Adhesives have earned a place in the signmaking world as an accepted alternative to welding and mechanical fasteners. Adhesives manufacturers traditionally faced a hard sell to the sign industry. But now, structural adhesives are more widely used, and their benefits are becoming more apparent.
Structural-adhesives manufacturers tout their products as being just as strong — or stronger — than mechanical fastening or welding for the assembly of such sign types as channel letters, cabinet signs, post-and-panel signs and others. $image1
Tom Repczynski, national sales manager for Adhesives Engineering and Supply Inc. (Seabrook, NH), which produces the Extreme Adhesives brand, recommends the family of methyl methacrylates, which are modified acrylic adhesives, for sign assembly. The 1:1 ratio product mixes two components automatically when they come out of the static mixer. Repczynski said it’s difficult to inaccurately mix it.
The company’s industrial adhesives can bond cement, ceramic, metal, plastic, wood and more — anything but glass and rubber, Repczynski said.
To determine the appropriate product for your signshop’s job, Repczynski says to consider project parts’ sizes and the timeframe in which they need to work. Work time greatly impacts adhesive selection, because various adhesives in the same product family cure at different times.Advertisement
For a small project, you might only need a product with a five-minute cure time, but for a 4 x 8-ft. sign, you’ll need more work time before the product cures.
|1983| (Cary, NC) offers various structural adhesives, including cyanoacrylates (a Super Glue-type product), urethanes, epoxies and acrylics. The acrylics most commonly are used to bond signage parts, said Alan Hawkes, Eastern regional sales manager for Lord Corp’s industrial assembly and components group.
Chad Hogancamp, industrial adhesives manager for IPS Corp. (Gardena, CA), said the company manufactures fast-acting, single-component, solvent cements that chemically fuse plastics, plus structural adhesives that bond metal to metal or metal to plastic. The longstanding, one-component product comes in an applicator syringe.
The more recently introduced two-component structural adhesive requires no hand mixing. A dispenser gun mixes it properly in the nozzle tip, he said.
Adhesives vs. fasteners
Hawkes said a strong, structural adhesive offers distinct advantages because it evenly distributes the stress on the substrate, joins complex parts and provides a smooth, invisible finish on the sign substrate’s surface. An adhesive’s bond also reduces vibrations, works well with thin metals, prevents corrosion and acts as a sealant, plus it requires little finishing and application training. It does require some time to cure before it’s fully bonded, and it can’t be inspected — or pulled apart, if needed — once complete.Advertisement
Signmakers still incorporate welding and mechanical fasteners, but adhesives manufacturers say that adhesives were first investigated for use in the sign industry in the 1980s because users sought a more "invisible" assembly method.
Though mechanical fasteners can be easily inspected once installed, and replaced if needed, each rivet or screw concentrates stress on the substrate at that joint. A hole drilled into the material could cause a leak or loosen it. Plus, the fastener is typically visible on the completed sign and difficult to paint or hide, Repczynski said.
Welding, while typically less visible than fastening, can distort or heat warp the metal and weaken the alloys. It can burn off galvanized metal’s corrosion protection. It often requires finishing once joined. However, welding provides a strong, immediate connection, without any waiting, and it’s readily accepted in the sign industry.
Adhesives reduce labor time and cost compared to welding, which requires skilled labor and quite a bit of energy.
"It’s easier to train someone to use an adhesive than to train them to weld," Repczynski said.
He said adhesives can be sanded, painted or drilled. Many of Extreme Adhesives’ users powdercoat over the adhesive bond.Advertisement
Structural adhesives can bond dissimilar substrates. The adhesives are flexible, so they can accommodate dissimilar substrates, such as plastic and aluminum, which expand at different rates in summer heat.
"The adhesive is flexible enough so that it won’t crack with the different expansion rates of the substrates," Repczynski said.
Because adhesives chemically fuse two substrates, the bond is unbreakable, unless you want to break the substrate. Therefore, the adhesive bond can withstand any outdoor environment as long as the substrate holds up, Hogancamp said.
Mark Wilson, materials director for Mandeville Signs (Lincoln, RI), a commercial/electric sign manufacturer, said the shop uses adhesives for sign assembly daily. They also use mechanical fasteners and welding. The company sign designer determines the best attachment method for each specific project.
Wilson said they use Extreme Adhesives’ black product, because the adhesive doesn’t transmit any light. Sometimes they use adhesives atop the weld to reinforce the connection, he said.
"We like the adhesives, because if you weld, you get the heat marks and have to work to hide them," Wilson said. "But with adhesives, you don’t have to worry about that."
Approximately five years ago, quality adhesives were available for a single use.
"There were great adhesives for plastic bonders, but if you wanted to use it on steel or aluminum, you’d have to get a completely different adhesive that was much better on metal," Repczynski said. "Now, we’re offering an adhesive that works on various substrates: stone, metal, plastic, ceramic, wood, etc."
Hogancamp notes that, in the last five years, more types of plastics have become available for sign construction. He said IPS continually tests its adhesives to ensure they work with the different materials end-users need.
Hawkes said adhesives, in recent years, have gained acceptance in the sign industry. He also said there’s more competition now than 10 years ago.
"Years ago, we used to have to convince people, but now people accept that adhesives have a place in sign bonding," Hawkes said.
Manufacturers of Sign-Assembly Adhesives
(800) 888-4583, (603) 473-3070
(800) 933-8266, (978) 777-1100
Rocky Hill, CT
(800) 562-8483, (860) 571-5100)
(877) 477-4583, (310) 516-7013
(877) 275-5673, (919) 468-5980
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