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There are many different components that go into making a bulk bag and each one has a different purpose. One of the most overlooked aspects is the type of hem used during manufacturing. The type of hem chosen can have a big effect on not only the strength of the bag but also sifting of material out of the bag – especially if the bags are intended to be stacked on top of each other. We will explore the many hem options below in detail to help determine which one might be best for your application.

Outside Folded Hem

The Outside folded Hem is the most common type of hem used in the construction of bulk bags. This hem is also commonly referred to as the “butterfly fold” due to the pieces of fabric on the outside being able to be pulled up, creating a butterfly wing effect. This hem consists of the two pieces of fabric being put together and the edges on the bag are folded to the outside of each piece, then sewn. This hem provides adequate strength and has limited risk as far as missing the desired hem length. For most applications this is the best option.

Inside Folded Hem

The Inside folded Hem is another very common option and is also referred to as the prayer fold. This is because it resembles when you put your hands together in a prayer position and curl your fingers inward. The Inside Hem is made by putting the two pieces of fabric together then folding the ends in between the two pieces. This hem is another very common type of hem but does present the risk of missing the hem during sewing due to not being able to see the ends of the fabric. This hem may allow the bag to pass through quality tests, but has the potential of pulling away from the stitch after being filled with product.

J-Fold Hem

The J-Fold Hem is another type of hem commonly used in the construction of bulk bags. This hem gets its name from the J like appearance where both pieces of fabric can only be grabbed on one side of the stitching. It is made by taking both pieces of fabric and folding them to one side together. This hem is commonly used in situations where the material has a high chance of sifting when sift proofing may not be used or does not make the stitch tight enough. This hem has the highest degree of risk due to not being able to see where the second piece of fabric is during sewing, which could leave small areas of missed stitching however may be necessary to give the highest degree of sift proofing.

Sulzer Hem

The last type of hem that we will talk about is the Sulzer Hem. The Sulzer hem can only be made with Sulzer fabric and requires specialized equipment. It has a higher tape count at the ends of the fabric where they will be sewn, making the area more dense and stronger than standard fabric. The stronger fabric allows for the removal of the hem due to the added strength of the fabric. It is made by sticking 2 pieces of fabric together and sewing them with no fold. This hem provides the least amount of risk due to only having to stitch together 2 layers of fabric.

As you can tell by the varying hem styles, the type of hemming used on your bags can have a big effect on the performance of the bag and may alter the perfect reproducibility of the bag. If you have problems with your bags and believe that it may be due to the type of hem being used, contact your Global-Pak experts to help you decide which hem is correct for your situation.