Why the stone gets cleaned before the glass

The 84.51° Building is a nine-storey commercial office building in the heart of downtown Cincinnati, built from precast stone and architectural glass.

What went wrong

Staining and weathering across both materials. Rain and snow over a long period had left the precast marked and the glass carrying mineral deposits and hard water spotting, the kind that builds up where water runs down the face of a building and dries there.

The order of operations is the point

On a facade where precast sits above glass, the sequence is not a matter of convenience. Minerals leach out of concrete, and every time it rains the runoff carries them down onto whatever is below. Restore the glass first and the next wash of the stone above puts the staining straight back onto it.

So the work went in one direction: clean the precast, seal it so it stops shedding minerals, and only then restore the glass underneath. Done that way, the glass is the last thing touched and nothing above it is still leaching onto it.

What was used

Stone Restore HD cleaned the staining off the precast.

Leach Stop went on next, sealing the concrete against mineral leaching, water penetration and erosion. This is the step that makes the order above worth anything: without it the stone keeps shedding and the glass below keeps staining.

Then the glass. Glass ReSurfacer Final Polish, worked with a Glass ReSurfacer Pad, took off the mineral deposits and hard water spotting and brought back the clarity.

Glass Defender finished it, as the coating that keeps new deposits from bonding to the surface and makes ordinary window cleaning effective again.

Getting to it

Access across the nine storeys was by swing stage.