Copper Fireplace

Something SPecial

A fireplace like this certainly isn’t something you see every day. When Will at Outdoor Space Design sent us the concept sketches and told us the vision he and his client had, we took a long hard look at what we thought was possible. We were tasked with making a fireplace that was all copper, remained cool to the touch, and left with a natural finish so it could age naturally.

Those of you familiar with copper may already know what a difficult set of parameters this was going to be. Copper is not very strong, and it’s quite soft. Not only that, it is a very good conductor of heat. To achieve this design intent, many hours of careful planning took place so every element could come together into something spectacular. This project inspired my love of copper! I interviewed Sean and David about the project, here’s what they had to say about it:

David had the first shift on this project. Sending sketches back and forth with Will and doing a ton of material science research, eventually he settled on a plan he was confident in. Building a stainless steel structure beneath the copper would serve to provide the strength and stiffness this fireplace would need, and would also provide more thermal mass to help displace heat from the fire and dissipate it so it could remain safe to touch. Using this material also side stepped around concerns of a heat resistant finish. To keep a clean copper appearance, the copper would need to be plug brazed to the stainless steel and the entire structure would have to be built inside out. To get the proportions perfect and keep all the lines clean, the stainless steel was water jet cut and all the pieces came ready to assemble, slowly and painstakingly.

Sean did all the initial tig brazing, and did all the difficult process development work of identifying the issues we were likely to face and how we would adapt. Using helium as the shielding gas, we were able to put more heat into the work making it easier to work with. Copper displaces heat very quickly and with our modest equipment, we needed all the heat we could get to keep the workpiece hot enough to work with. We worried we may need to heat the parts with propane before we could begin welding. Luckily that wasn’t necessary and we didn’t have to work on a ripping hot project the entire time. Brazing copper to stainless steel is a unique challenge that we are unlikely to face again. Though copper and stainless steel have fairly similar coefficients of thermal expansion, they heated very disproportionately which made brazing difficult, and fixturing our parts in place was also a battle as the copper wanted to distort against the cooler stainless steel.

Each and every piece of copper was formed by hand and fit to the structure. This was painstaking work that required a fine touch and a ton of patience. Every time the copper was heated the piece needed to be gently tapped town to avoid bubbling and warpage as the copper tried to separate from the stainless steel. By the end of the project the team had learned a few dozen tricks that they’ll likely never use again. As it all crawled to the finished, the surface was lightly sanded to brighten up the copper to allow it to age evenly and naturally. We had the pleasure of making a visit almost a year later to see how the copper had turned to a nice brown. Someday it will develop the iconic pastel green tones that copper is known for.

This project challenged our team in a way that few projects do. We learned so much along the way and got to build a truly one of a kind piece that we will be proud of forever.