01. What is the relationship between light transmission and shade cloth?
To answer this question it is easiest if we go back to basics with the fundamentals of light.
Light is part of the electromagnetic spectrum and this is measured in wavelengths using a nanometre (nm) or 1 billionth of a metre. The general rule is the shorter the wavelength the more energy.
Humans can see visible light which is between 400 nm and ~730 nm. We cannot see UV (ultraviolet) light which is between 290 nm and 400 nm.
The solar transmission through shade cloth is significantly reduced across all wavelengths and is dependent on colour. All colours reduce UV transmission, which is the cause of sunburn and skin cancer, by at least 90% and up to 95%. This is measured by UVR block. Heat or infrared is also significantly reduced, particularly by the dark colours which reduce the heat transmission by up to 90%. Shade cloth provides excellent protection against the harsh effects of the sun.
02. What is a UV block and how is it determined?
Polyfab shade cloth has been designed to block out UV (ultraviolet) light to varying degrees depending on the range.
To determine the UV block out amount, a test is required by the Australian Standard AS4174 – Synthetic Shade Cloth. This test measures the amount of UV light (290 nm – 400 nm) that is blocked by the shade cloth. This is either via reflection or absorption.
UV block is the inverse of UV transmission e.g. 95% UV block = 5% UV transmission.
03. What is cover factor?
To determine the cover factor of a shade cloth a test is required by the Australian Standard AS4174 – Synthetic Shade Cloth.
This test determines the percentage area of the fabric covered by the yarns and fibre of the cloth. It is affected by the density of the yarn, profile and type of weave. Please Note: it is not affected by the weight of the fabric.
04. What is shade factor?
To determine the shade factor of a shade cloth a test is required by the Australian Standard AS4174 – Synthetic Shade Cloth.
This test defines the amount of visible and invisible incident light that is blocked by a shade cloth.
Shade factor is the inverse of average transmission e.g. 70% average transmission = 30% shade factor.
