

Preparing test panels allows you to find out what ratio between the different ingredients works best for you. In the end this will save you a lot of time, frustration and wasted panels!
 

Another thing is getting familiar with a new painting surface. I believe every watercolor ground has its own unique set of qualities that will help you to establish a particular texture, style or appearance of your painting. In most cases, it takes a while to get used to a new surface, and it will probably take some practice before you get the most out of the qualities a surface has to offer. Having said that, I believe not all grounds are perfectly suited for every painting style, however familiar you feel with that surface.
 

So, when you are trying out a new surface like the homemade clay ground, make sure you are open to experimentation, and allow the ground to grow on you. You might feel comfortable with this ground from the very start - that's how it was for me - but it's possible you'll need a few rounds before your style of painting begins to flourish on it. 
 

 

As with all DIY panels, it takes time to prepare them. Before your panels are ready to go, it will take a few days to prepare the clay recipe, to apply the clay mix onto the panels and to let them dry. If this doesn't sound discouraging to you, and if you follow the recipe with love and patience, the DIY clay ground can be a great, solid and versatile surface to work on. 

Panels.jpg
w h a t   y o u   n e e d

I have developed two recipes for the watercolor clay surface.
Both recipes contain ingredients that are from natural origins and that have been used successfully as painting substrates for years, some of them even for ages. The clay mix is acid-free and after preparation, the painting ground is archival and non-yellowing. 


The first recipe contains only a few ingredients and is relatively quick and easy to prepare. The second recipe takes more time to finish, mainly because of the  hide glue that it contains. If you are a vegetarian or vegan, you may want to stick to the first recipe.

t o o l s 

For both recipes, you'll need the following materials: 

 

  • Panels, preferably made of MDF or mason wood. The panels should be cradled or at least 8mm thick (to prevent the boards from warping), prepared with two layers of gesso and / or acrylic polymer, well dried.
    Applying an extra layer of gesso on the backside of the panel, will help decreasing the chance of warping even more. Protect the borders with masking tape if required.
    If this is your first time preparing a clay panel, I recommend to start with small sized boards, not larger than 20x20cm or 8x8'', my first test panels weren't larger than 11x15cm / 4x6");

  • A clean glass jar from 250 to 500 ml (jam or pickle glasses are great since they have a wide opening);

  • Water (boiled or just from the tap);

  • Flat brush suitable for watercolor, some people prefer a hake brush;

  • Something to stir with (spoon or wooden stirrer);

  • Some people like to use a squeegee or silk screen blade to apply the layers evenly.

r e c i p e   n o . 1

Ingredients:

  • 2 Tbsp Kaolin clay (American measure units);

  • 1 Tbsp Chalk (Calcium Carbonate powder, the finer the better);

  • 2 Tbsp acrylic polymer, I use Golden GAC 100 Polymer;

  • 1 Tbsp finely ground Titanium White Pigment (this is optional, to create a whiter surface);

This recipe is enough for 3 panels of 20x20cm or 8x8'',

Simply multiply the ingredients if you want to prepare more panels.

Note: When working with larger panels (larger than 20x20cm / 8x8"), make sure the clay mix is  amply diluted with water when applying onto the panel. The larger the panel, the thinner the clay mix should be. Also, try finishing the panels within a day or two. Applying a new layer of clay mix after a panel has dried for a few days, might cause the new new layer to not stick well.

Click here to go to the instructions for recipe no. 1

 

r e c i p e   n o . 2

Ingredients:

  • 2 Tbsp Kaolin clay (American measure units);

  • 1 Tbsp Chalk (Calcium Carbonate powder, the finer the better);

  • 1 Tbsp Hide-glue Granulate. Make sure you get good quality, the color of the grains should have a blonde, or sandy color. Hide-glue with a darker or greyish color might have less adhesive strength and usually smells rather strong. Also, the color of your clay ground will turn out more dull, if the glue is too dark.

  • 1 Tbsp acrylic polymer, I use Golden GAC 100 Polymer;

  • 1 Tbsp finely ground Titanium White Pigment (this is optional, to create a whiter surface);

  • An additional clean glass jar (so you'll have 2 in total);

  • 1 small saucepan 

This recipe is enough for 3 panels of 20x20cm or 8x8'',
Simply multiply the ingredients if you want to prepare more panels.

Note: When working with larger panels (larger than 20x20cm / 8x8"), make sure the clay mix is  amply diluted with water when applying onto the panel. The larger the panel, the thinner the clay mix should be. Also, try finishing the panels within a day or two. Applying a new layer of clay mix after a panel has dried for a few days, might cause the new new layer to not stick well. 


Click here to go to the instructions for recipe no. 2

 

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recipe 1
Recipe image.jpg
 r e c i p e   n o . 1   p r e p a r a t i o n

A short snippet from the clay ground video tutorial 


Take me to the video tutorial

Instructions:

To the clean glass jar, add 2 tablespoons of kaolin clay, 1 tablespoon chalk or calcium carbonate, and optional, 1 tablespoon of finely ground titanium white pigment.
Mix these dry ingredients well.


