Craft Section

Let It Flow: The Art of Thinning Acrylic Paints

by Darin Hlavaz aka Whizard Hlavaz

Often considered an advanced technique, the art of thinning acrylic paint forms the foundation of the mastery-level skills set. As such, most miniature painters come to learn of the technique later in their careers, long after they have mastered the essential skill of brush control. Unfortunately, this approach essentially amounts to putting the cart before the horse, for once a painter comes to learn how to thin paint, he or she must then endeavor to re-master brush control, often reliving frustrations long since forgotten. Had they instead learned how to properly thin paint from the get-go, much time and energy could have been saved for these artists.
That said, there's no better time like the present to learn this skill and to begin applying it to your own work, no matter if you're a fledgling painter just beginning to explore the vast art of miniature painting or a seasoned veteran looking to take your work to the next level. So, what are you waiting for? Let's get you started.

To Thin or Not to Thin?

For those painters concerned chiefly with producing tabletop quality miniatures, applying paint straight from the bottle is generally sufficient for their aim and holds several advantages. It's quicker, saving time and enabling the artist to produce more work in a single sitting. When the paint is adequately shaken or stirred, it's consistent in both color and application, which is particularly advantageous to war-gamers, who often paint large batches of miniatures using the same colors. And finally, for the beginning painter, paint taken straight from the bottle allows for better brush control, as thicker paint generally clings to the brush more readily and doesn't slip and slide all over the place.
Thick paint holds brush strokes.
However, for all of its advantages, using paint straight from the bottle carries a number of distinct disadvantages as well, and these are quite significant to those painters seeking to produce show- or competition-quality models or apply more advanced techniques.
The primary disadvantage of paint straight from the bottle is its viscosity -- it's too thick to be applied skillfully to most miniatures. Being quite viscid, it builds up quickly on the surface of the mini, which obscures details and creates undesirable textures, such as brush strokes and uneven layers. Miniatures end up looking like the woman behind the perfume counter at Macy's, their faces caked with color thick as plaster. What's more, paint straight from the bottle also interferes with the more advanced techniques of blending, layering, and freehand detailing. It adheres to the bristles of a brush rather than flowing smoothly, which, while for the beginner is a boon, is a major disadvantage to the master painter.
Thin paints apply in smooth, even coats.
Thinned paint, on the other hand, applies more smoothly and evenly, resists brush strokes, and, when used skillfully, defines detail, not obscures it. Much like ink, thinned paint flows readily from the brush in a smooth, even coat, affording the artist significantly more control. In fact, it is this likeness to ink that gives thinned paint its advantage. Rather than slathering on a thick paste, you'll now be able to draw upon your mini as you would on a piece of paper. Just consider the number of doors that opens to your creativity.
Unfortunately, thinned paint does carry one significant disadvantage. It's inherently difficult to control without practiced care and finesse, being readily susceptible to gravity and slips of the hand. Add this to an art that already requires a steady hand, and you soon find both seasoned painters with considerable brush control and learners alike abandoning the technique in favor of thicker, stickier yet relatively more well-behaved paint.
For those willing to persevere, however, the benefits are considerable.

Alchemy 101

Difficulty in controlling the paint aside, one of the more infuriating phenomenons for beginners learning to thin their paints is the lack of consensus among veteran artists regarding the best products and composition of thinning solutions. Any number of different painters will offer any number of different preferences, leaving an inquisitive learner bewildered and frustrated. What products should I use? How much of each should I mix together? And so on.
Yet, as with most hotly debated subjects, several sound principles exist, which provide a basis upon which learners can begin their own exploration and experimentation.
At its most basic level, the art of thinning paint requires the artist to add a thinning agent to the acrylic paint to increase its fluidity. This is easily accomplished by adding water, as acrylic paint is a water-based medium. However, several additional additives can be used to better the paint's handling characteristics and increase its drying time -- namely, flow improvers and extenders.

Different painters prefer different products.
Flow improvers, sometimes referred to as "thinners", affect acrylic paint in exactly the manner in which their name implies -- they enhance fluidity and "flow." Unlike water, however, flow improvers don't dilute the pigments within the paint but instead work to maintain color strength and vibrancy by suspending the pigment in solution rather than allowing it to sink, as it will in water. A number of flow improvers also adjust surface tension, which in turn allows the paint to flow more smoothly from the brush. Popular brands of flow improvers include Winsor and Newton Acrylic Flow Improver and Golden Acrylic Flow Release, as well as, believe it or not, Future Floor Finish. Future, mixed one part to four parts water, is commonly referred to among miniature painters as "magic wash" and has become quite popular over recent years. Most serious master painters, however, shy away from using Future and instead rely on products designed specifically for use with acrylics. Ultimately, you'll need to make this decision for yourself.
Extenders, also known as retarders, increase the working time of acrylic paints by extending drying time. By their very nature as a water-based medium, acrylic paints dry quickly as the water evaporates. Extenders help to retain the water, which provides more time for the artist to layer and blend. Extenders are also helpful in reducing "skinning" on palettes. Among the extenders, Liquitex Slow-Dri and Folk Art Extender by Plaid are preferred, although a number of other brands including Golden and Winsor and Newton are also available.
As with brand preference, differences of opinion regarding solution composition abound, though most painters tend to mix some percentage of both flow improver and extender with water. Experience becomes the deciding factor here; with experimentation highly encouraged until the beginning painter has settled on a recipe that suits his or her painting style. Two recipes made popular by award-winning artists, Anne Foerster and Jennifer Haley, are listed below to give aspiring artists a starting point. It's important to note, however, that these recipes are not set in stone. Just the same, many painters come to rely solely on the two proven solutions. Only time and a willingness to experiment will tell for you.

