Creating a smooth, beautiful flat wash might look simple, but it often trips up beginners.
If you've been painting skies or sunset scenes and can't seem to get that clean, even wash, you're not alone.
In this article, I'll walk you through how I paint flat washes, the common mistakes to avoid, and the proper techniques to help you build confidence and get stunning results.
Contents
Why Flat Washes Matter in Watercolor Painting
Flat washes are everywhere in watercolor paintings. They're beneficial when creating backgrounds, like soft skies or warm sunsets.
A flat wash simply means applying an even layer of color over a large area without streaks or blotches. That smooth finish gives your artwork a polished, professional look.
But while it may sound easy, getting it right takes a bit of planning and the right tools. Let me show you what can go wrong—and how to avoid it.
Common Mistakes Beginners Make
Let's start with the most significant reasons a flat wash goes wrong. I've been there and want to help you avoid the same mistakes.
Mistake 1: Using the Wrong Brush Size
This one made a huge difference for me. Using a small brush is a big problem if you cover a large area. I remember having to reload paint from my palette again and again.
And while doing that, parts of the paper dried too fast. This left behind harsh, dry brush strokes.
Mistake 2: Not Preparing Enough Paint
Another common mistake is running out of paint halfway through your wash. I used to think I could just mix more when needed.
But that often created problems. The second batch of paint never matched the first—either too diluted or too strong. The wash ended up patchy and uneven.
Once, my second mix was so diluted that I had to paint over it again, trying to fix it quickly.
But by then, the first layer had already started drying. I had to prepare a third, more saturated batch than the first two. That just made the whole wash look inconsistent.
Mixing paint during the wash also eats up time. While you're rushing to mix more, the first strokes start to dry, and it gets harder to blend new paint into the existing layer.
The result? Rough patches and uneven color.
Choosing the Right Brush for Flat Washes
The good news? The right brush makes a huge difference. Let me show you the brushes I like to use and explain why they work so well for large washes.
Types of Brushes That Work Best
You'll want to use a big brush that can hold much water and pigment.
- I often reach for my size 12 round sable brush. It's excellent for covering space while still giving me control.
- Another option is a 1-inch flat synthetic brush. It's useful when I want clean, straight edges in my washes.
- But my favorite brush for large flat washes is the Haig brush. It's made from soft natural hair bristles, and it's super absorbent.
Natural hair brushes soak up more paint and water than synthetic brushes. They stay wet longer, which helps you avoid those dreaded dry lines.
Synthetic brushes are more rigid—they snap back quickly and don't hold as much moisture, making your wash look choppy.
Prepping Your Paints Before You Begin
Once you've got the right brush, the next step is ensuring you have enough paint ready. Make more paint than you think you'll need—seriously.
The bigger your painting area, the more paint you'll need. If your palette runs dry halfway through, you'll have to stop and mix more, which leads to mismatched tones and an uneven wash.
Preparing a full, consistent batch from the start helps maintain the same concentration and color strength from top to bottom.
You'll save time, avoid stress, and get a smoother result.
Two Techniques for Painting Flat Washes
Once your tools and paints are ready, you can start painting. There are two primary methods I use for flat washes: wet on dry and wet on wet. Let's break each one down.
#1. Wet-on-Dry Technique
This is the one I use most often. It means applying paint directly onto dry paper.
I always tilt my paper slightly before starting. This helps the paint flow down naturally, forming a bead of water at the bottom of each stroke.
That bead is key. It keeps the edge of your stroke wet so you can continue painting smoothly without hard lines.
I start at the top and overlap each stroke as I move downward, reloading my brush with paint every time to keep the flow even.
When I reach the bottom of the area, I gently blot the excess paint using a paper towel or a dry brush.
If you leave too much moisture there, it can backflow and create a bloom—or what's sometimes called the cauliflower effect.
Once the wash dries, I ensure not to touch it again. That's important. Any extra strokes can disturb the surface and create unwanted textures.
If I need to darken the area or adjust the value, I wait until everything is completely dry.
Then I paint a second layer, using the same method—top to bottom, with beads at each stroke, and blotting the bottom again.
#2. Wet on Wet Technique
Sometimes, I work in a large area and worry I won't have enough time for the wet-on-dry method. That's when I use the wet-on-wet technique.
There’s one thing to watch for: paper buckling. Wet paper tends to form ripples, which makes it harder to create a flat wash.
To avoid this, I use 300 gsm paper that’s 100% cotton and pre-stretch it before painting.
I start by pre-wetting the paper with clean water. But there's a trick here—you don't want the paper too wet or dry. I try to make it just evenly damp across the entire area.
Once ready, I load my brush and begin applying the paint. Here, I usually switch to a flat synthetic brush instead of the Haig brush.
Since the paper is already wet, using a super-absorbent brush might flood it with too much water and cause puddles.
You'll probably notice the paint looks lighter on the paper. That's because it's mixing with the water that's already there.
So, I mix my paint slightly more concentrated to balance that out.
What I like about this method is that it gives me more time. I can go back in and make small adjustments, tilt the paper to guide the paint and blend everything out.
It's great for scenes with multiple colors, like sunsets, because the transitions look soft and natural.
Comparing Wet on Dry vs. Wet on Wet
Both techniques work, but they give you different results.
- Wet on dry gives me more control. I get cleaner edges and more precise colors.
- Wet on wet is more flexible. I get softer blends and a more atmospheric feel.
I use both, depending on the look I'm going for. I recommend you try them both, too. See which one fits your style better.
Closing Words
Flat washes take a bit of practice, but once you get the hang of it, they become one of the most powerful techniques in your watercolor toolkit.
Use the right brush, prepare enough paint, and be patient during the drying stage. Why not grab your paints today and give both methods a try?