Skip to main content

Ultraviolet (UV) light is a component of sunlight that is responsible for many of the visible and non-visible effects of the sun’s rays. UV light has many applications in industry and everyday life, but it can also have a degrading effect on plastic materials. 

This can be a concern for manufacturers of bulk bags, which use woven tapes of polypropylene to create a strong and durable fabric for the bulk bags. Custom Bulk Bags is a major manufacturer and supplier of bulk bags in South Africa. 

We produce up to 3.5 million bulk bags per year, all of which have a minimum safety factor rating of 5:1. Our products can safely hold between 500kg and two tonnes of material per bag, depending on your specifications. We also offer numerous optional extras, including UV coatings that will extend the shelf life of your bulk bags. We mitigate some of these effects by adding a UV component into the masterbatch when extruding.

Use cases for sand bulk bags

How bulk bags are made

Bulk bags are made up of woven tapes of polypropylene, a thermoplastic polymer that is widely used in the manufacturing industry due to its durability, strength and cost-effectiveness. While polypropylene is renowned for its resistance to many chemicals and solvents, prolonged exposure to sunlight and UV light can have a degrading effect on the material. 

This is because UV light causes the molecular structure of polypropylene to break down, leading to a weakening of the material, loss of elasticity and eventual cracking and breaking. This is an obvious safety concern for packaging products that are designed to hold massive loads.

White bulk bags filled with sand

Rate of degradation caused by UV light

The rate of polypropylene degradation depends on several factors, including the intensity and duration of UV exposure, temperature and humidity. However, on average, bulk bag fabric made from polypropylene tapes can start to degrade within three to six months of constant exposure to sunlight. 

This could be reduced slightly in hot and humid climates, such as coastal regions of South Africa, where annual sunlight levels are high and daily temperatures can reach over 30°C. Once the fabric becomes brittle and starts to break, it is no longer safe to use for its intended purpose.

How UV coatings help

To mitigate these adverse effects, UV coatings are used to protect bulk bags from UV rays and prolong the longevity of the packaging product. UV coatings are a cost-effective way of ensuring bags last as long as possible. These coatings can extend the lifespan of bulk bags by up to 50%, depending on usage and environmental factors. 

UV-resistant coatings protect bulk bags by providing an extra layer that acts as a barrier between the UV rays and the material. These coatings reflect the UV rays, rather than allowing them to penetrate and degrade the polypropylene tapes.

Bulk bags being lifted off a trailer by a forklift

Working with a reliable bulk bag manufacturer

As a leading manufacturer and supplier of bulk bags in South Africa, Custom Bulk Bags understands the importance of UV coatings to ensure the safety and longevity of our products for local customers. We offer bulk bags with UV coatings, depending on the customer’s specific requirements. 

Our highly experienced team can assist customers with selecting the right optional extras for their bulk bags, taking into account various factors such as product type, storage conditions and the expected lifespan of the bags. Without proper protection, bulk bags can begin to degrade within three to six months of constant exposure to sunlight. 

Regular inspections are required for bulk bags that sit in storage for extended periods of time. If you need any advice or guidance with your specification and ordering of bulk bags, then our team will happily assist. For more information about our bulk bags or to get advice on the ideal design specifications, please contact us today.


Custom Bulk Bags is a leading South African manufacturer of woven polypropylene bags for various industries, such as mining, chemicals and food. We are able to produce over 3.5-million bulk bags per year, keeping our customers in stock at all times. Our bags adhere to the highest levels of quality as a result of our stringent in-house testing and quality control programmes.

Custom Bulk Bags holds ISO 9001 certification and we currently have a number of UN-certified designs. We are a Level 2 B-BBEE manufacturer and supplier and fall under the ownership structure of Deneb Investments Limited. For more information on our products, contact Follow us on Facebook, LinkedIn and Instagram for our latest news and industry insights.