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Bulk bags, also known as flexible intermediate bulk containers (FIBCs), are a strong, durable and highly versatile solution for packaging and transporting large quantities of material. They are commonly used in the mining, agriculture, construction and chemical industries to transport and store raw materials, by-products and waste. FIBCs can be fitted with an inner liner that can improve their functionality and effectiveness in a number of ways.

Custom Bulk Bags is a manufacturer and supplier of FIBCs to a number of South African industries. We can produce up to 3.5 million bulk bags per year. These come in a variety of sizes and weight limits, but all of our FIBCs have a minimum safety factor of 5:1. These bulk bags can also be ordered with a number of optional extras, including inner liners.

Properties of inner liners

Why would a company want an extra inner liner inside their bulk bags? These optional extras are sometimes needed as a moisture, oxygen or chemical barrier that protects the product stored within the bag. In some cases, the inner liner can also improve resistance to static electricity.

  1. Moisture barrier – Some materials need to be kept dry as any moisture will alter its chemical composition or spoil the material completely. Water-soluble products and fine powders are the perfect examples of when to use an inner liner. Sugar, cement powder and fertilizer are three such products that require a bulk bag liner. Any water moisture would dissolve or set these powdery substances.
  1. Oxygen barrier – The woven polypropylene fabric of a bulk bag is not airtight, so sometimes an inner liner is required to keep certain products sealed from the atmosphere. Some chemicals react to oxygen in the air, so a plastic sheet is fitted inside the bulk bag to prevent this from happening.
  1. Chemical barrier – As above, some materials can react to certain chemicals when they come into contact with one another. The plastic inner liner acts as an inert barrier that prevents chemicals from mixing. The plastic is a stable compound that offers better resistance to some harsh chemicals, so companies working with acids, bases, fertilizers and pharmaceutical products will opt for an inner liner.
  1. Resistance to static electricity – Flammable materials pose a large threat where static electricity could be involved. Any spark between the bulk bag and the floor or equipment could ignite the material and destroy a warehouse. An inner liner helps to insulate the material from any static discharges and acts as a safety device against fire hazards. 

Bulk bag liners can be extremely useful in a variety of situations. In addition, they can help to improve the longevity of a product and maximise safety when handling certain materials. These are advantageous qualities to many companies. Before placing an order of bulk bags, speak to your supplier about possible optional extras, including the need for inner liners. For more information about our bulk bags, 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 3 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 for our latest news and industry insights.