Anne Foerster's Recipe

  • 80% Folk Art Extender
  • 10% Winsor and Newton Flow Improver
  • 10% water

Jen Haley's Recipe

  • 25% Liquitex Slow-Dri
  • 25% Winsor and Newton Flow Improver
  • 50% water
Again, experimentation with these percentages and other products is highly recommended. Different ratios of flow improver to water and extender produce different results in different applications. Jen Haley reports she prefers an alternative mixture of 50% flow improver and 50% water when performing such intricate detailing as blacklining. Other artists prefer to use additional mediums such as gel mediums for other techniques such as glazing and basecoating. Patience and prolonged experimentation will serve you best. So, don't be afraid to play.

Absolute Imprecision

Different brands require different ratios of solution to paint.
As if a lack of consensus regarding products and solutions wasn't enough, most painters learning to thin their paints become doubly discouraged by the lack of precise measurements used by experienced painters when adding thinning solution to paint. The art of thinning paint isn't an exact science. Each brand of paint requires different ratios of thinner to paint for different applications, and as with solution creation, where scientific precision falls short, practice and experience must suffice. Be prepared to spend some time experimenting with different ratios and mixtures until you develop a system that works for you and the brand of paint you use. Don't worry; you'll eventually hit on something that does the trick.
That said, it isn't my intent to leave you in the dark with only whispered promises of perseverance's payoff. Instead, we'll take a look at how I prefer to work with Reaper Pro paints. From there, you should be able to apply the same techniques to whatever brand of paint you use.
For the sake of presentation, we'll be using Jennifer Haley's thinning recipe as listed above -- 25% W&N Flow Improver, 25% Liquitex Slow-Dri, and 50% water. As a general rule of thumb, it's best to pre-mix your solution, keeping it close at hand in a bottle rather than mixing each additive on your palette as you work. You'll save yourself loads of time and energy this way. In fact, a number of artists keep several different favorite mixtures on their painting tables for different applications including layering, wet-blending, and washes. Given sufficient time and practice, you'll most likely develop your own collection as well.

The Flow of Reaper Pro

Straight out of the bottle, Reaper Pro paint is one of the few brands of paint that work well without any thinning. It applies relatively smoothly and isn't so viscid that it builds up thick layers quickly. For this reason, many painters do apply it directly as a basecoat without any thinning. However, like most paints, it does require substantial thinning to be used effectively with a number of advanced techniques. Fortunately, Reaper Pro takes to thinning very well.
Unlike lesser quality paints, such as craft paints, which use inferior pigments, Reaper Pro paint has been formulated with very dense pigmentation that allows the paint to be thinned without losing its color saturation or ability to cover. Lesser brands of paint will become dull when thinned and will require several applications to achieve sufficient coverage. Not so with Reaper Pro. It can be thinned very aggressively and still come out looking beautiful. This is true of several other brands of high-quality model paint as well, but a vast number of these remain virtually unusable straight out of the bottle, being extraordinarily thick. Reaper Pro paint, it would seem, has the best of both worlds. But you're not surprised now, are you?
Regardless of its usability straight out of the bottle, however, you'll still want to learn to thin Reaper Pro paints, even for basecoats. The addition of the extender alone will make working with them much easier as they won't develop a skin as readily, giving you more time to work without shaking or stirring. Besides, thinning your paint makes your bottles go a lot farther, which means you'll have to replace them infrequently, which leaves more money in your pocket for minis. And that's always a good thing.
Now then, thinning your paint will require different ratios for different applications, and this is where the imprecision comes in. While many painters use eyedroppers to add their thinning solution to the paint on its palette, most do not use precise measurements, but instead work through intuition and experience. This frustrates most beginners who prefer to know exactly how many drops are required for basecoating or layering or washing. The key point to remember here is that it's the consistency of the paint that's important, not the precise number or size of the drops added. As mentioned before, each brand of paint requires different ratios for different applications. Here's how I work with Reaper Pros.

