Silver Artifacts Conservation - April 17, 2014

April 17, 2014

Small trophy - full view - before

Tarnish is formed on the surface of silver when it is subject to high humidity, moisture or air pollution.  The silver combines with sulphur in the air or moisture to form silver sulfide (AgS) which is black in colour.  Removing this black material is usually done by polishing with a soft cloth.  Silver is easily scratched when polished.  In fact, no matter what you use to polish it there will be minute bits of silver worn away each time you polish often only visible by using a microscope.  Over time this will become a critical issue with silver laminates since the silver itself can be worn down to the base metal.  Not only do the scratches become unsightly but then you may have the brass colour showing through in some other parts of the artifact.  Often the base metal is a copper alloy such as brass but can be many other types of metal.  This photograph shows a trophy with a black sheen of tarnish, silver laminate on a copper alloy base, dust on the wooden base, and a strip of scotch tape.  The tape was loosely attached at the top back edge (reason unknown).

Small trophy - close-up - before

Conservation of silver involves several steps but the intent is to avoid  or at least minimize scratching the surface.  This is accomplished by using the softest materials readily available and a few simple techniques.  There are many commercial silver polishes available that are widely used and certainly perform the polishing quite readily.  However, what many conservators use is precipitated calcium carbonate which is a more pure form of chalk that is very gentle in the polishing process.  This material can be purchased relatively cheaply at most pharmacies.  You need very little every time perhaps only a tablespoon which you mix with distilled water to make a paste.  So the combination of the chalk with no impurities and a pure form of water will combine to make a polishing substance with very limited chance of scratching.

Small trophy - close-up - after

Small trophy - full view - after

Always use nitrile gloves to handle the silver to reduce contact with the oils, salts, and ammonia found on skin.  With every artifact the first step is to gently wipe the surface with a soft cloth to remove dust or any other grainy substances that may be present.  Moistening the cloth with distilled water may be done as well.  The polishing paste is then applied to the silver artifact with a soft cloth.  I apply it gently in a circular motion over the area to be polished.  I usually do this twice and find that in most cases there is still a bit more tarnish removed a second time. The polishing process is finished by a gentle wiping with a clean soft cloth. Again, the cloth can be moistened with distilled water.  

Lastly, the best way to store silver is wrapped in acid free paper within a tightly sealed polyethylene bag and at a relative humidity of 40% or less.  There are some conservation grade treatments that can be applied as a layer to the surface.  Also, there are anti-tarnish strips that can be stored in the bag with the artifact wrapped in the acid-free paper so it does not come in contact with the strips.

These photographs are of a trophy that was conserved in this manner.  This trophy dates from 1950 and was awarded during the Apple Blossom Festival in Kentville Nova Scotia Canada.

Prescott House Metal Objects - February 9, 2014

February 9, 2014

Prescott Hose - Archaeological dig, Fall 2013

In a previous post I showed how I re-assembed a glass bottle that was found in pieces at an archaeological dig at Prescott House, near Wolfville, Nova Scotia.  The first photograph here shows us working on the dig.  We were in a class at Acadia University learning about archaeology and history in the area.  The three of us on the left are working in an area that appeared to be part of the wall or foundation of a building.  The original house from the early 1800's can be seen in the background at top right.  Behind us is a road to a grounds keeper's shed.

I was given the opportunity to work on four metal objects that were found at the same location.  These are a belt buckle, ice creeper (not discussed here), button, and bone handled knife.  Each of these came to me in a plastic bag labelled with the location in which it was found and still immersed in the original soil in which it was found.  This is the best way of removing these from their original location because it allows me to assess the impact of separating them from their environment and perhaps, if budgeting permitted, to get the soil analyzed.  For precious objects this would be a necessary exercise to determine the best route of treatment.  The constituents of the soil would help make the decision on which chemicals to use for cleaning, preventive measures, and storage.  Since, in this case, we are dealing with a limited budget and non-precious objects (objects of lower value) this was not done.  However, it does not stop us from doing some basic conservation work on these interesting objects.

I have provided photographs of three of these showing before images in which you can see the results of cleaning.  There are several important lessons to be learned from this work.  All these had a very serious amount of corrosion products in an active state.  This was the result of many years where they were immersed in soil and sand subject to rain and snow with alternating freezing and thawing conditions typical of Nova Scotia.  All of which exert considerable stresses.

