Maximizing the Metal: Why Not all Metal is Created Part II
This article, by my friend Sharon Thatcher, was originally published in the September 2016 issue of Rural Builder magazine and appears unedited. To continue from last Friday:
THE IMPORTANCE OF PAINT
While paint doesn’t provide any structural value, it certainly does add value to the end product. Unpainted panel still has a big audience, but painted coil is now more popular than ever and it’s what most customers see most clearly.
Dan Knight came up through the steel ranks via the paint industry and he explains the different types of paint.
There are three types of paint systems for metal that are commonly used here in the U.S.:
Polyesters: the least expensive, usually with a 10-year warranty on an exposed application.
“Polyesters are a very good workhorse but typically they don’t have the exterior durability that’s required on the warranted products,” Knight said. “So where you see them is on the low- or non-warranted systems such as interior liner panels, gutters, non-warranted or very low-warranted wall and roofing panels. There is always going to be a market need, some people call it shade-and-shelter. It’s located in the back 40 and it’s not expected to last 40 years.”
SMP (silicone polyesters): The most widely used, averaging a 40-year warranty on the film (but fade and chalk can occur over time).
“It’s basically a more durable exterior grade system. This is the workhorse in the rural builder’s market,” Knight explained. “This is commonly referred to as a 40-year paint system.”
PVDF (Polyvinylidene fluoride – trade names include Kynar and Hylar): the premium paint system, averaging a 25-year warranty, but with the best protection against fade and chalk.
“You see [PVDF] a lot in commercial buildings,” said Knight.
The thickness of the paint is important. The thicker the paint, the better the panel can weather the elements and protect the substrate.
For warranted material, the primer should be a minimum of .2 mils thick and the paint or topcoat at least .8 mils for a total of 1 mil thickness. Like steel, there is a range: for top primer the range is 0.2-0.3 mils; the top paint or coat is 0.7-0.8; and the bottom or backer with primer is 0.5-0.7 mils.
“This is where understanding the supply chain of the paint system is important,” Knight said. “What you have to understand is that the paint warranty only covers three facets:
Chalk: This is a degradation of the resin and the pigments over time. When you rub your hand on the coating, it leaves a white residue.
Fade: the depth of color difference, say when a dark brown paint turns to a light brown.
Film integrity: the ability of the paint to stick to the metal.
“What is interesting, everybody says 40-year warranted paint but [with SMPs] the film integrity is 40 years, the chalk and the fade are 30 years,” Knight said.
In the U.S., the paint warranty comes from the paint company (an Akzo Nobel, a Valspar, a Duracoat) and is held by the company that applies it. No paint warranties are transferable. The paint warranty remains with the fabricator.
When there is a problem, it goes up through the chain to evaluate the cause of the failure and who will take responsibility, including the installer.
All roll formers should have available their agreements with the paint company, with the important facets of that language written into their own agreements as a protection for themselves and their customers.
Confused yet? To builders Knight noted: “I think it’s important to deal with a reputable roll former who has the depth to stand behind their product.”
HANDLE WITH CARE
Once off the production line and on the job site, it’s up to the builder to make sure the panel is handled correctly. Don Switzer offers these job site tips.
Job site storage: “I know you think, well it’s building panels, we can store it outside,” he said, “but building panels are built to be on a building, not to be in a stack … In particular you don’t want water to get between the sheets so it causes the paint to delaminate. The pressure of the stack, and the water forces the water through the paint and makes it delaminate. Once they are on the building, and the water is hitting them, the water is just running off. But when you have the water trapped, that’s where you have a problem.”
Installation: “The key is that you don’t damage the surface,” he said. “The metallic coatings without paint (Galvalume or galvanized) or the metallic coatings with paint are not as hard as the steel substrates beneath those paints. So you want to make sure you don’t compromise the integrity of the painted or metallic surface. Again, once they’re up and they’re not scratched, you don’t have a problem. But if you scratch that product all the way down to the base metal, it’s going to rust because you’ve damaged the barrier placed there to protect it.”
MORE ON WARRANTIES
Stay tuned tomorrow, as I share “the rest of the story”…