Understanding Shade Terms

What is “Shade Factor”?

Shade Factor relates to the performance of shade cloth that reflects or absorbs visible and invisible light in the 290nm to 770nm range of the spectrum. Essentially, this is the shade that we can see underneath shade cloth installations on a sunny day.

For example, black has a higher shade factor than yellow. This means that the black shadecloth stops more of the visible light than yellow. This allows designers to choose an appropriate level of shade for different applications. You may require a high level of shade for an outdoor play area or a lesser level of shade for plants in a garden centre.

Shade factor may not necessarily relate to Ultra Violet Radiation (UVR) Block. For example a shadecloth that offers a shade factor of 77 may offer a UVR block of 93%. That is, visible light is still allowed to pass through the fabric but the fabric still absorbs an amount of UVR.

What is “Cover Factor”?

Cover factor is a scientific measurement of the percentage area of the fabric covered by the yarns and fibre.

In other words, the test established cover factor by recording a specific amount of light that passes through the gaps in the fabric. The cover factor depends on the construction of the fabric incorporating; yarn density, the type of weave and the profile of the yarn. Cover factor is not a measure of the fabric weight. Nor is it based on fabric weight. A light-weight fabric can still have a high cover factor.

According to the Australian Standard AS 4174 , 1994 Synthetic Shadecloth, cover factor is primarily used to classify the shadecloth into three categories heavy, medium and light.

Cover Factor varies between different brands and types of shadecloth. Cover Factor heavily depends on the type of construction and colour of the fabric. Cover factor should be considered with the other test data recorded according to the Australian Standard for Synthetic Shadecloth AS 4174-1994

What is “% UVR Block”?

Percentage (%) UVR block relates to the performance of the shadecloth that reflect or absorb incident Ultra Violet Radiation (UVR) within the 290nm to 400nm range of the spectrum. This includes UV-A radiation (315nm to 400nm) and UV-B radiation (280nm to 315nm).

For example, Synthesis Commercial 95 Aquatic Blue shadecloth has a 94.2% UVR block which means that in laboratory test conditions ~ 94% of incident Ultra Violet Radiation (290nm to 400nm) is absorbed or reflected by the shadecloth.

Research worldwide has shown that mainly UV-B, and to a lesser extent UV-A, radiation is harmful to humans and often causes sunburn. Additionally, chronic exposure to UVR has shown a relationship to increased rates of skin cancer. Therefore, the percentage of UVR block is an important factor when selecting shadecloth designed to protect people.

The higher the percentage UVR block, the better the shadecloth protects against Ultra Violet Radiation within the 290nm to 400nm range of the spectrum.

UVR Block varies between different brands and types of shadecloth. Long Term UVR Block heavily depends on the construction and more importantly the quality of the UV stabilizer in the material of the shadecloth. Because the shadecloth actually absorbs some of the UVR, a shadecloth with less UV stabilizer may break-down, or fail in sunlight faster than other fabrics.

This is the one reason why Australian Shade Wholesalers only offer Shadecloth with a minimum 10 year warranty against UV Degradation.

What is a “UPF Rating”?

The UPF (Ultraviolet Protection Factor) rating indicates how effective a fabric is at blocking out solar ultraviolet radiation.

This testing is performed by the “Australian Radiation Protection and Nuclear Safety Agency” (www.arpansa.gov.au) according to the Australian to the Australian / New Zealand standard AS/NZS4399.

UPF ratings range from 15 to 50 with higher ratings indicating more effective blocking and therefore better protection for the wearer of a garment made from the fabric. Fabrics that test higher than UPF 50 are rated as UPF 50+. If a fabric rates a UPF of below 15, the Calculated UPF result is shown.

Factors that contribute to a UPF Rating

  • Composition of the yarns (cotton, polyester, etc)
  • Tightness of the weave or knit (tighter improves the rating)
  • Colour (darker colours are generally better)
  • Stretch (more stretch lowers the rating)
  • Moisture (many fabrics have lower ratings when wet)
  • Condition (worn and faded garments may have reduced ratings)
  • Finishing (some fabrics are treated with UV absorbing chemicals)

What does the UPF Rating number really mean?

A UPF rating number can also be assigned to a certain protection category depending on how much UV radiation they block out. The below table shows the rating system

UPF Ratings and Protection Categories

UPF Rating Protection Category % UV radiation Blocked
15, 20 Good 93.3 to 95.9
25, 30, 35 Very Good 96.0 to 97.4
40, 45, 50, 50+ Excellent 97.5 or more
It is vitally important to block ultraviolet radiation as over-exposure to solar ultraviolet radiation (UV radiation) can cause sunburn, skin damage and an increased risk of developing skin cancer.

* Note: This information is supplied in good faith based on information gathered from various shade cloth manufacturers. MJ Sails takes no responsibility for any technical advice given.