Using salt in watercolor painting is one of the most fun effects, but it's unpredictability generally relegates it to a bit of a novelty effect.  However, if you understand the factors at play when using salt in watercolors, it can become legitimate technique.  To get the results you want each time there are a few things to know...

How Does Salt Effect Watercolors?

First off, let's briefly go over the effect salt has on watercolors: If you sprinkle salt across wet watercolor paint, it will create a textured or mottled effect that is significantly more noticeable than granulation.

 

 

This effect has been used to create stars in the sky, texture on a sandy beach, or even the speckled pattern on the back of a horse.  It is a wonderful tool to have un your chest, and one that is unique to water media.

Salt + Watercolor: How Does It Work?

In a nutshell: salt absorbs water.  So, when you sprinkle salt onto the surface of a wet watercolor painting it will pull in and absorb the water it touches.  (It is essentially lifting the color as it absorbs it.)  The effect is that little starbursts are created where color has been lifted from the areas where a grain of salt rests.

Salt absorbs water because it is hygroscopic (meaning it has a tendency to absorb moisture).  This attraction is caused by the polarity of the salt and water molecules.  (Polar molecules possess regions that have both positive and negative charge.)  In the case of water and salt, a water molecule (hydrogen dioxide) contains hydrogen which is negative and two oxygens which are positive.  A salt molecule (sodium chloride in the case of table salt) contains sodium which is positive and chlorine which is negative.  As a result, water and salt molecules are strongly attracted to each other (just think of the strong attraction between the positive and negative sides of a magnet).

Another useful thing to know about salt and water is that salt is deliquescent, which means that it can absorb so much water that it turns into a solution, which starts to happen above about 75% humidity for salt.  Before salt reaches that tipping point, it bonds with water to form a hydrate structure.  This is when the salt is still holding the water.

Further, the process of creating a salt water solution is reversible: when the water evaporates a salt residue is left behind.  

Understanding each of these facts will allow you to turn using salt with watercolor into a controllable technique rather than just a fun novelty effect.

What Kind Of Salt Do You Use With Watercolors?

You can use any kind of salt with watercolors - there is no single correct type.  However, different types of salt will give you different effects for different reasons.

Different types of salt absorb different amounts of water depending on their grain size, molecular and crystalline structure, polarisation, and trace mineral content.

Grain size and salt type are the main two variables that you will take into account as a watercolorist.  Understanding the rest removes the mystery of what happens on your paper and why.

Common Types Of Salt 

 A selection of different types of salt in our Travel Salt Pinches.

 

Table Salt

Table Salt has a rather small grain size.  It is a highly refined sodium chloride that usually contains potassium iodide (iodized) as well as an anti-caking agent (which is why many of us need not bother with rice grains in the salt shaker).

Kosher Salt

Kosher salt has a rather larger grain size.  It is called kosher salt after the Jewish preparation process of meat which requires it to contain no blood.  Kosher salts are generally refined sodium chloride without additives (and any other trace minerals), standardized across brands, though different brands have different levels of salinity (saltiness).  

Sea Salt 

Sea Salt is naturally occurring, unrefined, and generally large-grained.  It also contains differing accessory and trace minerals, depending on its source (much like natural pigments).

Himalayan Pink Salt

This salt is a natural unrefined sea salt that receives its striking color from our good friend iron oxide.  

 

Hawaiian Lava Salt

This type of salt has a deep black color that can transfer to your paper for an interesting effect!  It is made by evaporating the local waters and receives its color from activated charcoal (which is considered lightfast).

These salts will all behave similarly in watercolors, though you may notice subtle differences between them that depend on grain side, trace minerals, salinity, color, and crystalline structure.  

The best way to find your favorite is to sample and experiment.  We carry a variety of salts in small tins for use as a travel salt pinch.  Shakers can be messy to travel with and give less control than simply using your fingers to sprinkle.

 

How Do You Use Salt With Watercolors?: Understanding Timing

The two very most influential variables at play when using salt with watercolors are grain size and how wet your paper is (pigment and paper  types are important too, and we will get into those in just a bit!). 

Larger grains of salt absorb more water from your paper (creates larger starbursts), and smaller ones absorb less (smaller starbursts).  The wetter your paper is the more work there is for your salt to do.  Too much water and your salt can simply turn into a solution, and after it dries you will be left with salty residue across your paper.  More commonly, the water will dry before the salt dissolves, but too much water and pigment means the salt will be at absorption capacity before much visible effect is noticeable. 

If your paper is too dry when you sprinkle your salt then there isn't enough water for the salt to absorb to have much noticeable visual effect. 

In general, you're going for the in-between moment when the water on your page is still wet and active - not too dry and not puddle-ridden.  The more you practice, the more comfortable you will feel with recognizing the right moment to scatter your salt - and you will also learn how to push that boundary different ways to achieve different effects.  Salt on a wetter (but not waterlogged) page will give you an almost tie-dye effect, where salt on a drier page will have an overall more subtle effect.  

