What Happens When You Add Dish Soap to Sumi Ink? A Suminagashi Experiment.

August 21, 2026

Introduction

I made one of these Suminagashi prints the way I've always done it. I made the other with a small amount of dish soap mixed directly into the sumi ink.

Can you tell which is which?

I was watching watercolor artist Liz Chaderton demonstrate Suminagashi when I noticed something I had never tried before. She added a drop of dish soap directly to her sumi ink.

Normally, I keep my sumi ink and soapy water separate. I alternate between the two on the surface of the water to create the expanding rings that are characteristic of Suminagashi.

Adding soap directly to the ink made me curious.

Would it change how the ink moved across the water? Would the finished lines look darker, lighter, cleaner, or more textured?

I decided to test both methods side by side.

I made three prints using sumi ink with dish soap added and three prints using plain sumi ink. I used the same paper and basic process for both and waited until all six prints were completely dry before comparing them.

Watch the full tutorial here:

What is Suminagashi?

Suminagashi is a Japanese paper marbling technique in which ink floats on the surface of water before being transferred to paper.

One of the ways I create Suminagashi is by alternating between sumi ink and soapy water. I touch one brush loaded with ink to the surface of the water, followed by another brush loaded with soapy water.

The soapy water pushes the ink outward, creating expanding concentric circles.

From there, I can leave the rings alone or manipulate them before pulling a print. A skewer or toothpick can create soft swirls, while gently moving the air across the water creates more irregular lines.

One of the things I love most about Suminagashi is that you never know exactly what you're going to get. Even when you use the same materials, every print is different.

For this experiment, I changed just one part of my usual process: I added dish soap directly to the sumi ink to see what would happen.

Materials Needed

For this experiment, I used:

Sumi ink
Dawn dish soap
Fresh water
A shallow tray
Small containers for the ink and soapy water
Two soft brushes
Yasutomo Sketch Paper 6H
Paper towels for drying
A skewer or toothpick for creating swirls
Newspaper for skimming the water surface when needed

I used fresh water for each print during this experiment.

I don't normally replace the water after every Suminagashi print, but because I was comparing two methods, I wanted to start with clean water each time.

Step-By-Step Process

Step 1: Prepare the Sumi Ink

Pour some sumi ink into a small container.

For the first three prints, add approximately one drop of dish soap directly to the ink and mix it thoroughly.

My goal was one drop, although I may have ended up with closer to one and a half or two drops. That may have contributed to some of the texture I saw in the finished prints.

For the second set of prints, use plain sumi ink with no soap added.

Step 2: Prepare the Soapy Water

Prepare a separate container of soapy water.

Even when I added dish soap directly to the sumi ink, I continued using my regular soapy-water brush.

The experiment wasn't about replacing the soapy water. I wanted to see what happened when soap was also present in the ink itself.

Step 3: Load the Brushes

Use one brush for the sumi ink and a second brush for the soapy water.

Saturate both brushes well, but don't let them drip.

I want the brush to hold plenty of liquid without drops falling into the water before I touch the surface.

Step 4: Create the First Rings

Hold the brushes straight up and down, perpendicular to the water.

Barely touch the tip of the ink brush to the surface.

You don't need to push the brush below the water. Just touching the surface is enough for the ink to transfer.

Next, touch the soapy-water brush to the center of the ink.

The soap pushes the ink outward and creates another ring.

Continue alternating between ink and soapy water to build your pattern.

Step 5: Watch How the Ink Behaves

Almost immediately, I noticed something different about the ink containing dish soap. I saw texture inside the black rings.

Instead of the smooth, solid black lines I normally see, some areas looked broken or mottled.

The amount of soap on the brush also affected how far the circles expanded. The longer I allowed the soapy-water brush to touch the surface, the larger some of the circles became.

This is where the experiment became interesting because the soap was clearly changing the appearance of the ink.

