Blackened Spiral Staircase
A contractor was building an addition to a mainline Philadelphia residence. Part of the addition was for a library space on the 2nd floor. The architect had designed a blackened spiral staircase for that area. The clients are well traveled and had inspiration ideas from foreign countries that they wanted incorporated into their spiral stair design.
One concept was for a larger 6” dia center pole, and then to have the wood treads “float” from the center pole to give it more of a modern stair design. A significant challenge with this was how to make the wood treads be 4 sided. We made the top piece of one tread extend to become the bottom part of the next tread. The outside stringer was ¼” plate on edge with no trim, for a very clean and contemporary look. The pickets were then traditional design ½” square solid with classic knuckles. The handrail design was a minimalist 1” round bar. We added an additional handrail on the inside of stair to meet code.
The client had seen a forged knot and tassel detail during their travels that they wanted replicated. To do this forged knot, we started by molding with playdough. Once comfortable with that, we graduated to ½” round bar. Then the ¾” round bar for the final product. For the tassel, we started with 2” round bar hammering it to a pear top shape and upsetting the bottom to create a bell shape. For this we created a custom spring die with a chisel point at the top and bottom. The tassel piece had to be red hot, then it was hammered with a striker and helper to forge the intricate grooves in the tassel.
The next obstacle was that the client desired the entire spiral stair and railing structure to have an antique blackened finish. For context, this spiral stair structure was overall 12 ft high, 6 ft. wide and 6ft deep, thus making this request more challenging. The first step was to blast the entire spiral stair to a white metal. Then, we set it up vertically and sprayed with an oxidizing chemical to blacken the material. After this, the whole structure had to be rubbed down by hand with a scratch pad . Then we placed the stair structure in a large oven and heated it to 150 degrees. We then rubbed renaissance wax over the entire structure to encapsulate the living finish and complete the porject.
The installation was the final challenge as this piece weighed approximately 800 pounds. It was not possible to get any large equipment into the space, so we attached a winch to the ceiling to hoist the stair into its vertical position.
The clients absolutely love their custom crafted spiral stair, and it will be a testimony to their design inspirations in this Philadelphia home for many years to come.