Not Really but Here's the Skinny
by Christian Hazel
Anytime you can put ammunition on an expense report you know your job kicks ass. We fry lots of brain cells and guzzle way too much coffee in an effort to dream up a new ways of testing and evaluating the products that cross our paths. When faced with the task of dissecting innumerable polyurethane bedliner facts, we thought you'd slip into a coma at a blahbity-blah snorefest. So, in typical 4-Wheel & Off-Road fashion, we not only spoke with the top minds in the spray-in bedliner industry to get the lowdown on materials, application techniques, and durability factors, we braved 114-degree heat and a few errant dust devils to get medieval on a few samples.
Polyurethane is very flexible and soft. While this softness prevents items from slipping around on a polyurethane liner, the relatively low tensile strength means a higher possibility that the liner may get gouged.
Polyurea is less flexible and harder. It has a very high tensile strength and resists abrasion and gouging, but its harder surface allows items to slip around more easily.
Poly hybrids combine polyurethane with polyurea, Kevlar, or other chemicals in an effort to provide the best characteristics without compromise. Aggregate such as sand, rubber, or other particles may also be added for texture and slip resistance.
It's generally agreed by most manufacturers that the best compromise among puncture resistance, increased pliability, and reduced weight comes from a 1/8 to 1/4 inch-thick application on horizontal surfaces and a 1/8 inch-thick application on vertical surfaces. Any thicker and you're often just adding weight.
Poly liners bond to the surface mechanically rather than chemically. That means they need tiny grooves and ridges on which to grip. That's why the ideal prep work for most of the liners simply involves sanding and thorough cleaning of the area. However, while polyurea is 100 percent hydrophobic (able to be sprayed directly onto ice or water), polyurethane and poly hybrids aren't, so you should never have a vehicle sprayed after it has been in the rain. The surface must be completely dry unless a polyurea is being applied.
There's high and low pressure and hot and cold applications, although these terms can be misleading. First, low pressure generally gives the applicator more control over the texture. Since many liners don't use an aggregate and the nonslip surface is developed with the application gun, this is important. Second, "hot" and "cold" are misnomers since liner chemicals have an exothermic reaction when they contact each other after leaving the gun, creating their own heat. In both hot and cold applications, the chemicals reach about 230 degrees F. However, in a heated application, the chemicals are brought to 130-140 degrees F before reaching the gun nozzle.
Low-pressure, cold application results in a softer, more flexible product. High-pressure, hot application results in a harder, less flexible product.
Drying and Curing Time
Before you touch the product, it must be dry. Before you can safely transport a load on your new liner, it must be cured. Cold applications will dry in 20-25 seconds, while hot applications take just 3-5 seconds. Hot applications may be the ticket if you need to spray upside down, such as onto a ceiling. Curing time for almost all spray-ins is 24 hours.
Resistance to Fading
In a nutshell, pretty much every product will fade eventually. Some companies add a UV inhibitor to their product and others may spray one on as a topcoat, but it's just buying time. Accept it.
Since the final product is heavily dependent upon the prep work and application, most companies offer warranties through their installers. That is, your warranty will be honored at the place that did the prep work and sprayed your rig.