Celebrating World Ocean Day
Dive Into Colour: Painting a Seahorse with Inks! Watercolour inks, Acrylic Inks and Drawing Inks.
If you have ever wanted to dip your toes into vibrant ink illustration, now is the perfect time to take the plunge! Inks are a joy to work with—fluid, bold, and beautifully blendable. Whether you’re a seasoned illustrator or a beginner looking to explore colour in a new way, inks are perfect for adding that extra splash of life to your work.
In this blog, we will show you just how easy it is to create a whimsical seahorse illustration using a variety of Inks. Inspired by the flowing forms and iridescent colours of underwater life, this project is perfect for experimenting with transparency, layering, and fine detail.
Why Use Inks?
Inks are renowned for their vibrancy, quick drying times, and versatility. They can be used straight from the bottle or diluted with water for beautiful washes, much like traditional watercolours. Best of all, they work on a variety of surfaces and are intermixable—meaning the colour possibilities are endless.
What makes inks a go-to for illustrators and designers is their rich pigmentation and excellent flow, which allows for both detailed linework and loose, expressive washes.
Firstly let's distinguish what the differences are between these inks so you can become accustomed to their individual characteristics.
Acrylic inks, Watercolour inks, and Drawing inks are all fluid, pigmented mediums used for a variety of art techniques, but they differ in composition, finish, and permanence.
Acrylic inks are made with acrylic polymer binders, making them waterproof and lightfast once dry, with vibrant, permanent colours suitable for layering and mixed media.
Watercolour inks are typically dye-based or finely pigmented, water-soluble even after drying, and valued for their transparency and fluid blending, behaving like liquid watercolours. They can be lifted with water to create lighter tints or used for glazing techniques when darkening a colour or changing a shade. They are not waterproof when dry.
Drawing inks, often used in calligraphy or pen work, can be dye- or pigment-based; some are waterproof while others are not, depending on the formulation (e.g., India ink vs. fountain pen ink). Always check individual Brand guidelines.
While all three share high fluidity and can be applied with brushes or pens, their key differences lie in solubility, lightfastness, and suitability for layering or wash effects, making each best suited for specific artistic needs.
We used all three for our Seahorse illustration to see how compatible they were with each other.
Materials You’ll Need:
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You can use any inks for your illustration as this is just a bit of colourful fun! However we used Winsor & Newton Drawing Inks, Liquitex Acrylic inks and Colorex watercolour inks (Dr. Ph. Martin's Radiant Concentrated Watercolour inks are also great to use).
- Watercolour paper (preferably hot press for smoother details).
- A fine-tip brush for detail (size 0 or 1).
- A round and flat brush for washes (size 4–6).
- Pencil for sketching.
- Water jar, palette, and a paper towel.
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White gel pen, we used Pentel Hybrid Gel Grip DX - White you could use any coloured gel pen for the details, even metallic gel pens such as Pentel Hybrid Dual Metallic Gel Rollerball - Mixed Colours (Pack of 8) would look great!
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PDF link to Seahorse for an easy transfer.
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Before embarking on your final illustrations, it is good practice to test out all your colours first. Some colours look different in their containers than on the paper and almost all colours dry a slightly different shade too. We tested the Windsor & Newton Drawing inks. Dye-based: Bright, transparent colours, but not lightfast. Shellac binder: Adds gloss and water-resistance when dry. If the inks are diluted with too much water they are not waterproof. Preferably diluted with Distilled water. |
| We tested Liquitex, Magic color, Colorex and Daler Rowney FW inks.
Always annotate your swatch lists so you can easily reach for that perfect colour. Acrylic inks can be diluted with a small amount of water to extend or dilute them. Creating swatches of colour will allow you to see how colours are either opaque, semi opaque or transparent. |
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Ink options!
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Brush options!
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Step-by-Step: Painting a Seahorse
1. Sketch Your Seahorse
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Start with a light pencil sketch of a seahorse. Think gentle curves and swirls—nature’s underwater filigree. Don’t worry about perfection here; the charm is in the whimsy. If you need a little help you could download our template and transfer it to your watercolour paper. The easiest way to transfer this is to tape the pdf seahorse outline to your window and place the watercolour paper on top. The light will help you see the outline to trace onto your paper. |
2. Masking off areas that you want to stay very light.
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Decide early on where you want the lightest highlights to be and use liquid masking fluid to protect those areas. To ensure you don’t ruin your brush with the masking fluid you can dip your brush in liquid soap first. This will protect the bristles and aid in cleaning your brush afterwards. A good tip would be; don’t use your favourite brushes. |
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3. Lay Down Your First Wash with the watercolour inks, so you can lift colours for highlights if you need to, these inks do not dry waterproof.
