Copper alloys are a term used to describe any artifact whose primary component is copper. The object may be alloyed with a number of other metals such as zinc, tin, arsenic and mercury. Without analytical studies, it is impossible to know the exact composition of a copper alloy. In the conservation laboratory, copper alloys are seen in many different forms and colors. Their corrosion is much more complicated than that of iron or lead, because they can be composed of so many different metals. Identification of the corrosion products is complicated as well. It is for this reason that minimal cleaning and investigation of copper alloys is undertaken, so that future analysis using scientific equipment can be completed if necessary.
This handle was sent to the conservation laboratory for routine cleaning. The surfaces were fairly clean and were covered in a well adhered obscuring corrosion.
As with many coppers, the corrosion was colored green, brown, red and black. The object was not complete and had suffered some damage during burial. Some of the corrosion was very dense in the middle area. The object was mechanically cleaned and the corrosion was carefully removed under the microscope. During cleaning, a design appeared in the surface of the copper alloy. As more corrosion was removed, it became apparent that a maker’s mark of some sort was impressed into the surface of the object. This mark revealed initials of “HL” in the surface as well as an emblem or symbol below. Because the object was damaged on the bottom half it is not clear whether the complete mark is revealed. As with so many objects, even though a mark like this is uncovered, it is still very difficult to identify what the mark means. But one thing is for sure, the mark is another clue to our past and is now available for further research and study.
Conservation often unmasks very valuable information hiding beneath a layer of corrosion. This specimen is the handle from a spigot and bears marks with the initial “HL” and some sort of creature, perhaps a dragon rampant. The object is the decorative handle for a stopcock like the one pictured below and of the type that would be used to tap a barrel of wine or other beverage.