4- Can you weld the seams of my zinc bartop on site?

Ah, this timeless question.  To understand why the answer is “no”, let’s look into the properties of zinc and some great reasons why you do not want to do this.

Zinc melts at 787 degrees Fahrenheit, but can be made semi-liquid at much lower temps.

Another important number to know is max service temperature, or the temperature at which it is safe to use a metal for a prolonged period. Zinc’s Max Service Temperature is 140 degrees.  So, if you do choose zinc as a surface material, be sure to protect counters with trivets or hot pads before placing hot skillets directly from the broiler on them. This is good advice for any surface, so why tempt fate with zinc?

To further explain this common fabrication question concerning Zinc, let’s look at some of the other melting points of post-transition metals, which are generally extremely low:

Tin = 450 Bismuth = 521 Lead = 621 Aluminum =1221

And for fun, some other popular copper alloys:

Brass = 900 Bronze = 950 and Copper = almost 2000

As a comparison, stainless steel melts at 2500 degrees and has a max service temp of 1600 degrees F.

The start of our answer comes back to an understanding of alloys and melt temperatures.

True French bistros are fabricated from Pewter, which is an alloy composed primarily of Tin.  When worked on site, the filler rod is the actual material, which melts at an extremely low temperature, around 450 degrees F. This is just low enough not to affect the wooden core below, and this can be blended perfectly and will age and patina the same as the surrounding metal.

Zinc is a much different story than Tin.  To keep the surface metal intact, a lower melt alloy containing tin is generally used so that the wood below doesn’t ignite, and the relatively thin zinc layer doesn’t vaporize.

If site seams are attempted, what results is a slightly different color metal that takes patina much differently than the zinc metal.  So in reality, it’s not soldered or welded, but rather a hot bead of metal caulk, acting as a filler, is laid between the two pieces.

I don’t recommend this for several reasons, but firstly and foremost,  because it looks awful, and there are better ways to achieve a tight seam.

In recent years, manufacturers have been fabricating tops in increasing lengths to eliminate project seams.

While this seems like a good idea, the larger pieces are more fragile and susceptible to internal failure.  Crating, shipping, and storing these monsters is a monumental task, and installation can take as many as 10 people to maneuver these large tops.

 Tight seams can be achieved at the factory with improved technology and better manufacturing techniques.

Another reason not to solder or weld these in the field goes back to a basic construction principle: The world goes together with seams.

If you attempt to join a very thin piece of soft metal around two large plates and movement occurs on one of them (ie, someone sits, leans, or steps on one section near the edge), this can cause an aesthetic failure.  Despite our best efforts, even with a subtop, these two pieces can move, on a small scale, independently of one another.

Further, if this piece ever needs to be replaced for any reason, work would need to be done to reverse this weld to free the piece for replacement.

As a real-life example, I finished a job at a prominent golf club, headed home, and received an email early the next morning, which stated something to the effect of, “We enjoy the new tops and the installation looks great.  On another note, one of the light fixtures fell last night and destroyed a portion of the bar.  How quickly could you remake this section before our upcoming event?”

Knowing the melting point of zinc allows us to understand why there is not some alchemy that will allow tops to be welded or soldered on site over a flammable substrate made out of wood.

Seams should be left or simply caulked with silicone for basic bar movement and for the ease of future service, should you need it.