Geoola, F., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, 50250 Bet Dagan, Israel
Kashti, Y., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, 50250 Bet Dagan, Israel
Levi, A., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, 50250 Bet Dagan, Israel
Brickman, R., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, 50250 Bet Dagan, Israel

An experimental model greenhouse was used to investigate the solar radiation transmission and aging of greenhouse cladding materials in general and anti-drop materials in particular. Three types of low-density polyethylene films covered the experimental greenhouse, which consisted of eight identical sections. Comparison of solar radiation transmission of the films, over a period of 3 months showed that in a wet state (under condensation), non-anti-drop films had lower transmissions than in a dry state. Transmission of new anti-drop film was found to be higher in its wet state than dry state. The deterioration of surface-active additives in anti-drop films was studied. Based on relative difference between the dry and wet state transmissivities of materials, a testing method was developed for measuring and quantifying the efficiency and durability (aging) of anti-drop properties. The relative difference in wet and dry state transmissivities of the anti-drop film deteriorated from +4.2% for new material to -15% after 3 months. © 2004 Elsevier Ltd. All rights reserved.