45th Annual Meeting – Objects Session, “The Case for Cold: Using dry ice blasting to remove lacquer coating from the King Jagiello monument in Central Park” by Matt Reiley

The subject of this talk was the treatment of the bronze statuary in Central Park, in specific the monument to King Jagiello (and despite the guided group-pronunciation lesson, no, I cannot say that properly – sorry Matt!). The overall project has a huge scope, as the bronzes were coated with Incralac in the late 80’s/early 90’s and have not been on a proper maintenance schedule, as is required for that type of treatment. The Incralac has cross-linked and begun to obscure the detail of the statues, and the old method of abrasive coating removal has not been good for the statues.


In order to complete the project in a timely fashion, dry ice blasting was determined to be the best course of action. The cleaning had to go hand in hand with addressing structural issues, as King Jagiello had already been noted to be unstable in 1984. The mounting issues were brought up again in 2009, and a process of removing and shoring up the base was completed in 2016. One of the most interesting parts of this, to me, was that a votive plaque of Saint Claire was found inside the sculpture – who knew that public monuments would have such things? The structural stability was improved, and the weepholes were cleaned and enlarged in order to address drainage issues and issues with active electrolytic corrosion cells.

Matt provided a number of technical details about the dry ice set-up, which I won’t reproduce here (but I suspect will be in the postprints), but I found especially useful, as I have been looking into dry ice cleaning for my own projects, and am interested in the baseline that others have established. He also provided a great overview of what you need to set up a dry ice system – the compressor, the dryer, the unit itself, and a hopper with dry ice.  The cleaning itself went exceptionally quickly, with complete coating removal in six days! Dry ice cleaning also helped the team achieve their campaign goals of sustainability and reduction of hazards. During treatment, noise level and air quality readings were taken to monitor the health and safety aspects of dry ice cleaning, which is an important factor that many seem to overlook. The treatment was completed with re-patination, a final steam clean to remove residue, and application of a hot wax coating.

I appreciated this talk for the great general overview of the ins and outs of a dry ice cleaning campaign, and I’ll be applying what I’ve learned next summer – and reaping another benefit that Matt pointed out, as the cool mist produced by cleaning definitely helps the conservator cool off on a hot summer day!