Now add a few tablespoons of water, and stir well until the mixture is smooth and thick, like a light cream. The amount of water you'll need largely depends on the kaolin clay you're using, and how absorbent it is.

Keep stirring for a while, until your mixture is like a smooth and soft emulsion.

 

 

Lastly, add 2 table spoons of acrylic polymer, stir in well. 

Make sure that, with this step, you have your gessoed panels and brush ready, because once the polymer is blended in with the water and clay, the polymer will start to harden, which will slowly make your mixture less fluid. 
 

Work on a clean and flat table, and cover it with a plastic sheet to protect it from staining. 

If you do need to wait until you use your clay mix, then add an extra tablespoon of water to the mix without stirring it, close the jar and save it in the fridge.

recipe I prepping.jpg




Applying the layers

Step 1:
Keep a jar or container filled with clean water next to your clay mixture. 
Using your brush, dampen your panels with a few drops of water before applying the clay mix.

With your brush still moist, scoop a bit of the clay mix from the jar and spread it out evenly over your panel. Depending on the size of your panel, you might need a few scoops of the clay mix to cover the whole surface, but not too many: the first layers should be applied very thinly, like a semi-transparent film.  
 

 

Step 2:
Dip your brush in the water again, and, as if you're applying an ink wash, brush over the surface very lightly, from top to bottom in horizontal continuos strokes, carefully evening out the clay mix layer, adding more water if needed, smoothening the surface. Remove exceed at the bottom edge with your brush or with kitchen paper. Move to the next panel and do the same thing again, until all panels are covered.  


The next layer should be applied after the first layer has dried enough. It doesn't need to be bone-dry, just as long as there are no moist shimmers. Depending on the climate of your room, this will take about 30 minutes up to an hour.  While waiting for the panels to dry, clean your brush and keep the clay mix jar closed.


Layers are to be applied in alternating directions, this means you'll need to rotate the panel 90º with each new layer. Stir the mixture well before adding a new layer. 

 

After drying, repeat steps 1 and 2 for the next layer. You don't need to sand the layers in between, unless you find the texture to be too rough to your liking. In that case, wait a few hours until the layer has dried completely, and sand lightly with a fine sanding paper.
Between the layers, add more water to the clay mix and stir every now and then, making sure the mixture stays fluid. 
 

Sometimes bubbles appear in a newly applied layer. This has to do with either the layer being spread too thickly, or adding too much water to the layer. Sometimes, but not always, they disappear by themselves. To remove any bubbles, I usually touch on them very lightly with the tip of a wet brush. 
 

Continue repeating steps 1 and 2, until you have applied at least 5 layers of the clay mix, or until you find the surface right for you. I would limit the amount of layers to 8, since too many layers may cause cracks to appear.
 

Towards the end, you might notice the clay mixture's consistency gets thicker. This is okay. Just as long as the first few layers are brushed on like a thin film, your surface should be fine. If you apply the first layers too thickly, cracks may appear while the panel is drying. 

After applying the final layer, you might want to use a squeegee or silk screen blade to even out the final coating. Move the blade softly but quickly in one streak over the entire surface, applying a minimum of pressure.
 

 

Your panels should now be ready and perfectly smooth. You don't need to sand them if you don't want to, but if you like an even smoother surface you could give your panels a light sanding. Do this just before you start using them.  
 

When you're finished preparing the panels, allow them to dry for at least 24 hours before working on them. I usually let my panels dry for a couple of days, sometimes even a week. A newly prepared panel might seem perfectly dry the next day, but the curing of the surface actually takes a few days.



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recipe 2
Claymix glue.jpg
 r e c i p e   n o . 2   p r e p a r a t i o n

In this video, I guide you through recipe no. 2 step by step.

Take me to the video tutorial

About hide-glue

Recipe 2 is similar to the first one, with the difference of one ingredient: hide-glue, sometimes called rabbit skin glue. This natural adhesive has been used to prepare artists' panels for ages. The great asset of hide-glue, apart from its adhesive qualities, is that it renders colors very bright and luminous. This is especially true for watercolor paints. The only drawback is that a painting ground prepared with hide-glue takes longer to prepare, and also requires some skill, since you need to work relatively fast. The glue should maintain a temperature around 40 ºC / 104 ºF during the process of preparation, otherwise it will solidify. 
 

Another important thing to remember is that the glue shouldn't be exposed to temperatures higher than 60 ºC / 140 ºF, or it will loose its adhesive strength. To prevent this, it's best to heat the glue slowly in a saucepan filed with water, and keep it in the pan after the heat has been turned off.


One last thing: hide-glue is a natural product and once it has been in touch with liquid, it can spoil if not stored well.  Always use clean jars and tools, and when not in use, the glue is kept in the fridge. Prepared hide-glue can be stored in a cool place for about a week.

 

HIde glue granules.jpg

hide-glue granules

 

Instructions:
 

The night before, add 1 table spoon of hide-glue to one of the jars.
Add about 1/4 a cup (3-4 tbsp) of water to the glue, and stir a little.

Close the jar and keep it in the fridge overnight.
 

