SURFDRY Assisted Drying: The Science and Testing Explained

For 18 months, we investigated a deceptively simple problem:

Why do wetsuits take so long to dry — and what actually makes them dry fast and completely?

We learned two crucial truths:

1. Heat (temperature) is the most important factor in drying. Without warmth, moisture simply won’t evaporate effectively — low temperatures severely limit evaporation regardless of fan power. Source: wtamu.edu

2. Air movement matters — but not in the way most people think. Increasing airflow helps remove humid air near the fabric surface, but beyond a certain point, adding more fan power offers diminishing returns — especially once airflow is sufficient to clear the saturated boundary layer around the wetsuit. Source: ResearchGate

In our controlled side-by-side tests, SURFDRY outperformed natural ambient drying, removing moisture faster and more completely. These conclusions are supported both by our own data and by established drying science.

A wetsuit is not like drying a towel or tee-shirt on a line.

• Thankfully, neoprene, by design, isn’t permeable. In use, cold water is meant to remain on the outside, while we stay warm on the inside. However, when drying, water remains trapped on the inside, even when effective evaporation occurs on the outside.

• Laden with water, folds and seams also create pockets where moisture is held, not just surface wetness.

• Surface tension is powerful. Water sticks to surfaces, which also traps water on the inner facing surfaces of a drying wetsuit.

• Some neoprene is made with open-cell, which while not generally permeable, exacerbates the problem, trapping water within the material itself. This is why wetsuits can feel dry on the outside yet stay eternally soggy.

Most ambient air drying relies on simple evaporation. But evaporation only proceeds effectively when the air adjacent to a given material can absorb new water vapor — meaning access to fresh, warm, unsaturated air is a prerequisite for drying. Source: Reddit

The testing methodology is structured to eliminate bias and isolate drying performance:

1. Two identical wetsuits are weighted and submerged in a deep, water-filled barrel for an hour, then rinsed. 

2. Both are hung in identical ambient conditions, adjacent.

3. After initial drip, one suit is dried with SURFDRY; the other relies on natural evaporation only.

4. Ambient conditions, temperature and humidity as well moisture content through tracking weights is tracked over time. Given known dry weights, presence of moisture is easy to detect. The proprietary data acquisition equipment has weight resolution to 1 gram (a shot glass holds 50 grams of water). 

This side-by-side setup provides clear comparisons and consistent results.

This is a photograph of one of our test rigs.

We have completed this test on an array of different wetsuit brands with different neoprene types and we will continue to test different models and share the results. You can see the detailed results from the test below. 

The conclusions from this test revealed that:

In this particular test, the SURFDRY improved the drying rate to 80% by 1.5 times (6.7 hours vs 10.2 hours) and to 90% by 1.8 times (8.1 hours vs 14.5 hours).

It should be noted that in this test we used ISURUS wetsuits. These are made from Japanese Yamamoto Limestone Neoprene which is one of the lightest wetsuit fabrics available, with closed-cell technology that minimizes the amount of water that is absorbed and retained by the wetsuit. We’ve found many production suits, especially those fur-lined, absorb 120% of their weight in water.

Ultimately, this is a challenging problem to solve with a huge amount of variables. 

1. Temperature is the Number-One Factor

Temperature fundamentally controls evaporation rate because it:

• Increases the number of water molecules that can escape into vapor.

• Allows air to hold more moisture before saturation..

• Increases internal moisture diffusion toward the surface.

Even at temperatures below boiling, higher heat accelerates evaporation by increasing molecular energy. Source: wtamu.edu

In cold environments, no amount of fan power is enough — low thermal energy limits water molecules’ ability to enter vapor form in the first place. 

This is why hanging a suit out in cold weather often results in very slow or incomplete drying. This article explains more about the ideal set-up for drying.

This aligns with well-established drying physics: warm air holds more moisture and accelerates moisture removal much more than airflow alone. Source: Wikipedia

2. Airflow Matters — Up to a Point

Air movement speeds drying by removing humid air from the fabric surface, replacing it with drier air that can absorb additional moisture.

However — and this is critical — once airflow is sufficient to prevent air saturation at the fabric surface, increasing fan speed beyond that point yields diminishing or zero returns. Source: ResearchGate

From drying studies:

• Drying rate increases with airflow at first.

• Beyond a moderate airflow rate (~0.5–1.0 m/s in textiles), temperature becomes the dominant factor.

• High air velocity does not guarantee proportionally faster internal moisture migration unless temperature is high enough to sustain evaporation. Source: Nature

This supports why low speed, ultra-efficient and ultra-quiet provide sufficient and consistent airflow and adequate access to fresh, un-saturated air and deliver equal or better drying comfort with far less noise and energy consumption.

3. Why Low-Velocity Airflow Can Dry More Efficiently 

Now we know, drying efficiency depends on:

• Air humidity at the fabric surface

• Temperature of the material and surrounding air

At moderate airflow, the air at the surface does not saturate, and moisture continues to evaporate steadily. Driving airflow faster only helps if:

• The air temperature is high enough and

• Moisture can readily migrate to the surface

Once the boundary layer of saturated air is removed, the limiting step becomes internal moisture diffusion within the material, not surface air movement. Higher fan speeds do little to improve that phase, which is why sustained moderate airflow often performs as well or better than high-velocity bursts.

This matches textile drying behaviour: air speed increases drying up to a point, but temperature is the overriding driver, especially for moisture deeper in the material. Source: ResearchGate

In our controlled side-by-side setup with the ISURUS wetsuit:

• Time to 80% dry: ~1.5× faster with SURFDRY.

• Time to 90% dry: ~1.8× faster with SURFDRY.

• Residual moisture: Natural evaporation left ~9% moisture even days later.

This residual moisture — often deep inside folds and seams — is exactly what makes suits feel damp, cold, and uncomfortable. It won’t go away quickly unless the drying process accelerates internal moisture migration and removes it from the fabric entirely.

SURFDRY accelerates moisture removal where natural drying stalls.

• Controlled airflow at effective velocities prevents saturation at the surface without needing high fan power.

• Heat transfer support increases molecular energy available for evaporation.

• Consistent circulation avoids stagnant pockets, unlike a simple breeze or sporadic natural convection.

• The result is faster evaporation and deeper moisture removal.

This aligns with technical drying principles: moisture removal is governed by both energy (temperature) and mass transfer (air circulation). SURFDRY optimises this balance. Source: Ready 2 Respond

We are testing heated versions of SURFDRY to benefit users who:

1. Need even faster turnaround (hours, not days),

2. Don’t have access to warm, dry ambient air,

3. Want reliable drying regardless of environment.

Preliminary results show that temperature + controlled airflow offers the best combination — accelerating drying far beyond what airflow alone can achieve.

Scientific research supports three core truths about drying:

1. Temperature dominates the evaporation process. Cold air cannot dry effectively no matter how fast the air moves. Source: Wikipedia

2. Airflow improves drying only up to the point where saturated adjacent air to the fabric is replaced with fresh. Beyond that, fan speed offers little improvement. Source: ResearchGate

3. Lower-powered, well-engineered airflow systems can be more efficient and comfortable than high-speed fans. Their role is to keep the drying interface open, not to blast air blindly.

SURFDRY incorporates these principles — creating a practical solution grounded in real physics and real data.

The information below is the detailed data that we recorded when conducting this particular test. We captured the weight of the wetsuits at 10 minute intervals.