Bone-handled Knife

The bone handled knife was the best example of the stresses of moisture.  It was moist when it was removed from the soil and rapidly dried out.  One part of the bone handle came loose within minutes.  I suspect the moisture was holding it together.  This is repairable with the same adhesive used to reassemble the bottle in my previous post, Acryloid B72 restoration adhesive.  The blade of the knife was obviously broken at the end with a jagged edge.  There is an obvious pattern to the material showing as a layer over much of the blade.  I suspect that this was the sheath in which the blade was kept.  Very little cleaning was done on the blade to preserve this material for possible future testing.  All loose material was carefully brushed off  and the wax applied overall as a preventive measure.  The wax had the added benefit of sealing up many small fractures in the bone and making them much less visible

Buckle - front - before cleaning

Buckle - Front - Finished

The buckle shown here was a mass of corrosion, sand, soil, and plant root.  The layers of corrosion were heavy enough that it could not be completely cleaned off.  No parts of it was movable and the underlying metal is not visible at all.  Once again, any loose material was carefully removed and a layer of wax was applied.  This object reacts strongly to a magnet so is likely made of iron.

Button - Back - Finished

Button - Back - Cleaned

The button shown here proved to be one of the more interesting objects to work on because after cleaning and treatment a very clear pattern became visible on the back.  It is characteristic of fibres in cloth suggesting that this is either the remnants of the material the button was sewn onto or a piece of cloth it was laying next to while in the ground.  I did very little cleaning of this side - using only a very fine, soft brush to ensure that none of this material would be removed.  It is possible that in the future someone may wish to have the material removed and examined so preserving it was my priority.  The front had a pattern of two small circles and bumps but was very obscured due to corrosion.  The condition was such that we cannot identify a date or its usage.  Once again, a fine layer of museum grade wax was applied to seal it from further moisture damage.

In all cases these metal objects were accompanied with a two page laboratory record document that provides a detailed description, measurements, structure, possible history, manufacture, treatment applied, before and after photographs, storage and exhibit environmental control suggestions, and any other additional notes that were relevant.  These documents becomes part of the permanent record for the province of Nova Scotia and Prescott House the owners of these important objects.

Environmental Considerations For Mixed Collections of Historical Artifacts - 2014

January 21, 2014

The following discussion focuses on artifacts that are comprised of metals, glass, ceramics, papers, textiles, organics or in-organics all kept in the same space.  This document outlines the environmental considerations and conditions for their storage and display in general terms for community museums.  I have provided several references at the end for further detailed information specific to each type of material.

Many historical artifacts are made up of several different materials attached and combined in various ways and would benefit from careful environmental considerations.  Temperature and moisture fluctuations put undue pressure on their structure and in some extreme conditions can cause fractures.  Different metals expand and contract with temperature changes to different degrees.  This is also true for different woods which will have different moisture content as well.  Particularly fragile are some older papers, wood, and porous ceramics that are hygroscopic – meaning they can absorb and give off moisture.  Higher and lower moisture levels can be particularly damaging to their cell structure.  Condensation can appear in some metals at temperatures below 10 degrees Celsius.  This promotes corrosion and can negatively affect other materials when they are stored in close proximity.  Storage materials can also play a role in deterioration since we know that materials such as some plastics can give off gases and over a lengthier period of time when combined with moisture form a mild acid.  Glass is more stable as is acid free wrapping paper, storage boxes and envelopes.

Some general information for artifacts kept in a community museum environment follows where it is assumed that special air conditioning or lighting controls are not available for storage or display of these artifacts.  This is true for most community museums in Nova Scotia, Canada and in general terms, elsewhere.  However, Nova Scotia is subject to a climate similar to United Kingdom in that we have on average 85% relative humidity over the course of a typical year but colder weather (and snow!) in a slightly longer winter.  The freeze and thaw cycle over the winter months is particularly challenging when some museums shut off the heating systems or set the thermostat too low while the museum is closed.  This is also a concern for those who have historical artifacts in their homes and leave for a few months with the thermostat turned down and the humidifier turned off while vacationing where it is warmer. 