Step 6: Manipulate the Pattern

You can print the concentric circles exactly as they are or move them before pulling your print.

I usually prefer soft swirls, so I often use a skewer or toothpick and move it very slowly through the floating ink.

Small movements create a surprising amount of change.

You can also gently fan the surface.

I normally prefer swirls because fanning tends to create more jagged edges, but during this experiment I made one print using that method and liked the result much more than I expected.

Even your breath can move the ink, so work slowly.

Step 7: Place the Paper

I used Yasutomo Sketch Paper 6H for all six prints and placed the smooth side of the paper against the water.

During the first few prints, I noticed a strange line running through the center of the paper.

I eventually realized that I was bowing the paper slightly as I lowered it onto the water.

When I stopped doing that and simply allowed the sheet to drop evenly onto the surface, the center line disappeared.

Make sure the entire sheet makes contact with the surface and that there aren't large air bubbles underneath.

Step 8: Pull the Print

Allow the paper to sit briefly on the surface.

Then carefully lift it from the water and place it on a paper towel to dry.

Don't judge the print too quickly.

Some patterns that didn't look very interesting while they were floating on the water looked completely different once transferred to paper.

Step 9: Repeat with Plain Sumi Ink

After making three prints with dish soap added to the ink, I thoroughly washed my ink brush.

Then I repeated the same basic process using plain sumi ink.

I continued alternating between the plain ink and my separate soapy-water brush.

Again, I made three prints using the same Yasutomo paper.

I tried different ways of moving the pattern, including leaving the circles alone, creating swirls with a toothpick, and gently fanning the water.

Once all six prints were completely dry, I compared the two groups.

Personal Insights and Applications

The biggest difference I noticed was the texture inside the black areas.

Sumi Ink with Dish Soap Added

The prints made with soap mixed directly into the sumi ink had more texture and variation. The blacks weren't as consistently solid. Some areas had a broken, almost grainy appearance. There was more visual noise inside the lines. And I liked it.

It gave me a look that I don't normally get from my usual Suminagashi process.

Plain Sumi Ink

The prints made with plain sumi ink gave me the darker, cleaner blacks I'm used to. The lines were clearer and more solid, without as much texture inside them.

If I wanted clean black-and-white contrast and crisp rings, I would choose my usual method.

But that doesn't mean I think the plain ink is better. I think the two methods simply give me different tools.

If I want clean, dark lines, I can use plain sumi ink.

If I want more texture and variation within the black areas, adding a tiny amount of dish soap gives me another option to experiment with.

Small Changes Matter

This experiment also reminded me how sensitive Suminagashi can be.

The amount of ink on your brush matters.

The amount of soap matters.

How long the brush touches the water matters.

The way you move the water matters.

Even the way you lower your paper can affect the finished print.

That unpredictability is one of the things I enjoy most about the process.

I can make print after print using the same materials and still get something completely different every time.

Project Time

This experiment can easily be completed in an afternoon.

The actual Suminagashi process moves fairly quickly once your materials are set up. Most of the additional time comes from making several prints and allowing them to dry completely before comparing them.

If you're experimenting with two different methods, I recommend making more than one print of each.

One print can behave strangely for any number of reasons. Making three prints with each method gave me a better sense of the differences I was actually seeing.

Conclusion

So, does adding dish soap directly to sumi ink make better Suminagashi?

For me, the answer is no. But it doesn't make worse Suminagashi either.

It's simply different.

Adding soap to the ink gave me more texture and variation inside the black areas.

Plain sumi ink gave me the clean, dark lines I already know and love.

I can see a place for both.

What I like most is that changing one small part of the process gave me another option to work with. It didn't replace the way I've always made Suminagashi. It added something new.

That's usually what happens when I let curiosity lead the experiment.

If you try adding dish soap directly to your sumi ink, compare it with your usual method and see what happens.

Do you prefer the textured blacks or the clean, crisp lines?

I already know this experiment has me curious about what else I can try next.

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