After a 50-plus year career in the sheet metal HVAC industry, SNIPS Industry Icon David Daw is chronicling the major historical events that he either took part in or observed. His most recent piece for the April issue of SNIPS eMagazine investigates how developments in CAM and water-based sealants in the 1980s revolutionized the ductwork industry. 

“In the early ‘80s, I learned more about Hardcast, Foster and similar products due to the need for sealing longitudinal seams and transverse joints when not using Ductmate or a Slide-On connector,” he writes. He also describes how a salesman approached him with an adhesive tape primarily for round duct connections that eliminated the need for the labor intensive and messy Hardcast system along with other products the trade referred to generically as: “air-ball and canvas.”  

“While it was a good concept, (at the time) it did not prove out,” he says, continuing:

“Now, because of my work at Gripnail, I knew a lot about petroleum-based solvent adhesives used for duct lining and all the problems associated with them. At the time, the only duct sealers were solvent based too. I like new products. I thought that if a water-based duct sealer proved its mettle in the field, this could be another industry game-changer. I was all in and my initial reaction later proved spot on.  Today, water-based duct sealers control the market, but it’s not only about sealing joints; it’s duct liner too.

It’s been so long that I’m afraid few remember the difficulties with solvent-based adhesives for duct lining – flash fires in the shop’s lining area for one. But it wasn’t only the fire hazard. The use of solvent-based adhesives did not provide the healthiest of environments and it was messy.

There were two types: flammable at “X” amount per gallon and non-flammable at double the price. You know which the contractor preferred. But when using flammable with a welded pin-spotter to attach the pin to the sheet metal, it was not uncommon to see a flash fire flair up. On a side note, one of the big advantages Gripnail had over welded systems: A true mechanical fastener that did not require electricity to secure.

I knew instantly that if water could be used as the medium to cure adhesives used in duct-lining, this would be a game-changer – and a game-changer it was. Those early years of the 1980s proved prescient. By decades end, solvent adhesives were on their way out of the industry forever.”