Getting eco resin mixing ratios right is the single most important step for a clean cast. The ratio between powder and water determines how the slurry flows into the mould, how quickly it sets, and whether the finished piece is hard and smooth or soft and crumbly.
I'm Anirudh, founder of Artriso. We make CALSO ONE, a single-component water-based eco resin made in Hyderabad. This guide covers the exact ratios, cure stages, and working tips for CALSO ONE specifically, with notes on how Indian conditions change what the numbers mean in practice.
If you are new to eco resin and want the full context before getting into numbers, the complete eco resin guide is the right starting point.
What is the correct eco resin mixing ratio?
The mixing ratio depends on the type of eco resin you are using. There are two formats on the Indian market.
Single-component eco resin (like CALSO ONE) is a powder pre-blended with all the chemistry it needs. You activate it with water alone. The ratio is 3 parts powder to 1 part water, measured by weight.
| Powder | Water | Total mix |
|---|---|---|
| 300 g | 100 g | 400 g (approx. 4 coasters) |
| 450 g | 150 g | 600 g (approx. 6 coasters) |
| 750 g | 250 g | 1 kg (approx. 10 coasters) |
Two-component eco resin (like Jesmonite AC100) combines a mineral-loaded powder with a separate acrylic liquid dispersion. Jesmonite uses a 2.5:1 ratio of powder to liquid, by weight. For any other brand in the two-component format, follow the manufacturer's stated ratio precisely. Do not assume it matches Jesmonite's.
The key practical difference: single-component is one measurement step. Two-component is two. More steps mean more potential for ratio error, especially for beginners and teaching studios. That is why we built CALSO ONE as a single-component product.
Always measure by weight, not by volume
A digital kitchen scale is the only reliable measuring tool for eco resin. Powder can settle, compact, or clump differently in a scoop every time, so cup-volume measurements produce inconsistent results.
A scale accurate to 1 gram is all you need. These are available for under ₹500 at any kitchen or hardware shop in India. CALSO ONE Off White powder, water, and a scale are the entire measuring setup.
CALSO ONE curing stages
Curing is the chemical reaction that converts the mixed slurry into a hard mineral-composite solid. It happens in distinct stages.
Stage 1: Pot life (0 to 12 minutes from water contact). This is your working window. For CALSO ONE at typical Indian indoor temperatures of 24 to 30 degrees Celsius, pot life is 12 to 15 minutes. That is the time from first water contact to the last moment the slurry is workable. Have your moulds, pigments, and tools ready before you start mixing. Do not mix and then pause to set up.
Stage 2: Initial set (20 to 40 minutes). The surface begins to firm. The piece holds its shape. You can gently touch the surface without leaving a mark by around 30 to 35 minutes. Do not move the mould during this stage.
Stage 3: Demould (45 minutes to 3 hours). Thin coasters at 5 mm fill depth are ready to demould in 45 to 60 minutes. Mid-size trays in 60 to 90 minutes. Thick or sculptural pieces in 2 to 3 hours. The test: tap the surface gently. If it sounds solid and does not indent under light finger pressure, it is ready. If it feels warm or slightly springy, it needs more time.
Stage 4: Full cure (24 hours). CALSO ONE reaches full mechanical strength in 24 hours. Do not sand, seal, or stack pieces before this point.
| Stage | Time at 24 to 30°C | Action |
|---|---|---|
| Pot life | 0 to 12 min | Mix, colour, pour |
| Initial set | 20 to 40 min | Leave undisturbed |
| Demould | 45 min to 3 hrs | Remove from mould |
| Full cure | 24 hours | Sand, seal, use |
How Indian conditions change the numbers
The cure times above are calibrated for indoor temperatures between 24 and 30 degrees Celsius. Indian studios often push beyond that range, and the numbers shift accordingly.
Above 32°C: Pot life shortens. At 34 to 36 degrees, you may have 8 to 10 minutes of working time rather than 12 to 15. Mix smaller batches (200 to 300 grams) so you can pour each one before the slurry starts to stiffen. Use room-temperature or slightly cool water, never warm water. Working in the early morning or after sundown is the simplest solution during peak summer.
