Cultural values, made of plastic, begin to disintegrate
Museum keepers hurry to come up with how to preserve modern works of art and historical objects, falling apart into pieces
Dr. Odile Madden of the Getty Conservation Institute in Los Angeles holds a piece of degrading plastic used in studies of new storage methods
Keepers of the armor of Nile Armstrong at the National Aerospace Museum knew that this would happen. This miracle of engineering thought is made of 21 layers of various types of plastic - nylon , neoprene , mylar , polyethylene terephthalate , kaptone and Teflon .
The rubber layer of neoprene is the biggest problem. Although it is invisible and is under other layers, he, as the custodians assumed, should harden and become brittle with age, which is why the costume must acquire the hardness of the board. In January 200? the suit was removed from the store window and placed in a vault to stop degradation.
southern whales .
There are everyday objects describing human life: an electric can opener, a Pink Princess disk phone, plastic containers, 48 caps for coffee glasses (all different externally).
"Similar objects are in the collection of any museum, especially historical objects - they bring you back to the past. But the material side of keeping this point in time is very complex, "said Odile Madden, a plastic preservation specialist from the Getty Conservation Institute in Los Angeles.
To the left is the first completely artificial heart implanted in the human body in 1969. On the right is the sculpture by Dewayne Hanson "Woman at Meal" from 197? in which several types of plastic were used.
Dr. Madden pulls the cellulose acetate thread from the extruder.
Dr. Madden leads a small initiative group of scientists on contemporary art research (Modcon), which works to help the plastic to survive in centuries.
The first step for curators and other people will be to determine what plastic is.
"We use this word as one thing, although in reality there are hundreds of thousands of different things plastic," said Gregory Bailey, curator of the Smithsonian American Museum of Art.
Plastic is simply called something that is amenable to molding. Often plastic is a mixture of polymers - large molecules that look like long chains - and additives consisting of small molecules. The very first plastics were made from modified natural polymers like cellulose, but most of the modern plastic is based on synthetic polymers that last much longer.
Additives can be so-called. plasticizers, improving flexibility, or fillers, reinforcing the material.
"There are substances that impart opacity, dyes and sometimes even shine," Madden said. "As a result, you get a lot of opportunities for the composition of plastic."
The Getty Institute stands on a hill, so on a clear day you can see the Pacific Ocean from it. One day Anna Lagena, the curator, was digging in a bucket full of plastic objects, some of which were dull, some - broken into pieces.
The objects belonged to the basic collection used in studies of advanced plastic preservation methods. "This is the whole drama of the situation," she said.
She took out a toothbrush split in half. At the ends of the wreckage the plastic handle remained transparent, though yellowed. Near the break the brush was opaque, as if inside the handle blossomed a cloud of white flowers.
Madden placed the broken brush under the microscope.
"Our region began with rudimentary physical checks, such as a test with a hot needle," which they place on the surface to see if the plastic melts, she said. "If there is a smell, does it look like coniferous? Does he look like burnt hair? "
Toothbrush from the basic collection of the Institute
Today conservation specialists use advanced analytical technologies, such as microscopy and spectroscopy, to identify materials.
Under the microscope, white clouds on the brush handle turn into an intricate system of faults, from which other faults leave. Lagan and Madden instantly determined that this plastic was made from nitrocellulose , the old material, which is often used in the production of photo and film.
Keepers have seen damage of this kind many times. "No other plastic does not give such kinks in this form," Lagana said.
Scientific analysis is usually supported by archival research. "We spend a lot of time studying the history and production of these things," Madden said. - If we find a Lego cube made before 196? I will expect it to consist of acetylcellulose , and not from ABS ".
In the case of objects for which there is no information, it would be a good idea to start with spectroscopy, analyzing the interaction of molecules with light.
Madden brought the vase into a white and green stripes, and a small red appliance. The latter shines through infrared light, explains Michael Dutre, a scientist at ModCon.
Absorbing infrared light, the bonds between different atoms inside molecules will bend and stretch in a certain way, as distinctive as the movements of a certain dance. Studying these movements, recorded on the graph, scientists can determine the type of connections and try to make a conclusion about the molecules.