Basecoating - 1:1 parts solution to paint
Layering - 4:1 parts solution to paint
Washes - 10:1 parts solution to paint

Basecoats should remain opaque throughout.
In terms of basecoating, the consistency of your paint should be roughly equivalent to the consistency of whole milk. That is to say, the paint should be fluid, yet opaque. You don't want to see any light passing through the edges of the pool of paint on your palette. This consistency ensures that sufficient coverage is achieved and that the paint applies in a smooth, even layer. A number of painters, however, prefer instead to forego this ratio and thin their basecoats as they would were they layering. Again, the choice is up to you.
Thinned paint for layering should appear transparent at the edges.
For layering and highlighting purposes, you'll want to make your paints considerably thinner. I find a ratio of approximately 4:1 solution to paint is best for most Reaper Pro paints, depending on the color. Darker colors generally require one or two more additional drops of solution, while lighter colors often require less. Regardless of color, your end product should result in a consistency that resembles skim milk. The paint should be fluid on the palette and relatively opaque in the center. The edges of the pool, however, should appear more transparent, allowing you to see the palette beneath. If the pool is transparent throughout or the edges opaque, you'll need to adjust by either adding more paint or solution. Just remember it's the consistency that's key here, not the exact number of drops you add on the palette. Using the photos as a rule of thumb should help you to overcome any confusion.
Washes should be entirely transparent.
Finally, for the sake of washes, you'll need to become very aggressive, thinning your Pro paint to a ratio of 10:1. The end consistency should result in a pool of paint that is transparent throughout, enabling you to see the palette beneath with relative ease both at the center and on the edges. Again, it may be necessary to adjust this ratio depending on the color you're using.
With a little tinkering, the above ratios and techniques should prove useful no matter what brand of paint you use, though I'd advise you to proceed with caution. While most high-quality model paints thin very well, you may find that some lesser-quality craft paints quickly lose their color saturation and ability to cover. In these instances, you'll need to apply a number of coats to achieve sufficient coverage and vibrancy on your model. Just beware -- Some very low-end craft paints feature pigments that are not as finely ground as those found in higher-quality paints and, when thinned, become grainy and unattractive. You'll need to use your best judgment on how to thin and apply such paints depending on the results you achieve.

Easy Does It

By this point, we've come to learn how to effectively thin paints for use with a number of different techniques -- basecoating, layering, and washes. And while it is not within the scope of this article to discuss each technique in depth, it would be unfair of me not to make any mention of how thinning your paint will impact these techniques and, more importantly, your brush control.
Right from the start, you'll note the paint behaves differently. Being more fluid, it flows into the bristles of your brush with ease rather than sitting on top. Don't be fooled, however. Just because it appears that very little paint has been drawn into the bristles, doesn't mean that brush isn't fully loaded. You'll be surprised how much paint will flood from the tip of your brush with just the slightest bit of pressure. On a number of occasions, I've watched in dismay as a brush that I thought held only a small amount of paint released its payload like a bomb all across my mini. Don't let this happen to you.

Wick off excess moisture before painting.
Your best bet for avoiding the flood is to quickly dab your freshly loaded brush on a paper towel, allowing the excess paint and moisture to be wicked off. Don't worry. There will still be plenty of paint left behind. In fact, you'll be amazed how much paint a brush can hold when the paint has been properly thinned.
After wicking off the excess moisture, apply the paint to your mini using only the tip of your brush and as light of a touch as you can manage. Given its new fluidity, you'll find the paint flows readily from the bristles, so only the tip need be applied. Otherwise, you'll suffer the flood.
Indeed, it's so easy to flood your miniatures with thinned paint, that I recommend you practice painting on a palette or some other surface until you get the hang of how thinned paint behaves. You don't want to go ruining a good mini, after all, and such practice will save you from agonizing bouts of frustration later. In fact, practicing on a palette is also a good way of learning such techniques as layering and freehand detailing. So, don't be afraid to play around before attempting a mini.

That's a Wrap

Ultimately, the art of thinning paint is a skill developed primarily through experimentation and experience. There doesn't exist a "right way" or a "wrong way". As with most techniques in painting, you'll need to explore a number of different avenues and adopt those solutions and ratios that suit you best. However, so long as you pay attention to the consistency of your paint, you shouldn't have any trouble becoming proficient with this very essential skill.
On the other hand, if you've been painting long, you may find yourself revisiting frustrations of old as you struggle to regain your brush control. As we've discussed, thinned paints behave very differently from paint straight from the bottle. More likely than not, this will require you to relearn many of the techniques you'd thought you'd already mastered. Don't worry, though. The journey is worth it. All manner of new techniques will now be available to you. In fact, in my next article, we'll discuss in depth how thinned paints can be put to good use through layering. Watch for it shortly.
Until then, if you have any questions, feel free to contact me via email or on the Reaper forums.
Oh, and happy painting!

Craft Home