Selecting the Right Keder System for Your Application
The right keder depends on three things: the attachment style, the weave of the jacket fabric, and the weight of the yarn. Keder styles separate into three forms based on attachment method: sewing, single flag (weldable), and double flag.
Sewing Keder
Sewing keder is the simplest of the three to attach: the flag is welded shut, making it easy to sew to a fabric panel. It is a great choice for signs and banners, and also for larger applications such as awnings and canopies.
Note that most sewing thread is not designed for UV resistance, so sewing is not a suitable method where long-term durability against sunlight exposure is a consideration. Special PTFE thread can provide long-term durability.
Single Flag Keder
A single flag attaches with any welding method, including hot air welding, wedge welding, and radio frequency (RF) welding. RF welding creates a stronger bond and improves water tightness and UV resistance. Single flag keder is not appropriate for larger panels with high tensile loads: because the welding occurs on one side only, the weld becomes a single point of failure. That is why single flag keder uses wider 20 mm welds, and why our experts recommend RF-welded single flag keder. Lightweight Structures distributes all keder already RF welded.
Double Flag Keder
Double flag keder is the strongest and most durable style, and it welds properly only with a radio frequency (RF) welder, equipment that can be cost-prohibitive for smaller companies. With both sides of the flag welded to the panel, the weld is no longer a point of failure; the strength of the fabric becomes the only limitation.
Weave Styles
The weave style refers to the way the keder fabric is woven. There are two common weaves:
- Plain weave: the most basic form of weaving. Each weft yarn crosses the fill yarns over and under, and the next weft yarn goes over the fill yarn the previous one went under, and so on.
- Panama weave: a variation in which two adjacent yarns go over and under together, in both the weft and fill directions. The Panama weave stores more yarn per inch woven, giving the fabric greater strength at the same yarn size.
Thread Weight
Fabric strength is measured on the denier or dtex scale. Keder with thicker yarn tends to be stronger and more durable, and it slides better. It usually costs more. Lightweight Structures offers three thread weights: 2000 denier, 1500 denier, and 1000 denier.
Construction and Coating
Construction is the fourth variable. Double coated keder wraps PVC-coated fabric around the core underneath the keder cloth, which shields the cloth from UV and doubles the fabric at the point where the keder wears against the rail. Where a panel already in service has damaged keder, Renew Keder replaces it without an RF welder.
