2019-07-18 Conservation Treatment ReportJensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
CONSERVATION TREATMENT REPORT
Prepared for: Rodney A. Storm, City Administrator, City of Blair, 218 South 16th Street
Blair, NE 68008, Phone: (402) 426-6693, Cell (402)533-3535
rstorm@blairnebraska.=
Prepared by: Mayda Jensen, Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE
68144 402/691-0100 maga@jensenconservation.com
Date of Report: July 18, 2019
Artist: F W. Thomsen
Fabricators: Hanns and Monica Scharff
Title: Tower of the Four Winds
Date of Sculpture: 1987
Medium: Cor -Ten steel, pebble aggregate, glass mosaic tessare, stained glass tessare,
thin set mortar, grout, flexible joint compound
Location: Black Elk— Neihardt Park, Blair, NE
DESCRIPTION
The Tower of the Four Winds is an installation at the pinnacle of Black Elk—Neihardt Park in Blair, Nebraska. The
composition by Reverend F.W. "Bill" Thomson, a retired art professor of Dana College, was finished in 1987. The
Tower of the Four Winds measures 44' high with laterals stretching outward to span 26' feet in width. The base or
support of the composition is finished in exposed aggregate. The supporting exterior structure for the mosaic
portion is fabricated in Cor -Ten steel.
The decorative motif of the face of the mosaic is made from glass tesserae and stained glass pieces. Most
individual glass tesserae selected for this installation were fabricated as hot glass pressed in shallow molds with
tapered sides. Striations are visible on the faces of each of these glass tesserae. Standard measurements are 3/a" h
x 3/a" w x 3/16" d, today, the most common size of mosaic glass.
The entire mosaic composition was originally assembled in Los Angeles, section by section, with tesserae and cut
stained glass pieces adhered face down on paper.
The glass patterns are set on the face of the Tower in sanded mortar. The original sanded mortar bed was
enhanced by admixtures of acrylic adhesive. The perimeter had previously been sealed with flexible joint
City of Blair, NE
Tower of the Four Winds
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Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
compound applied over backer rod. The lower edge of the Cor -Ten structure is fitted with a drainage tray sloped to
transport rain to the back of the composition.
No expansion joints have been incorporated into the construction of the glass mosaic fagade.
The mosaic was fabricated in sections by adhering individual mosaic tesserae and out stained glass tiles face
down on supporting paper. Hanns and Monica Scharff from Los Angeles, CA are attributed with this phase of the
fabrication,
In the September/October 1987 Issue of the TILE INDUSTRY NEWS writer Drusilla McIntosh records stages of
support used beneath the glass. According to these documents', the layers supporting the mosaic include:
a)"Very heavy wire welded to the face of the tower"
b) A "scratch coat"
c) A "full mortar coat"
d) A "thinset and acrylic butter coat".
The mosaic was surface coated with 2 coats of Aqua Mix Penetrating Sealer to conclude the 1987 installation.
Photographs in the 1987 publication show the composition was created from the center outward, completing
installation of the entire form within the circle before installing patterns in the four arms.
CONDITION
Conditions of the Tower of the Four Winds have been assessed in 2015, 2016, and 2018. Loss of mosaic tiles
remains the most disconcerting of the conditions noted. Losses documented in 2018 outnumber losses
documented in 2015—for comparable locations within the mosaic—by nearly a factor of 2. For example, in the
areas adjacent to the large central figure, glass beneath the left sleeve had 109 losses in 2015, and 197 in 2018.
Under the right sleeve glass losses numbered 143 in 2015 and 292 in 2018. Glass losses observed above the
right sleeve in 2015 numbered 89 while the same area has loss of 161 in 2018.
Factors causing deterioration of the Tower of the Four Winds and losses of the glass mosaic pieces are numerous
but collectively are the product of weathering, specifically water damage. In this sculpture, water has eroded some
of the thin set mortar bed, running between the glass and adjacent materials of thin set and grout. Over time, the
water has loosened adhesion by diminishing the grout and mortar beds. In some cases, the water has introduced
soil and developed mold beneath the glass tessarae.
