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PetraSlate’s Tour of Evergreen Slate Company Part 2

Petra Slate

Slate Roof TileIn our never ending quest to bring only the finest in slate roof tiles to the Denver market, we recently toured Evergreen Slate Company’s operation in Vermont. The process of turning raw slate into finished roof tiles is intriguing to say the least and should give Denver contractors and architects an appreciation for the slate roofing tile quality and premium pricing over typical asphalt shingles.

Jackhammers Make Life Easier

Watching the modern quarrying operation is infinitely easier than quarrying must have been in the past. While modern heavy equipment can move enormous slabs of slate from the vein the chunks are still far too heavy to be transported far while intact.

This is where jackhammers come in. The impact of this tool is used to fracture the slate slabs along their linear fault lines. Due to the way that the slate was deposited and formed by pressure over time, it is exceedingly strong along one axis and relatively easily fractures on the other. By splitting the cubic slabs into more manageable forms at the quarry, workers start the slate roof tile production from vein to manufacturing.

Processing Slate into Roof Tiles

Slate Tile in DenverNot until the factory do the slate slabs begin to take shape into something useable. The quarried slate is put onto a roller table where it is dimensionally cut by a series of liquid-cooled saw blades. The goal is to make uniformly-dimensioned rectangular blocks of the desired size so that skilled workers can again take advantage of the clean splitting ability of slate to turn this cube into individual roof tiles.

It takes a sure hand and an experienced eye to take a hammer and chisel and split a block of slate into as many as ten tiles of more or less identical thickness. There can be no exaggerating of how critical this step is. Without close uniformity, tiles of varying thickness would also be of varied weight and – durability too, complicating its installation as a roof covering.

The Last Detail—Nail Holes

It took untold millions of years of time and pressure to form the slate. It took explosives and heavy machinery to get it into the form of a slate roof tile. All it takes is one misapplied blow while making the nail holes to utterly ruin all of this effort by fracturing the tile.

Punching a nail hole into a slate roof used to be done manually with a special hammer or a punch. Now a machine ensures the tile is properly supported before impacting it. Still, there are unavoidable losses when working with stone. As much as 15 percent of tiles are wasted at this late stage of the manufacturing process, turning them from a precious product to mere rubble. This “spoilage” also adds to the overall cost of finished slate tiles.

Now finished, the slate roof tiles are color-matched and packaged for transport to PetraSlate, where we offer you the finest slate roof tiles found in America. Contact us for  color samples technical specifications and pricing through our Petraslate Denver showroom, or any of our dozens of distributors around the country.



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