After you have chosen your moment and sprinkled your salt (using your fingers to sprinkle will give you more control than a shaker), then wait for your paper to dry.  

After you paper is dry, gently brush off the salt grains.  It is important to make sure your paper is completely dry before you do this, otherwise you run the risk of smearing any wet or damp patches of color across the rest of your painting.  The wetter your painting was when you put down the salt, the more difficult it may be to remove - just remember to be delicate with your painting.  Also, while salt can be rough and drying on your fingers, it is best not to use an eraser to help remove salt as it can scratch your paper, smear colors, and make a mess!  If you want to protect your fingers use a stiff (clean!) brush or a glove.

Tip:  Take care not to brush your salt off into your water cup or colorpalette!

 

What Watercolors Are The Best To Use With Salt?

 

This is a palette that we designed to contain some of the pigments that give them most dramatic results when salted.  We named it the Starburst Set, after the shapes and patterns salt makes when added to a light wash.

 

The pigment(s) you select to use for salting can have a big impact on the final results.  Not understanding that different pigments offer different results when salted is one of the biggest sources of frustration for watercolor artists - this is also the main reason using salt with watercolors can feel so unpredictable.

Color characteristics (which you can read all about here) are what determines how each pigment behaves - and these influence the results when they are salted. 

• Staining colors will not retreat to reveal as white of paper as non-staining colors. 
  
  
• Colors that disperse and/or have finer pigment particle sizes will be more mobile on wet paper, therefore giving a more dramatic effect. 
  
  
• Non-staining colors with a wider value range will also give a dramatic effect because of the contrast the revealed white of the paper will provide. 
  
  
• Colors with larger pigment particle sizes will be more sluggish with less of a reaction to the salt.  
  
  
• Flocculating colors will also respond less to salt because their particles are less mobile since they tend to cling together.  However, the result is that salt acts to pull in water (and color) from a smaller range, the effect of which is that of fine snowflakes.  After the salt is brushed away, light or white dots remain from where the salt grains lay.
  
  
• Granulating colors also produce less of an effect when salted.  The textured effect of granulation simply makes the effect of salting less dramatic.  Salting granulating colors subtly accentuates the granulating effect, which can be very useful.

Takeaway: colors with finer pigment particle sizes, with a tendency to disperse, and/or with a wider value range will produce the most dramatic effects when used with salt.  Granulating colors will have their texture augmented with the addition of salt.  Colors with larger pigment particle sizes and/or that flocculate will offer the least dramatic results.

 

Which Watercolor Papers Are The Best To Use When Salting?  Does The Paper Make A Difference?

Yes!  Paper is a lesser factor compared to the salt itself and the pigment you are working with, but it can still have a noticeable effect.

Hot pressed papers will give you the most dramatic effect when salting.  This is because the smooth surface gives the lease resistance to the pigments, allowing them to move more easily towards the salt when it is sprinkled.  Rough papers give watercolors a granulated appearance, making the salt effect less dramatic.  The rough surface also makes the journey a little longer and bumpier for the suspended pigment particles.

Sizing is the other factor to take into account in selecting watercolor papers for use with salt.  Watercolor paper can be internally and/or externally sized.  Sizing decreases the absorbency of watercolor paper.  A surface sized paper prevents the water from being absorbed into the paper fibers as quickly.  As a result, there is more "open" time for a wash to flow - or be absorbed by salt.  So, you will notice a more dramatic result with surface sized papers.  (Most common watercolor papers are surface sized, so don't worry too awfully much about this factor.)

 

 

 

Create A Salt Swatch Chart

Salt swatch chart in progress...

 

The best way to determine how each of the colors in your palette will react to salt is to do some testing.  It is wonderful fun to create a salt swatch chart for quick reference, or just for the experience of testing each of your colors with salt.

Just tape out a grid on a sheet of watercolor paper and fill each square with a different color.  At the right moment, add your salt, let dry, then brush off the salt.  I would suggest using just one type of salt for your chart and trying to keep your timing consistent so that the only changing variable is pigment.  

 

You can always make an additional chart to test different salt types!  For this type of chart I suggest selecting just one color so that the salt type is the only changing variable.  

Takeaways

The three main factors in play when using salt in your watercolor painting are: 

1. Type of salt
   
   
2. How wet or dry your paper is
   
   
3. What pigments you are using
   
   
4. Type of paper
    

To feel comfortable using salt as a technique in your painting you will need to practice and experiment with each of the factors above, which should be a lot of fun.

 

There is so much more to say on this topic, however I will end here for now.  I hope you found this information useful, and feel inspired to give salt a try if you have never played with it before!

 

As Always, Wishing You Happy Painting!