Greenhouse and Conservatory Applications

FSI Coating Technologies’ non-yellowing, optically clear, anti-fog controls condensation, providing a superior water sheeting surface on greenhouses and conservatories. Anti-fog coated film also helps to control light transmission and enhance plant growth conditions. In greenhouse applications, the advantage of making the film hydrophilic with anti-fog additives is to migrate water to the surface so water sheets off the film, removing all traces of fog.

Benefits of condensation control in a greenhouse include:

  • More light transmission (15-50%)
  • Higher crop yields, quality, and commercial value
  • Earlier harvesting
  • Fewer diseases and reduced need for pesticides

Why is anti-fog coated film beneficial and how does it work?

With condensation, water can drop from the film onto plants, causing spots which can damage and encourage disease. Drops of water on the film surface can also attract additional sunlight which may increase the risk of scorching plants. Discrete water droplets on the surface can also reflect light away from the greenhouse and reduce light transmission by as much as 50%, also increasing the incident rate of certain diseases, compromising plant quality and growth.

Anti-fog coated film contains additives that alters the surface tension of the film, and encourages water to condense not as droplets but to create a water sheeting effect. As a result, water flows off as a very thin film layer down the slope into the gutters instead of remaining on the greenhouse in a beaded droplet. This anti-fog or anti-drip effect occurs over time and environmental conditions.

Water can also condense on the film surface if there is moisture in the greenhouse atmosphere, and the outside temperature is cold enough. In humid environments, fogging in the form of small droplets commonly occurs on plastics due to temperature differences inside and the plastic greenhouse enclosure. Condensation increases with higher relative humidity and can be further influenced by the plants which transfer water vapor from the soil to the air through their leaves. Fog formation can lead to a reduction of transparency and light transmission, resulting in burning plant tissues from the lensing effects of large water droplets. Small drops grow in size and begin to drip increasing to the point of causing plant damage, especially to seedlings. These fog droplets form from the difference in surface tension from the polar water droplet and non-polar polymer surface.

Additional ventilation or heating may be necessary to remove moisture and misting from the greenhouse by bringing in warmer air from the outside. Anti-fog films are usually made from grades of polyethylene which retain heat well in a greenhouse. There will also be a temperature lift because of the increased light transmitted, the water layer on the film surface also adds to the heat retaining properties.