Conservation-restoration of the Statue of Liberty

Many scientists, engineers, government organizations, and professional consultants evaluated and dealt with the various problems and tasks facing the restoration effort.

The centennial conservation-restoration project was formed by the National Park Service (NPS), the custodians of the statue since 1933, to investigate possible development alternatives.

The proposed measures included the instatement of systems for numbered ticketing and early warnings that would allow visitors to estimate any possible waiting times and to be conveniently advised if and when to visit or enter the statue.

In June 1981, the Committee was incorporated as a non-profit foundation licensed by the State of New York to raise funds for the restoration effort.

[2][4] The report, written with the assistance of a regional historical architect from the NPS, was an attempt to identify and address the apparent problems associated with the statue.

In the report, the consultants took note of what they saw to be the most serious problem affecting the statue: that two predominant sections, the torch-bearing arm and the rest platform at the head level, had corroded significantly.

Owing to this decision, an archive of two hundred large format photographs—both black and white, and multicolor—were developed for NPS and the Historic American Engineering Record (HAER).

According to The New York Times, the American Society of Civil Engineers (ASCE) would also be donating a set of three-dimensional computer drawings of the statue, rendered in the computer-aided design (CAD) program.

The 6,000 or so separate components of the scaffold, made of a high load capacity aluminum (alloy 6061 T6), were unloaded onto Liberty Island on January 23, 1984.

More easily an interior scaffolding was developed made of interlocking pipes held together with friction clamps and anchored to the central pylon of the statue for structural support.

The twenty UBS workers often resorted to assembling the interior scaffolding when the severe winds and dreadful winter weather conditions prevented them from continuing their work outside.

For the preparation of the wrought iron parts of the statue, an abrasive removal method also known as dry sandblasting was implemented in order to prevent against flash rusting.

The contractor firm responsible for much of the cleaning and painting of the Statue of Liberty, Ben Strauss Industries of New York, used over $90,000 worth of aluminum oxide supplied by Norton Corp. of Massachusetts to blast the corroded layer of iron from the rusting frame.

According to the evaluative research completed, the abrasive removal method (involving aluminum oxide) could damage the underlying layer of the copper substrate.

A commercial grade bicarbonate of soda, manufactured by Arm & Hammer was donated by the ton and applied as the cleaning agent that would be abrasive yet gentle on the copper sheathing.

The coating would have to be able to provide protection against corrosion in a marine environment and have to have a zero level VOC (volatile organic compound) emission rating.

In 1970, a patent was awarded to NASA for a zinc silicate primer coating called K-Zinc 531, the name owing to the ratio of silicon/potassium to water being 5:3:1.

An article in The New York Times of December 17, 1985 indicated that the most serious internal problem with the statue was the corrosion that had taken place in the iron armatures which provide the support to the copper sheathing.

[7] Eiffel knew that galvanic reaction would immediately pose a problem, owing to the dissimilarity of the metals used in the statue (copper and iron), which unless insulated would corrode rapidly.

The insulating layer had lost much of its functional isolating capacity due to exposure to interior condensation, leakage and possibly from other variable atmospheric effects of the marine environment.

Black tar streaks from these so-called "weep holes" were running down the exterior of the statue and had altered the patina of the external copper sheathing.

Replacement bars were annealed and sandblasted to remove iron filings and other contaminants that would or could eventually cause the stainless steel to rust, and then dipped in nitric acid for protection.

The "long term service behavior" of 316L stainless steel, according to a professor of metallurgy at Massachusetts Institute of Technology who had some involvement in the early stages of the restoration effort, was not known.

[17] The replacement bars of the iron grid system were insulated from the copper with a PTFE (Teflon) polymer resin tape produced by the DuPont company.

[20] The most significant problems were consequences of poor design and construction choices implemented initially, but Eiffel could not have directly been responsible for such glaring mistakes according to the (same) architect.

The latter option would have the intended effect of further reinforcing the repairs that had been made when the problem was initially noticed in 1932 by the War Department when it had jurisdiction over the statue.

A double level hydraulic glass elevator would be installed inside the base of the statue from which visitors would be able to access the crown by ascending a few steps.

Prior to the restoration, much of the internal structure of the statue was out of sight behind the mesh wire walls of the original helical stairs.

An article in The New York Times, published less than a month and a half from the centennial celebration, discussed the changes within the statue as being the most spectacular.

The journalist added: that "now that the walls have been removed, what is revealed is an interior that seems to combine the toughness of 19th century industrial construction and the grace of a cathedral.