Granizo Mural - Cal State L.A.
Los Angeles, Los Angeles, California
Selective removal, restoration, and reinstallation of a 2,500 sq.ft. ceramic tile mural
A ceramic tile mural by William Granizo, comissioned for the 1984 Los Angeles Olympics at the site of the judo events, had begun to fail, with some tiles falling to the ground after deterioration of the mortar setting bed.
Wikipedia Reference: http://en.wikipedia.org/wiki/California_State_University,_Los_Angeles
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A ceramic tile mural created for the 1984 Los Angeles Olympics had started to fail, with several fallen tiles giving indication of the unstable setting bed substrate. The mural was designed and executed to depict all the events at the Summer Olympics. |
During the preremoval documentation, we were able to identify several tiles that were already cracked from previous movement in the setting bed and substrate. |
These cracks were present over wide areas of the mural, and presented a significant challenge in our efforts to salvage 100% of the original historic material. |
As with all our selective removal projects, common procedure involved the designation of individual units with a specific code to ensure reinstallation of the tiles in the same place and orientation as originally executed. |
Cracks in the tiles were sporadically located throughout the entire mural, and presented a challenge to our goal of a "zero tolerance loss policy" |
Sometimes there was evidence of moisture seeping from behind the tile body, here evidenced by the calcium deposits left at the hairline crack where the vapor was allowed to escape. |
We elected to keep the job site contained, in order to avoid moving all 2,500 tiles to a different location and to minimize potential damage from movement. Placing netting on the scaffolding also helped to control the silica-dust from removal and prep activities |
Since our test removal confirmed the unstable condition of the original thin set mortar, we elected to use light-impact demolition hammers with specially modified chisels. The chisels were custom-fabricated to present an 11 inch long chipping edge. Since this tool was being used on a 12 inch long tile format, it allowed the percussive force to be distributed along a broad aspect of the tile's edge, thus minimizing the chance of localized damage from overly agressive removal procedures. |
Gentle pressure with the chisel produced a result in which well over 99% of the tiles were removed without damage to the historic glazed surface |
Numerous areas of non-uniform adhesion patterns confirmed stories heard from those originally present about the informal, group effort to install the mural for the Olympics.. |
The back of this removed tile illustrates how a non-uniform and incomplete installation of thin-set adhesive can cause problems over time, especially in exterior environments. |
The quality of the original installation made it possible to sucessfully remove almost all of the tiles without damage. |
Some areas were well-adhered (given the ad-hoc nature of the original installation), but unfortunately approximately 50 tiles out of 2,500 were damaged during selective removal. Repair of these damaged tiles was an exercise in the reproduction of matching new surfaces that were compatible with the original substrate and adjacent undamaged glazed surfaces. |
A work area was established at the base of the wall to engage in the initial repair of each fractured or damaged tile. Note the felt-tipped numbers on the back of inventoried tiles to ensure that each tile is reinstalled in the original location and orientation. |
Repairs began with the assembly of the component pieces, and the application of adhesive tape to keep the tile together while it was turned over. |
After the tile was turned over on its face, the back could be strengthened using fiberglass mesh with epoxy adhesive to hold the component pieces together. |
Meanwhile at an adjacent work area, the undamaged tiles were carefully prepared for reinstallation by removing old grout and setting bed mortars. |
After readhesion of broken tile components, the units were turned again and the surface filled with a water-based epoxy repair mortar in preparation for application of final tinted coating at crack repairs. Note the finished crack repair in the rear and the unpainted units in the foreground. |
Our artisans used an acrylic-based coating formulated with UV-resistant components to give the optimum combination of performance and color-matching. Note the finished tile repair in the foreground. |
We used approximately 30 different custom color-matched formulations to bring back the original range of glaze colors in the repaired areas. |
Even minor damage spots such as this tiny glaze spall were repaired, because resistance to moisture intrusion is an important component of the restoration agenda. |
Another important step in the restoration procedure was the application of an anti-fracture membrane to the wall before the mural tiles were reinstalled. This layer between the tiles and the concrete wall provides an additional level of protection to the tiles from internal movement of the substrate. |
Reinstallation of the tiles could than proceed on a clockwork basis. Note the limited area of new thin set adhesive before the tiles, in order to minimize the chance of flash drying of setting bed before the tile could be placed. Flash drying was probably one of the major contributors to the unstable nature of the original installation. |
Reinstallation also allowed us to correct some of the original errors in the regularity of the tile grid. Careful use of shims made it possible to adjust the grid according to the dimensions of each individual tile. |
Adjustment of each tile could then be finalized before the thin set mortar began to harden. |
Final grouting of the joints and application of a water-repellent sealer to the joints completed the restoration. The next maintenance cycle for this extraordinary work should be signifcantly longer. |