2018-08-14 Conservation Treatment ProposalJensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
CONSERVATION TREATMENT PROPOSAL
Prepared for: John Mark Nielsen, Ph.D., R., Executive Director Emeritus, MUSEUM OF
DANISH AMERICA, 102 Courtvue Drive, Blair, NE 68008-1969;
Home Phone: 402.426.4825; Cell Phone: 402.427.4443,
amnielsen@abbnebraska.com,
Phil Green, Assistant City Administrator, City of Blair, 218 South 16th Street
Blair, NE 68008, Phone: (402) 426-6691, Fax: (402) 426-4195,
pcgreen@blairnebraska.orq
Pat Long, City of Blair, Superintendent of Cemetery and Parks,
patl@blairnebraska.org, Office 402-426-5244, Cell 402-533-8589'
Prepared by: Mayda Jensen, Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE
68144 402/691-010O.mayda@'ensenconservation.com
Date of Proposal: August 14, 2018
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, 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 3/4" h
City of Blair, NE Tower of the Four Winds Blair Parks & Recreation 1
Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
x 3/a" w x 3/16" d, today, the most common size of mosaic glass. Mosaic glass is difficult to out without shattering.
Portions of the composition requiring a great deal of glass cutting appear to be fabricated in stained glass
materials rather than mosaic tiles.
The entire mosaic composition was 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 sanded mortar was enhanced by
admixtures of acrylic adhesive. The perimeter has previously been sealed with flexible caulk 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 cut 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 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.
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 Blair Parks & Recreation 2
Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
CONDITION
Conditions of the Tower of the Four Winds have been assessed in 2015, 2016, and 2018. Loss of mosaic tiles is
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 mortar beds. In some cases, the water has introduced soil and
developed mold beneath the glass tessarae. Water has corroded steel and deposited stains on the glass mosaic,
particularly at the corners of the uppermost, vertical arm and the central circle. Flexible joint compounds have
shrunk and failed over time, allowing water penetration and migration inside the structure and behind the mosaic
facade.
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 have failed. Further repairs were
made to secure loose mosaic tesserae. Epoxy resin was selected. The resin repairs have 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.)
PROPOSAL
We propose conducting conservation treatment of the mosaic on site in Black Elk—Neihardt Park, in Blair,
Nebraska. Scaffolding will provide the best means of access to each square inch of the mosaic fagade. Treatment
will include:
a. surface cleaning of the mosaic to remove ferrous stains, dissolution of molds and mildew stains, removal
of failed flexible joint compound & backer rod residues, and accretions from epoxy repairs,
b. mechanical removal of the thin set mortar bed in areas where the glass is missing and/or separated,
City of Blair, NE Tower of the Four Winds Blair Parks & Recreation 3
Jensen Conservation Services, Inc. 13515 C Street, Omaha, NE 68144
C. setting new and/or existing glass tesserae into the existing pattern to compensate for loss in the intended
appearance in beds of acrylic modified, thin set mortar,
d. application of non -sanded grout,
e. replacement of flexible joint compound around the perimeter,
f. application of water repellent.
11-2016121IMM 701
Restoration of the Tower of the Four Winds is intended to renew the color fields of the large mosaic. Existing
original pieces of glass and commercially available new stock will allow for good color matches to compensate for
loss in the existing. Some stained glass may be needed to compensate for loss in original areas using stained
glass. Application of grout will alter the surface color to a brighter hue, since the existing is slightly darkened by
soil. The grout layer may be slightly irregular in depth because the existing surfaces are irregular.
The mosaic must be protected from water damage if the Tower of the Four Winds is to be preserved. Newly
adhered glass pieces will be 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 will to fill small cracks in original thin
set and to close gaps at the perimeters of the glass tesserae, thereby impeding the entry of water. Edges of the
mosaic will be sealed against water entry by the placement of flexible joint compounds in the gap between mosaic
and Cor -Ten structure. Finally, application of water repellent will enhance the rates of drainage and evaporation of
water from all the glass mosaic the surfaces. These proposed 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. Our
proposed restoration treatment will renew water repellent characteristics built into the composition originally. Once
restoration is complete, throughout ensuing years, 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.
QUOTATION
Conservation treatment to stabilize the mosaic face of the Tower of the Four Winds will be conducted on site, as
proposed above, for a sum of $ 187,450.00 for professional services, materials and hand tools, access equipment
(scaffolding), documentation, travel, and commercial insurance.
City of Blair, NE Tower of the Four Winds Blair Parks & Recreation 4
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