The last thing you want to do is sell your customer a banner with a shorter flight life than the job requires. If you want the banner to live beyond it’s intended use then you want to seam the edges with something that stands up to the wear and tear of weather, sun, and dust.
What options are available? How does one choose? The most popular seaming options are banner tape, glue, chemical welding, RF welding (heat welding,) and stitches. This article discusses the benefits and disadvantages of each.
For small banners, particularly those needing a quick turn around, banner tape is an excellent choice. It's not permanent so it's not recommended for larger, more weight-bearing banners nor should it be used on outdoor products or those that require longevity. However, it works excellently for event banners that will be used only one time over a short period.
Banner tape requires no special equipment for installation and is applied like any other double-sided tape; requiring no special skills to install.
"There is actually a very distinct difference between a chemical weld and glue. Glue is simply a very sticky product that makes two pieces stick together. Under stress glue can release either from itself or from one of those two surfaces," explains David Wysong, with The Color Spot in Marietta, GA.
Glue forms a distinct layer between the two pieces of banner. Plastics found in the glue, such as epoxy and acrylic, are modified to suit vinyl; however, that modification shortens the lifespan of the glue.
So while it may not stand up to long-term exposure, your customer should be fine under normal conditions short term. The glued banners shorter life span is a good choice for one time events such as grand openings, graduations, and birthdays.
Chemical weld is a solvent that is applied like glue, but offers a more permanent seam. As it suggests, chemical welding instigates chemical fusion and dissolves together the two portions of the banner. You can brush, pour or squirt the various chemical welds onto the vinyl and press the two portions together. For best results use a brush. Cosmetically, the results are similar to a thermal weld and the process doesn't require much skill. Still, there are a few application tricks and safety precautions that go along with them.
Much of the sign industry uses HH-66: more commonly called a bodied adhesive or bodied solvent. When properly applied, tests show HH-66 provides a super strong, waterproof, flexible bond. It is highly resistant to temperature and weather extremes, and is excellent for patching and sealing vinyl, according to the manufacturer.
Wysong goes on to explain, "With a welding solution you literally meld the two surfaces together so that they become one. It’s like the difference between bolting two pieces of metal together versus literally welding them."
A chemical weld may not actually cause sparks like a metal weld, but it too can be dangerous if not handled properly. It contains combustible solvents so keep it well away from any open flame sources and the can tightly sealed when not in use.
Manufacturers recommend using a ventilating device, such as a fan or air mover, when using chemical weld in limited ventilation areas. You can also use an air-purifying NIOSH-recognized respirator. Be sure that your ventilator is not a possible source of ignition. Moreover, these solvents could cause irritation if they come in contact with your bare skin. Manufacturers recommend wearing gloves while applying the weld.
RF Welding or Heat Welding?
RF welding fuses materials together by applying radio frequency energy to the area to be joined. The resulting weld can be as strong as the original materials itself if applied correctly. RF welding is more expensive than chemical welding but it’s incredibly strong in comparison.
In scientific terms, the rapidly alternating electric field generates heat and causes the molecules in the banner material to oscillate and fuse together. At 13-100Mhz electromagnetic field, its typically applied between two metal bars with pressure held during heating and cooling.
Hot air and hot wedge rotary heat sealing are two additional processes used to join materials. Just like they sound, they use heat, speed and pressure to produce a welded seam.
A variety of industrial sewing machines are available, however, the one-needle, unison-feed lockstitch is the most common in use. There are also double-needle, chain-stitch machines that use four thread spools that feed from the unit's top and do not require the bottom bobbin thread to be changed. These are a better choice for companies producing large volumes of work without interruption.
Avoiding ugly, puckered seaming is a primary concern with stitching. Because the feed works in a chewing-like motion, it is possible for the vinyl to gather under the foot and cause unwanted pleats in the hem.
Which of the above methods are best for the task? It would greatly depend on the final use of the product, operating budget, available skills, etc. Taking ones own needs into consideration, the following side-by-side comparison will make choosing a little easier:
(Services offered by The Color Spot are in blue.)
The seam(s) you choose depends on your needs and budget. Banner tape and glues are by far the least expensive methods by which to seam banners. However, RF heat welding and stitching offer the obvious advantage of greater longevity. If you are breaking into bigger jobs that require RF and heat welding but can't afford to shell out the bucks for the gear, you can always outsource this aspect of the project. For outsourced finishing needs, consider calling The Color Spot at 678-385-2188. Your project will be completed on time, guaranteed.