How to Read a Shade Net Specification

A 120 g/m² net does not necessarily cast more shade than one weighing 90 g/m². Fabric weight measures mass per unit area. Shade also depends on the mesh, the yarn and how light passes through them. Start by deciding what the net needs to do, then compare the measurements that describe that job.

Check what the percentage measures

Find out whether the manufacturer specifies the light blocked or the light transmitted. A 40% shade rating corresponds to roughly 60% transmission when both figures describe the same measurement under the same conditions. A visible-light reading does not automatically tell you how much photosynthetically active radiation (PAR), solar energy or UV passes through.

If two datasheets list 40% but use different methods, ask for the test method, the measured waveband and the tolerance. In a greenhouse, what matters is the light that reaches the crop after passing through the net and the glazing. Our greenhouse shade guide explains how to check that on site.

Mesh, strength and durability answer different questions

• How open is the mesh? Ask for the opening dimensions in both directions or the porosity. Shade netting and insect screens serve different purposes. The FAO notes that thread diameter and accumulated dirt also affect how screens perform in a greenhouse.
• How does it behave under load? Compare tensile strength in both directions using the same test method and units. For a net exposed to wind, check the edges, seams and fixings as well. A fabric test covers only part of the installed system.
• What does the warranty cover? Check the installation, exposure and maintenance conditions. UV stabilisation concerns the life of the yarn. UV protection for the space below requires a separate measurement.

Compare two quotes side by side

For each quote, record the shade or transmission rating and test method, weight, mesh opening, strength in both directions and installation requirements. Ask for a sample or test report if the deciding measurement is missing. For permanent fabric on an exposed structure, check the allowable loads and the fixing instructions separately.

The archived TOTAL nets: Cool & Chill page shows how one fabric was used across several applications. Treat it as a historical example and use a current datasheet for a purchase decision.

Source: FAO, Good Agricultural Practices for Greenhouse Vegetable Crops.