dk nkf - Nordisk Konservatorforbund Danmark

Figure 10: 11-3/4” bolt removed from shaft flange.
the wrecking process, during which the Monitor
slammed stern-first into the seafloor. The majority
of the deformation is aft of the bolted flange and in
close proximity to the packing seal. In consequence,
a 6-inch x 8-inch section of the aft cast iron packing
sleeve fractured, revealing the aft packing ring and
some packing material (Figure 9). The packing
material is heavily impregnated with iron corrosion
products and concreted sediment.
Conservators have also utilized electrolytic
reduction on the packing seal. The assembly
currently rests in a 1.0% sodium hydroxide solution
in de-ionized water, pH 12. The artifact is wired to
a rectifier with stainless steel connections including
threaded rods and alligator clips. The rectifier is also
hooked to platinum-niobium wire anodes. An initial
potential of -0.978 V vs. SHE proved effective at
surface cleaning and reducing corrosion products.
The artifact remains in electrolytic reduction, and
chlorides continue to be released into the solution.
Conservators opted to partially disassemble the
shaft coupling. Prior to disassembly, conservators
documented and reproduced the wrought iron nuts
by molding them with an algae-based dental molding
material. This material proved highly effective
because it sets in a warm, wet environment, provides
detail, and cures quickly. Conservators then used a
commercial gypsum material to create casts of the
individual nuts. Modern pipe wrenches and a chain
wrench with rubber and canvas padding were used
to remove the eight wrought iron nuts that secure
the bolts to the flanged shaft assembly. The threads
were well preserved even though the surfaces of the
fasteners were highly corroded. Removal of a single
bolt revealed well preserved inner metal surfaces that
appeared unaffected by 138 years of immersion in
salt water (Figure 10). Conservators decided not to
separate the coupling because of the tight tolerances
134
between the two joined surfaces and the remaining
fasteners, and they also opted against removing the
cast iron packing gland because of the fragility of the
graphitized cast iron. Treatment of the packing seal is
now in its final stages of desalination before drying,
surface coating and re-assembly.
Conclusion
Mariners’ Museum conservators have expanded
their knowledge insight into the treatment of large
industrial artifacts by documenting and treating
the Worthington pumps, ventilation engine, and
packing seal assembly. This process continues to
provide insight into the materials and fabrication
techniques used by Ericsson and other shipbuilders
to expand the art of shipbuilding in the 19 th century
while laying the groundwork for the next stage in
the conservation of Monitor’s large mechanical
components, including the condenser and vibrating
side-lever steam engine.
The general treatment method for large marinerecovered
artifacts from Monitor includes many
steps. Metal artifacts are stored in corrosion
inhibiting solutions such as sodium hydroxide.
Each object is then examined, documented, and
investigated to better understand their composition
and condition. Active treatment begins with manual
and electrochemical removal of concretion and
corrosion, followed by disassembly of component
parts. Thorough desalination through chemical and
electrochemical means is followed by dehydration,
and application of protective coatings prior to reassembly
and museum display.
Experience in the treatment of these large marinerecovered
industrial artifacts has demonstrated
that a multitude of skills such as rigging, welding,
plumbing, fabricating, electrical work, engineering,
metallurgy, photography, and x-radiography are
necessary to support the conservation effort.
Substantial facilities are also required, including
large volumes of chemicals and de-ionized water,
rugged and flexible workspaces, cranes and rigging
equipment, storage and treatment tanks, and artifact
storage areas. The combination of these factors
and good treatment practices are necessary when
conserving large industrial artifacts.