Tutorial: Welding Banners and Tarps by Hand

Welding fabrics by hand is an easy and inexpensive way to complete small jobs, build prototypes, or complete repairs either in the shop or the field. 

You will need:

• Leister hot air hand tool – TRIAC ST recommended
• Wide slot nozzle – 40 mm is the most commonly used
• Silicon pressure roller – of matching width
• Weldable fabric – most common is PVC (vinyl)
• Flat, sturdy surface to weld on
• Tape to secure fabric
• Seam probe for testing – a small flat-head screwdriver works well

Instructions:

1. Attach your nozzle to the hot air tool, turn on and bring up to temperature.
   Further reading:
   • Why you Can’t Measure Air Temperature with a Laser IR Gun and a Simple, Effective Alternative
   • Choosing Welding Parameters for Industrial Fabrics
2. Perform a test weld using scrap material; allow your weld to cool fully and perform a rip test by attempting to tear the two pieces of material apart. If you can see the scrim of the material, the weld is good.
   Further reading:
   • How to: Thermoplastic Membrane Test Welds
3. Ensure material surfaces are clean and free from contaminants such as moisture and dirt.
4. Secure your materials to a flat, stable surface with tape, making sure they are flat and taut; ensure any graphics are properly aligned. The material overlap should be approximately the width of your nozzle.
5. Begin welding
   1. Insert nozzle at an angle between the overlapped material
   2. Place pressure roller on top piece of material, close to nozzle and apply pressure in a back-and-forth rolling motion
   3. Move nozzle and roller simultaneously along the overlap until weld is complete
6. Allow the weld to cool complete.
7. Run a seam probe or flat-head screwdriver along the edge of the weld to test for gaps or voids, re-welding areas if necessary.

Originally published: 9/15/2014