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Mix a light dilution of Ultramarine and gently wash over the area around the seahorse, keeping the pigment lighter in some areas to create depth. The ink glides effortlessly with water—no dragging or blotching—making it perfect for gradients and glazes. We used the watercolour inks first so we could lay them on in glazes and pull the colour out in the places we wanted to keep highlights. This was the first of many, many layers of ink. When working with inks it is definitely best to work from light to dark. |
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4. Add Detail and Colour Variation
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Layer in some Lemon Yellow or Canary Yellow, Crimson and Brilliant Green into the coral and seaweed either side of the seahorse. When applying inks on a damp base, the colours will bloom and blend organically—it’s like watercolour with a bolder, brighter twist! We used a Sepia coloured ink for the Sea Bed and a violet for the rocks. You can work on slightly damp paper so your inks can blend and bloom for texture or work on a dry paper surface to keep control of your shapes and colours. Both techniques work really well here. |
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5. Working with Glazes to deepen tones and create layers of colour.
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Once all the base colours were painted and left to dry, strips of masking tape were used to create some beams of light over the sea horse.
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A glaze of diluted inks were painted over the background. We used Ultramarine ink, Turquoise ink and a Violet ink to create many layers of colours, each layer influencing the layer beneath. We left each layer to dry before we painted another one on top. This layering, glazing technique adds a beautiful depth to your illustration. |
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Once the first layer was dry the masking tape was removed and clean water was used to blend a little colour over the rays of light coming through the deep ocean. A little lemon yellow was used to accentuate the light rays travelling through the water. Darker tones were layered to increase contrast after the initial washes dried, adding depth to the work. The liquid masking was also removed once the background ocean was painted and before the seahorse was painted.
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6. Fine details added to create texture
Using a palette of greens such as Hookers Green and Brilliant Green, accented with Fluorescent Yellow ink, various dots and highlights were added to the seaweed and coral to make them appear alive. The light, imagined as filtering downwards through water, dictates a lighter shade on the upper portions and a deeper hue at the base of the coral and seaweed. Don't forget to add a little shadow under the rocks with a blue or purple colour.
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7. Colouring the Seahorse
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Finally we painted our seahorse with inks. We used Liquitex Fluorescent Yellow to accentuate the outline of the seahorse and some of the details within, adding line details to the seahorse’s ridges, snout, and spirals. The ink’s high pigment load ensures crisp lines even with the finest brushes. Lots of layers of small dots and dashes in several colours created the illuminated effect of the seahorse. We used colours such as; Fluorescent Pink, Crimson, Magenta, Yellow medium, and Process Cyan. Lunar White was used to create a pale Blue opaque colour. We add a few splashes or flicks of colour around the seahorse to evoke movement or bubbles to create an underwater dreamscape!
6. Final Touches using a Gel pen, Refine with Linework.
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A white gel pen was used to add lots of detailing on the seahorse, seaweed, and the rocks and coral. You could use a silver, gold or glitter gel pen to add beautiful touches of shimmer and reflection.
Tips for Working with Inks:
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Cover all surfaces you want to protect with a plastic sheet. Mostly all inks will stain surfaces and clothes and skin.
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Work light to dark: Like with watercolour, start with lighter tones and build up to avoid muddying colours.
- Test colours first: These inks are vibrant—test on a scrap piece to get a feel for dilution and drying time.
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Mix with purpose: You can mix inks for custom shades, but always test how they react with water to avoid surprises.
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Wear protective clothing or old clothes and as inks do stain the skin, think about wearing latex gloves..
- Watercolour inks, when used on their own, might require a varnish application. This helps maintain colour vibrancy and prevent fading over time. Sennelier Watercolour Varnish - 75ml
Ready to Dive In?
Creating a playful seahorse illustration with Inks is not only easy—it’s deeply satisfying. The way these inks dance on the page, blend seamlessly, and deliver vibrant results with minimal effort makes them a joy for artists of all levels.
So go ahead—grab a brush, let your imagination swim free, and let coloured Inks bring your art to life.
🎨 Downloadable Seahorse Template
To help you get started with your Ink illustration, we've created a simple seahorse line art template you can print, trace, or transfer onto your preferred watercolour paper.
This template features clean, flowing lines to guide your brushwork while leaving plenty of room for creativity, colour experimentation, and personal flair.
👉 Click here to download the Seahorse Template PDF
Whatever your choice of medium wet or dry, make it an opportunity to be curious and have lots of fun learning about the endless possibilities of using inks and celebrating World Ocean Day!
Tag us on Instagram so we can see all your amazing creations; 🖌️ Shop Inks here 🎨 Share your seahorses with us on Instagram using #ARTdiscountInks #Colouringthenation.