Flexible joint compounds had shrunk and failed over time, allowing water penetration and migration inside the
structure and behind the mosaic fagade. Also, stains on the surfaces of the glass appear to have originated from
the joint compound aging rather than from steel corrosion as previously thought.
1 Drusitta, McIntosh, 1987 TILE INDUSTRY NEWS VOL. 29, NO. 5, Tower of the Four Winds, September/October, p 7
City of Blair, NE Tower of the Four Winds 2
Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
Painted graffiti on the exposed pebble aggregate of the support was cleaned immediately by Parks. The paint
shadows are almost invisible now, having faded over time. Near the soil line the support exhibits 3 areas of loss. It
appears corroded steel re -bar inside the structure may have burst these small areas from the structure through the
process of oxide jacking.
Repairs made in the past include installation of flexible joint compound over backer rod along the perimeter
between the glass mosaic and the Cor -Ten structure. These joint compounds had failed. Further repairs were
made to secure loose mosaic tesserae. Epoxy resin was selected for those prior repairs. The resin repairs failed—
most likely from sun damage—turning the resin brown and causing the glass to once again be released. (We are
pleased to note the epoxy does not appear to have caused fracturing of adjacent glass, a circumstance we
observed in the other mosaic installations at street level, in 2015.)
CONSERVATION TREATMENT
Conservation treatment of the mosaic on site in Black Elk—Neihardt Park, in Blair, Nebraska was conducted as
proposed. Scaffolding was erected to provide the best means of access to each square inch of the mosaic
fagade. Treatment included the following stages of work:
Work began with efforts to dissolve and lift ferrous stains. It became apparent the stains were not ferrous in nature
and are, instead, permanent, insoluble stains from polyurethane caulk.
Using tungsten carbide burr bits measuring 1/2", 3/8", and 1/4", cavities in the historic mortar bed were enlarged.
The recesses were increased in size by the grinding action of the burr bits to allow accommodation of new thin -set
mortar.
Aged glass was retrieved from Blair Parks storage (courtesy of Pat Long) and from Carol Bagby (courtesy of John
Mark & Dawn Nielsen) who had collected and preserved the glass tessarae from the ground. Glass was soaked in
vinegar to dissolve and lift soil and other accretions. New mosaic tesserae were purchased to closely resemble the
color and textures of the original tesserae to compensate for the numbers of glass pieces lost during the years.
Following clues in the original glass patterns, new and historic glass tessarae were fitted into the mortar level and
secured with Mapei Mosaic & Glass Tile Mortar (polymer -enriched thin -set mortar). The mortar was mixed with
Mapei Polymer Additive.
The entire mosaic was grouted with Mapei Ultracolor FA Premium Grout in the color Bone.
Existing flexible joint compound and backer rod was removed from the perimeter of the composition and replaced
with new. We installed new backer rod and Vulkem flexible joint compound in Black.
Treatment was concluded with application of water repellent. We applied water -borne Miracle Sealants Company
Tile, Stone & Grout Sealer. We applied two layers by sponge. The product dried to a clear, undetectable finish.
City of Blair, NE Tower of the Four Winds 2
Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
RECOMMENDED MAINTENACE
The mosaic must be protected from water damage if the Tower of the Four Winds is to be preserved. Newly
adhered glass pieces are both mechanically locked and adhered into place through the fresh layer of acrylic
modified thin -set mortar. A fresh application of grout on the entire composition fills small voids in original thin -set
and closes gaps at the perimeters of the glass tesserae, thereby impeding the entry of water. Edges of the mosaic
were sealed against water entry by the replacement of flexible joint compounds in the gap between mosaic and
Cor -Ten structure. Finally, application of water repellent enhances the rates of drainage and evaporation of water
from all the glass mosaic the surfaces. These completed treatment steps will enhance levels of protection from
water entry.
The longevity of the restored Tower of the Four Winds will depend on maintenance of the composition. The Tower
will need on-going maintenance to refresh water repellency through renewed applications of water repellents, and
by replacing flexible joint compounds to keep water entry to a minimum. We recommend the water repellent be
renewed once by summer of 2020 and at intervals of three to five years thereafter. Maintenance of water repellent
coatings will enhance preservation of the grout layer from weathering.
City of Blair, NE Tower of the Four Winds
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