Making good tent fabrics is challenging because it consists of so many different factors that must work optimally together. Many people are fooled into thinking that the quality of the fabric is good as long as the water column is high. We believe that both a high water column, tear strength, choice of seam, and thread are the key behind the best tent fabrics.
The seams are crucial for the quality of a good tent, and having the right seam in the right place is essential. Seams with the greatest stress are sewn with cut stitches according to the shuttle stitch method. Shuttle stitch is the only stitch that does not break if the threads break. Exposed load points are reinforced by the use of a special bridle seam. The plug fasteners have e.g. bridle stitching and inlaid reinforcement. The seams on the tent are laid so that water does not collect at the edge of the seam but easily flows off the fabric without obstacles.
In addition to the well-thought-out placement of seams, we use a stocking-free polyester thread with water-repellent coating. This means we can use a very thin needle which in turn creates a very small hole. Small holes and water-repellent thread prevent water from drawing in through the outer fabric.
The combination of cut stitch and its placement in relation to the poles on the tent gives a waterproof construction.
Seam in bottom cloth
Some manufacturers weld the seam in the bottom fabric, but most of Helsport's tents come with the silicone-treated bottom fabric without welding. We can do this because our sewing methods and thread prevent water penetration. Nevertheless, in some lavvos and tents where it is important that the bottom fabric is fire-retardant, the seams are welded, because the necessary treatment of the fabric is not effective in combination with silicone treatment.
It is important to note that the tear strength only says something about what happens to the fabric when it has been torn. High tear strength prevents the tear from expanding. In a tent context, this will also tell how the textile behaves around seams, rope attachments and the like.
Tear strength is affected by four factors; base material, wire thickness, construction, and coating. The first three factors can be linked directly to the text properties. A strong material, a larger thread thickness, and several elements of reinforcing threads give a proportionally higher tear strength. However, the type of coating also affects the tear strength, although it may be difficult for the naked eye to see.
If you envision the point where the demolition takes place, a rigid coating, e.g. PU, leads to a poor voltage distribution and you will tear over one wire at a time. If, on the other hand, the coating is more elastic, such as the silicone coating, the tension will be distributed over several threads, which gives a considerably higher tear strength.
We test our fabrics in accordance with international standards: ISO 139374. In our Pro and X-Trem tents, we use Helsport Superlight® 1000, which with a tear strength of over 18 kg makes them some of the most durable on the market.
800 mm water column is considered according to the international standard EN 343 as waterproof, but it is not the water column in a new product that is important, but the substance's ability to maintain the water column over time. The water column is measured by subjecting a textile sample to increasing water pressure. The test ends when 3 drops of water have penetrated the fabric.
Initially, an 800 mm water column will be considered a waterproof material, but different uses of the textile require different water columns. For the outer tent, an 800 mm high water column will protect against rain in strong winds, but a higher water column will be needed if you are sitting on the tent base on wet ground.
Helsport has therefore chosen to have a higher water column in the bottom material than in the outer tent. Silicone and PU coatings deteriorate over time, and sunlight, folding and bending lead to a reduction in the water column. It is therefore advisable to start with a water column higher than 800 mm, to ensure the product's long life.