The next day, fill a small saucepan with enough warm water to cover the bottom.
Take out the hide-glue from the fridge, and let the jar sit in the saucepan until you'll use it again.  
To the other jar, add 2 tablespoons of kaolin clay, 1 tablespoon chalk or calcium carbonate, and optional, 1 tablespoon of finely ground titanium white pigment.
Mix these dry ingredients well.
 

 

At this stage, make sure you have your gessoed panels and brush ready to use. Work on a clean and flat table, and have it covered with a plastic sheet to protect it from staining. 
 

 

Now we're going to heat up the hide-glue.
Place the saucepan with the water and the hide-glue jar inside, on a low fire.
Once the hide-glue starts melting, begin stirring it slowly with a wooden stirrer, until the mixture is totally fluid. The temperature should be between 40-60 ºC / 104-140 ºF but not any higher (you can't leave your finger 5 seconds in the water without burning yourself). 
 

Take the pan off the fire and leave the jar inside. 
 

 

To the other jar, add a few table spoons of warm water to the dry ingredients, and stir well until the mixture is smooth and thick, like a light cream. The amount of water you need largely depends on the brand of kaolin clay you're using, and how absorbent it is.

Keep stirring for a while, until your mixture is like a soft and smooth emulsion.


Spoon by spoon, add the liquid glue to the clay mixture, while stirring in between. 

Stir in all the glue, and stir well until the mixture is smooth, without any grains. 

Lastly, add 1 tablespoon of acrylic polymer, stir in well.
 

Keep the jar inside the saucepan, and during the whole process, briefly reheat the pan every now and then, to keep the the glue at the right temperature, between 30-40 ºC / 85-104 ºF. On a warm summer day, you can skip this step.


If you need a long break from applying the clay mix, close the jar and save it in the fridge.


 

Recipe II prepping.jpg




Applying the layers

Step 1:
Keep a container filled with clean water next to your clay mixture. 
Using your brush, dampen your panels with a few drops of water before applying the clay mix.

With your brush still moist, scoop a bit of the clay mix from the jar and spread it out evenly over your panel. Depending on the size of your panel, you might need a few scoops of the clay mix to cover the whole surface, but not too many: the first layers should be applied very thinly, like a semi-transparent film.  
 

 

Step 2:
Dip your brush in the water again, and, as if you're applying an ink wash, brush over the surface very lightly, from top to bottom in horizontal continuos strokes, carefully evening out the clay mix layer, adding more water if needed, smoothening the surface. Remove exceed at the bottom edge with your brush or with kitchen paper. Move to the next panel and do the same thing again, until all panels are covered.  


The next layer should be applied after the first layer has dried enough. It doesn't need to be bone-dry, just as long as there are no moist shimmers. Depending on the climate of your room, this will take about 30 minutes up to an hour.  While waiting for the panels to dry, clean your brush and keep the clay mix jar closed. You don't need to store the jar in the fridge, unless you're taking a break longer than 1,5 hours. 


Layers are to be applied in alternating directions, this means you'll need to rotate the panel 90º with each new layer. Stir the mixture well before adding a new layer. 
 

 

After drying, repeat steps 1 and 2 for the next layer. You don't need to sand the layers in between, unless you find the texture to be too rough to your liking. In that case, wait a few hours until the layer has dried completely, and sand lightly with a fine sanding paper.
 

If the clay mixture turns very thick even after reheating, add a bit of warm water and stir every now and then, making sure the mixture stays fluid. 
 

If the clay mixture turns out very thin, then work with a dry brush, and leave out the dampening of the panels. A thin mixture is not a bad thing, it just takes longer to apply the layers, since you'll need more coatings to achieve a solid painting ground. 
 

Sometimes bubbles appear in a newly applied wet layer. This has to do with either the layer being spread too thickly, or adding too much water to the layer. Also, if the clay mix has a temperature higher than 40 ºC / 104 ºF, bubbles are more likely to appear. Sometimes, but not always, they disappear by themselves. To remove any bubbles, I usually touch on them very lightly with the tip of a wet brush. 
 

Continue repeating steps 1 and 2, until you've applied at least 5 layers of the clay mix, or until you find the surface right for you. I would limit the amount of layers to 8, since too many layers may cause cracks to appear.
 

Towards the end, you might notice the clay mixture's consistency gets thicker. This is okay. Just as long as the first few layers are brushed on like a thin film, your surface should be fine. If you apply the first layers too thickly, cracks may appear while the panel is drying. 
 

After applying the final layer, you might want to use a squeegee or silk screen blade to even out the final coating. Move the blade softly but quickly in one streak over the entire surface, applying a minimum of pressure.
 

 

Your panels should now be ready and perfectly smooth. You don't need to sand them if you don't want to, but if you like an even smoother surface you could give your panels a light sanding. Do this just before you start using them.  
 

When you're finished preparing the panels, allow them to dry for at least 24 hours before working on them. I usually let my panels dry for a couple of days, sometimes even a week. A newly prepared panel might seem perfectly dry the next day, but the curing of the surface actually takes a few days.

 

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