One Hectare of Shade: Drone Application of Sudlac Eclipse F4

Shading a polytunnel is a straightforward job with an awkward problem: getting the product evenly onto a surface that is difficult, slippery and potentially dangerous to work on from above.

The conventional approach, operators on scaffolding or working from raised platforms works, but it comes with costs. Setup time. Roof damage risk. A team of people needed for a job that is ultimately just coating a surface. And on a hot day in May or June, when shading is most urgently needed, it's miserable work.

We were asked to apply Sudlac Eclipse F4 shading compound to a 1-hectare commercial polytunnel site as a trial. The brief was to achieve even coverage across the roof surface, demonstrate that drone application could replace the manual method, and do it without anyone going near the polythene.

View of our drone from a cherry picker.

Why shading matters

Polytunnel temperatures on a UK summer day can climb well above the levels crops prefer. Unshaded tunnels can reach temperatures that cause heat stress, flower drop and reduced fruit set. Shading compounds reduce the solar load entering the structure, bringing internal temperatures down. Research into comparable products consistently shows reductions of up to 5°C in average temperature, with the effect greatest during peak radiation hours.

Beyond the crop, the polythene itself benefits. UV radiation degrades polythene, shortening cover life. Growers who regularly apply shading compounds report meaningful extensions to the functional lifespan of their tunnels with the whitewash layer absorbing and reflecting radiation before it reaches the plastic.

The product: Sudlac Eclipse F4

Eclipse F4 is a temporary shading compound designed specifically for use on polytunnels, glass and polycarbonate structures. It creates an even white coating that reduces light transmission to between 30% and 70%, depending on dilution, and wears away gradually over the season, typically lasting two to four months, without requiring removal. It can be washed off early if weather conditions change unexpectedly.

Unlike shade netting, a coating responds to the roof geometry and follows every curve, leaving no gaps or bridging. It also provides light diffusion rather than pure exclusion, scattered light penetrates the canopy from multiple angles, which can benefit crop photosynthesis compared to a single directional source.

Filling up the drone with more paint.

The application

We applied Eclipse F4 at 600 litres of spray solution per hectare, which falls within the standard range for thorough roof coverage. Application rates for shading compounds by drone typically run between 600 and 800 litres per hectare when full coverage is the objective.

The drone approach to polytunnel shading works on simple geometry: fly parallel passes along the length of the tunnel at low altitude and matched speed, maintaining consistent spray width across the roof. The coverage per pass is uniform, and because each pass is GPS-guided to the same spacing, the overlap is predictable and consistent. There are no hand-applied sections, no areas where a person reached from one side but not the other, and no streaking from uneven pressure.

The alternative is access equipment: scaffolding or raised platforms, a pump, and a two-person team working at height, with setup and takedown either side of the job itself. A drone pass needs none of it. The polythene is never walked on.

The most common source of inconsistent shading is uneven application one stretch applied on a warm morning, another in the afternoon when the product viscosity has shifted, sections applied by different operators with different hand pressure. With a drone, the application conditions and parameters are consistent from the first pass to the last.

Drone application of shading compounds in the UK

Polytunnel shading by drone is still relatively uncommon in the UK, but the case for it is straightforward: it removes the access problem entirely. There is no structure to build around the tunnel, no team on the roof, no damage to the polythene from foot traffic, and no dependency on weather windows that also allow people to work at height safely.

For growers with multiple polytunnel bays, or sites where the tunnel geometry makes manual access genuinely difficult, a drone pass offers a repeatable, scalable solution.

If you grow under cover and shading is part of your seasonal programme, we're happy to discuss whether drone application would suit your site.

Talk to us about your polytunnel