Monsoon humidity (above 70% RH): High humidity slows surface drying slightly but does not significantly affect the internal cure chemistry. The more relevant risk is the powder absorbing ambient moisture during storage, which causes clumping and compromises the cure. Store CALSO ONE in a sealed container or the original bag folded tight and clipped. If your powder feels clumpy when you open the bag, break up the clumps before weighing.
Air conditioning: A fully air-conditioned studio running at 22 to 23 degrees will give you the full 15-minute pot life and clean, predictable results. If you have temperature control, use it.
Mixing technique
The ratio is the foundation, but technique matters too.
Pour the water onto the powder, not the other way around. Adding powder to water creates lump pockets at the bottom that are hard to break down.
Mix immediately after water contact. Do not wait.
Use long folding strokes with a silicone spatula or a paint mixer attachment on a low-speed drill. Mix continuously for 60 to 90 seconds. The target is thick smooth paint or pancake batter, with no dry streaks or lumps visible. Avoid whipping motions that pull air into the slurry.
Pour within 8 minutes of first water contact to leave a comfortable buffer before the slurry starts to stiffen.
How much eco resin do you need?
CALSO ONE mixed slurry has a density of approximately 1.6 grams per cubic centimetre once poured. A few reliable benchmarks:
A round coaster mould at 90 mm diameter and 8 mm fill depth takes roughly 80 to 100 grams of total mix. A standard rectangular tray at 150 by 100 mm and 15 mm depth takes roughly 350 to 400 grams. A medium planter at 100 mm diameter and 100 mm tall takes roughly 500 to 700 grams depending on wall thickness.
For your specific mould, use the volume formula (length x width x depth for rectangles, pi x r squared x depth for rounds) and multiply by 1.6 to get grams of total mix. Then split by the ratio: total mix divided by 4 gives you the water weight, multiply by 3 for the powder weight.
Common mistakes and how to avoid them
Too much water. A runny slurry produces a weaker, more porous piece. The most common cause is guessing the ratio rather than weighing. The fix is simple: use a scale.
Undermixing. Dry powder pockets inside the cast produce a chalky, weak spot. Mix for the full 60 to 90 seconds and scrape the sides and bottom of the container at least twice during mixing.
Mixing a batch larger than you can pour in time. If you mix 1 kg and then spend 10 minutes slowly filling eight moulds, the last moulds get a partially-set slurry. Mix in staggered batches of 300 to 500 grams for multi-mould pours.
Warm water. Warm or hot water accelerates the reaction and can cut pot life by 30 to 50 percent. Always use room-temperature water.
Related reading
For the full picture on how eco resin compares to epoxy and where CALSO ONE sits in the category, the complete eco resin guide covers it in depth.
For a head-to-head on workflow and price differences between CALSO ONE and Jesmonite, the Artriso vs Jesmonite breakdown is the direct comparison.
Frequently asked questions
Can I adjust the ratio to make the mix thicker or thinner?
Small adjustments are possible. For a thicker paste suitable for laminating onto surfaces or filling gaps, reduce water by 5 to 10 percent. For a slightly thinner pour into very detailed moulds, add up to 10 percent more water. Going beyond these margins in either direction compromises the cure and the final piece strength. For most standard coaster and tray pours, the 3:1 ratio as specified is the right starting point.
Why is my eco resin cracking after curing?
Cracking is almost always caused by one of three things: the cast is too thin (under 4 mm), the piece was placed in direct sunlight or near a heat source while curing, or the water ratio was too high. For thin pieces, cast at a minimum of 6 mm. Cure away from direct sun. Check your ratio with a scale on the next batch.
Can I re-mix eco resin once it starts setting?
No. Once the chemical reaction has started, adding more water and re-mixing will not restart a clean cure. The piece will be structurally compromised. Always mix only what you can pour within 8 to 10 minutes, and have your moulds ready before you start.
How does humidity affect eco resin curing in India?
High ambient humidity above 70 percent does not significantly affect the internal cure chemistry of CALSO ONE. The main risk is moisture absorption in stored powder, which causes clumping and can compromise the cure consistency. Keep powder in a sealed container between pours. During the actual pour, humidity can slightly slow surface drying but does not materially change demould times.
Anirudh Rapole is the founder of Artriso, the Hyderabad studio behind CALSO ONE. Mixing questions? Email contact@artriso.com.
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