Shade Sails Definitions

Shade Sails terms might sound too jargonistic and might just cause confusion. We aim to aid you in making the right purchasing decisions. So to help you get through these terms with much better understanding, here are some terms and their definitions.

What is “Shade Factor”?

Shade Factor evaluates the capability of a shadecloth to reflect or absorb visible and invisible light ranging from 290nm to 770nm of the light spectrum. This is the shade that we can observe underneath a shadecloth that’s placed under the sun.

A black shadecloth has a higher shade factor than that of a green shade cloth. That means it stops more visible lights than the green one. This allows you to choose a shade that is appropriate for the location. You may want to have a shadecloth with higher level of shade factor in open areas like an outdoor play area and prefer lower level of shade factor for plants in a garden.

Shade Factor may not necessarily relate to Ultra Violet Radiation (UVR) blocking. It could have a lower level of shade factor of 77 so still allow light to pass through and yet the shadecloth can absorbs a good amount of UVR with a UVR block of 93%.

What is “Cover Factor”?

Cover Factor is a scientific calculation of the percentage area of the fabric that’s covered by the fibre and the yarns. In order to get the results, a test is conducted by recording a specific amount of light that passes through the gaps in the fabric. Cover factor depends on the construction of the fabric including the profile and density of the yarn and the type of weave used, as well as the colour of the fabric. It does not matter how heavy or light the fabric weighs. It could be a lightweight fabric but still can give a high level of cover factor.

Cover Factor is primarily used to classify the shadecloth into Heavy, Medium or Light category. This is according to the Australian Standard AS 4174, 1994 Synthetic Shadecloth. Cover Factors may vary between different types of shadecloth through different brands. It should be considered with other test data according to the Australian Standard for Synthetic Shadecloth AS 4174-1994

Abshade Black Square 5m x 5m Shade Sail from Gazebos Australia

What is “UVR Block”?

Percentage (%) UVR Block evaluates the capability of the shadecloth to reflect and absorb incident Ultra Violet Radiation (UVR) within the 290nm to 400nm range of the spectrum,this includes both the UV-A radiation(315nm to 400nm) and UV-B radiation (280nm to 315nm).

This means that if a commercial shadecloth has a 94% of UVR block, 94% of incident Ultra Violet Radiation (290nm to 400nm) is absorbed and reflected by the shadecloth. That keeps you free and protected from UVR as the shadecloth has absorbed and blocked them.

According to research, mainly UV-B, and to a lesser extend UV-A, radiation is harmful to humans. These often cause sunburns. Constant exposure to UVR can increase possibilities of skin cancer. So it is an important consideration to choose shadecloth that has a higher percentage of UVR block to protect people. The higher the UVR block percentage, the better UVR protection the shadecloth can give.

UVR Block depends heavily on the construction of the fabric and most importantly, the quality of the UV stablilizer of the shadecloth material. The shadecloth with higher percentage of UVR block relatively last longer. While a shadecloth with less UV stabilizer may break down or fail in sunlight because the shadecloth actually absorbs some of these UVR.

UVR Block differs between different types of shadecloth made by different brands. Australian Shade Wholesaler only offers Shadecloth with a minimum of 10 year warranty against UV degradation as shadecloth absorbs UVR, it may break down or fail after some time.

What is a “UPF Rating”?

Image from ARPANSA, Clothing as UVR protection, Page reviewed: 22 February 2012.

UPF stands for Ultraviolet Protection Factor. UPF Ratings gives us an indication of how effectively a fabric is blocking out the solar ultraviolet radiation. This test is performed by the “Australian Radiation Protection and Nuclear Safety Agency”according to the Australian/New Zealand standard AS/NZS4399. 

UPF ratings of 15 to 50 means it more effective in blocking UVR and can better protect the wearer of the fabric/garment. The composition of the yarns whether it is made of cotton, polyester, etc can greatly contribute to a UPF rating.

The following fabric factors can contribute in giving you a much higher UPF rating:

  • Fabrics with tightness, less stretchy
  • Darker coloured fabrics
  • Good fabric condition, not faded and worn out
  • Fabrics that are treated with UV absorbing chemicals
  • Fabrics that are moisture-wicking as many fabrics have lower ratings when wet.

What does the UPF Rating number really mean?

A UPF rating number can be associated to a certain protection category depending on how much UVR it blocks out. You may refer to the following table that shows UPF ratings and categories for you to be guided accordingly.

Table taken from

Take note that over exposure to the sun’s ultraviolet radiations can cause sunburns, skin damages and may promote the risk of developing skin cancer. It is vitally important to use garments and fabrics that gives superior protection from UVR.

Photo courtesy from Flickr by Scottb211