Achieving smooth, even colour in EcoPour, Jesmonite, and other eco-resin composites is one of the most common challenges makers face. You measure carefully, mix with care, add your pigment… and then demould the piece only to find mottled patches, streaky colour, or uneven layers.

This guide explains exactly why colour stratification happens, how to prevent patchiness in your Eco Pour pours, and the step-by-step method to achieve professional, consistent colour results every time.

Whether you’re creating homeware, coasters, trays, jewellery, or décor, this article will help you troubleshoot and confidently control your colour outcomes.

What Causes Mottled or Patchy Colour in EcoPour & Jesmonite?

Mottling in composite based eco-resins is not random, it’s caused by predictable interactions between your pigment, your EcoPour/Jesmonite slurry, and the timing of your mix. 

1. Inadequate Pigment Dispersion

Water-based pigments are highly concentrated pastes. When added directly to a thick 3:1 EcoPour or Jesmonite mix, they cannot spread easily through the dense slurry.

This leads to:

• Pigment clumps
• Light and dark patches
• Visible streaks
• Colour settling towards the bottom

The result? Uneven, mottled colour in the finished piece.

2. Adding Pigment Too Late

EcoPour and such products begin their initial set very quickly, sometimes in just 3–5 minutes.

If the pigment is added after the mix has started thickening, it becomes impossible for the colour to move and disperse evenly. This creates clear stratified lines and patchy areas which present as dots or speckles. 

3. Uneven Water Distribution

A 3:1 Eco Pour-to-water ratio results in a naturally low-water mix. When thick pigment paste is added undiluted, it introduces localised pockets of excess moisture.

This creates:

• Layers of lighter and darker colour
• Visible “bands” in the set piece
• Irregular curing, causing patchiness

This water imbalance is a major cause of unwanted mottled effects.

How to Prevent Mottled Finishes in EcoPour & Jesmonite,

Step-by-Step

 

 

These are the core methods professional makers use to achieve smooth, consistent colour in gypsum-based eco-resins.

Step 1: Pre-Disperse Your Pigment (The Essential Fix)

Never add thick pigment paste straight into EconPour or Jesmonite.

Instead:

• Mix 1 part pigment with 2–3 parts clean water
• Stir until fully smooth and uniform

This creates a flowing pigment solution that disperses effortlessly throughout your mix.

Step 2: Add Pigment at the Right Time

Introduce your pre-mixed pigment solution immediately after combining your powder and water, before the mix begins to thicken.

The mixture should be:

• Smooth
• Pourable
• Free of dry pockets
• Still in its early fluid stage

This ensures the pigment has full mobility and blends evenly before curing begins.

Step 3: Mix With Purpose

Proper stirring prevents colour separation.

Mix:

• Quickly
• In a consistent direction
• For 10–20 seconds
• Using a silicone spatula or sturdy mixing stick

Scrape the sides and bottom to avoid unmixed zones. This is especially vital for large batches, where dead spots can easily form.

Step 4: Test Small Pigment Amounts First

EcoPour and Jesmonite take pigment differently depending on brand, water content, and environment.

Start small:

• Add 1–2 drops of your pre-dispersed pigment mixture
• Observe the colour outcome
• Increase gradually to deepen the shade

This step reduces waste and gives you predictable colour results.

Why This Method Works (The Simple Science)

When pigment is pre-diluted and introduced early:

• Particles remain suspended rather than settling
• Density stays consistent throughout the mix
• Water distribution stays even, preventing patchy curing
• Initial setting happens uniformly, locking the colour in place

This produces the smooth, even, professional finish that artists and homeware makers aim for.

Can Mottling Be Intentional? Absolutely.

While this guide focuses on avoiding mottled effects, colour stratification can also be used creatively to produce:

• Cloudy gradients
• Stone-like textures
• Soft organic marbling
• Earthy terrazzo-style depth

Once you master consistency, you can control mottling to create intentional artistic effects.

Final Thoughts:

Mastering Colour in EcoPour & Jesmonite

Uneven colour in EcoPour or Jesmonite can be frustrating, but the solution is straightforward. When you understand pigment behaviour and mix timing, you gain full control over your colour outcomes.

To recap, you can prevent mottled, streaky, or patchy finishes by:

• Pre-dispersing pigment properly
• Adding colour before the setting phase
• Stirring thoroughly and efficiently
• Testing small pigment batches first

And if you want to be a real professional, you can sieve your powder too prior to mixing. 

With these steps, you can achieve rich, uniform, beautifully consistent colour in every project, whether you’re crafting coasters, décor, art pieces, or jewellery.