Our external blind fabrics are high-performance materials designed to provide both a functional and decorative role, however, despite meeting the highest European standards and laboratory tests, they can only be manufactured to a limited degree of perfection even with today’s state of the art machinery.
Waviness and rippling occurs both around the seams (where the panels of fabric are joined – dimout fabric; horizontal joins every 2.5m or blockout fabric; vertical joins every 1.2m) and along the side hems (where the fabric is folded on the sides on external roof blinds or locked into side guides on external roller blinds) due to the arrangement of the made-up external blind fabric, with double layers/thicknesses of material where the fabric is joined (seams) and where it is folded (side hems). This results in the fabric assuming two different diameters around the rollertube.
The tension the fabric is under causes the areas where there are double thicknesses of material (seam, side hems) to press down harder on each other resulting in waviness and rippling immediately adjacent to the seams/side hems. This effect also occurs in the centre of the panel when water is allowed to gather on the fabric on external roof blinds forming a trough of water in the material, along with the use of external blinds in windy conditions, which puts additional pressure and strain on the fabric seams and hems.