Lagan holds the vase motionless, while Madden touches it with the tip of the spectrometer. "I think it's polyethylene or polypropylene," says Lagana, and her guess is based on the tactile sensations of the vase and its smell.
Madden, on the right, with Melissa David, an intern, use infrared spectroscopy to penetrate the materials and better understand their composition
On the left Michael Dutre is experimenting with squeezing acetylcellulose. On the right are plastic blocks used to replace lost fragments, broken corners and missing parts using a 3D printer.
Dutra launched an analysis procedure on the computer, and a graph appeared on the screen. Lagan was right - the graph shows only the simplest connections between carbon atoms and between carbon and hydrogen.
"The lack of certain features suggests that this is polyethylene," Dutra said.
Madden takes out what used to be a powder box, but now her lid is very distorted, cracked and covered with a layer of white powder.
"Plastic lost a certain percentage of the mass," she said, due to the fact that the plasticizer came to the surface and took the form of a white powder. Without the plasticizer, the box became fragile, cringed, and finally cracked along the sides. Drying and percolation of additives are the two most common directions of plastic degradation.
In the Smithsonian Institution store curators discovered that on the left side of Armstrong's armor appeared a brown stain - this plasticizer came out of air ducts made from polyvinyl chloride .
This is because the molecules in the plastics are not aligned in the most efficient way, says Jane Lipson, a physical chemistry specialist from Dartmouth College.
They are similar to frozen disorganized liquids, in which there are many intervals of random size between molecules. Over time, large polymer molecules are slowly organized and packaged more efficiently, which is perceived by the unaided eye as compression.
Any additives consisting of small molecules percolate through the gaps until they reach the surface, turning into something like a sticky liquid or white powder. When heated, plastic degenerates faster, because molecules have more energy to move. "They, in fact, are finding a way to move into a more stable state," Lipson said.
Keepers often try to find the best conditions for supporting artifacts. "Most of the conservation process is to maintain a vault or storefront that helps slow the decay as far as possible," said Bailey of the Smithsonian Museum of American Art.
The package of measures may include ultraviolet filtration, which reduces accidental damage to the molecular bonds of plastic, which makes it difficult for a museum with a large number of windows. For the preservation of plastic works of art, it may also be necessary to maintain low temperature and constant humidity, which reduces the migration of the plasticizer, or to provide an oxygen-free atmosphere to prevent oxidation.
Collams with the team create a special showcase for Armstrong's spacesuit with carefully selected conditions: 17 ºC, 30% humidity, and pollutant-removing filters. The keepers hope that the showcase will be finished by the next year, when the moon will be 50 years old.
Even such a harmless action as cleaning an object for an exhibition can be a difficult process. For example, the task of cleaning the plasticizer from the surface seems to be quite simple, but cleaning prompts the release of even more plasticizer, which, in principle, accelerates degradation.
"The plasticizer is simply trying to find an equilibrium between the outer and inner sides of the plastic," Shoki said. "But as soon as the balance is broken, a catastrophe can occur."
When observed through a polarizing filter on a plastic plate, traces of damage to the material, diverging from the center, can be seen, which makes it possible to understand exactly how this composition degraded with time.
Conventional dusting can scratch the soft surface of the plastic, ruining the clean and shiny polish. As an alternative, Shoki for the first time applied the technology by which tiny microcrystals of dry ice, snow from carbon dioxide, are directed in the form of jets on the plastic surface, collecting dust and other contaminants from it.
Despite its notoriety as the main polluter of the planet, plastic has a lot of things that are important for the story. Even if we give up plastic, Shoki said, "I believe that there is a need to preserve this memory in human culture."
He remembered the story of a tortoise shell and his plastic twin, acetylcellulose. "We managed to almost exterminate a certain kind of turtles," Shoki said, "but then we were able to move from natural material to an alternative."
"The fact that we use them instead of traditional materials has its own reasons," said Janet Garcia, an expert in polymer chemistry from IBM. For the most part, this is because the plastic is cheap and versatile, light and durable.
Plastic bottles help to transport water to remote places, light composite materials help to save energy in cars and airplanes, disposable syringes and blood bags help prolong life. Prostheses replace the refractory parts of the body.
"Partly thanks to plastic, we can experience our bodies," Madden says. Not to mention sending people into space.
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