In all cases it is best to keep things in a steady state.  That is, to avoid rapid fluctuations in humidity, temperature, light levels and so on.  Even moderate fluctuations are to be avoided but are not as damaging.  Where possible, monitor the temperature and humidity as a minimum watching for wild changes over a short time.  There is relatively inexpensive equipment available to do this but it requires effort on someone’s part to check the results.  If you must turn the temperature down or bring the relative humidity up or down (for example, when doing building repairs) do it over a longer period of time and return it back to normal settings over a longer period of time.  This allows the artifacts to slowly adjust without cracking, getting condensation, and so on.

Dust levels and vibrations are also a consideration if work is being done nearby or in your building.  Recently we became concerned at a community museum when roadwork outside caused serious vibrations inside our building when heavy machinery was working on the street outside our door.  We packed some things away to ensure they did not suffer damage from dust, falling over or off shelves. 

Basic Environmental Factors and Recommended Levels
 

Relative humidity, the recommended acceptable level day and night throughout the year is 50 or 55% +/- 5% with the acceptable range of 45 to 60% for mixed collections.

Light exposure, recommended generally acceptable level is 100 lux (lumens per metre squared), high levels of lux exposure are not usually harmful to metals, glass or ceramics but are detrimental to coloured objects since it can result in fading of colours; levels above 300 lux can cause eye adaptation difficulties for visitors in some facilities.  Light exposure can be measured with a light metre as used by photographers.

UV radiation, the general recommended level of Ultra Violet exposure is 75µw/l (microwatts per lumen).  Extended exposure to sunlight is the most damaging although quartz halogen lamps are also a concern.  Do not hang or store any painted artifact in an area that is subject to direct sunlight.  UV can be measured with broadband UV sensors, for example, which is specialized equipment usually outside the budget of most community museums.  Just ensure that all painted or coloured artifacts (examples: samplers, paintings, prints, papers, most textiles) are kept out of direct sunlight.

Temperature, the general acceptable level in winter is 19 C +/- 1 C and 24 C +/- 1 C in summer with a minimum temperature of 10C at any time to avoid condensation particularly in metals.
  

References

This document is a general discussion and overview of environmental factors.  Please refer to the references below for more detailed information.

1) This is an excellent overview of general preservation guidelines and recommendations for mixed collections thanks to the Minnesota Historical Society:

http://www.mnhs.org/preserve/conservation/connectingmn/docs_pdfs/BasicPreservationConsiderations_002.pdf

2) Canadian Museum of Nature – Collection Conservation:

http://www.nature.ca/en/research-collections/our-collections/collection-conservation

3) Environmental Guidelines for Museums by the Canadian Conservation Institute:

http://www.cci-icc.gc.ca/caringfor-prendresoindes/articles/enviro/index-eng.aspx

Broken Bottle Reassembled - December 23, 2013

December 23, 2013

This year I participated in a class at Acadia University (Wolfville, NS CANADA) that did a fall archaeological dig at Prescott House.  I have been commissioned to do conservation work on some of the finds from this important dig and will document that effort over the next few blog entries.  The dig was on a very small area alongside a gravel driveway near the maintenance shed.  We know from historical records that there were several outbuildings and our archaeologist/instructor chose an easily accessible area that had some ceramics and metals poking through the ground.  One of the hopes was that an outbuilding wall would be found which could prompt additional archaeological digs.  We uncovered thousands of pieces of ceramics, bottle and window glass, hand made nails and various other metals, and bricks.  And we did find what appears to be a structure's wall which was a combination of brick and stone.

All 18 pieces of bottle found at Prescott House.

The first object I chose to work on was a bottle that was broken into 18 pieces of various sizes (see first photograph) yet enough of it was recovered to attempt to put it back together with conservation grade adhesive.  Why go to the bother of putting it back together?  It will allow us to take measurements, study its shape, and clues for its usage which will all help in identifying manufacturer, dating, and identifying contents.  In some cases bottles of the same contents underwent changes over time such as addition of markings.  This bottle has embossed lettering along both narrow sides which will become clearer when put together.

Tools used: scalpel, toothbrush, magnifying glass
Materials used: distilled water, B72 Restoration Adhesive

Careful washing and brushing of the pieces in distilled water will assist in reconstruction because it will remove loose dirt and other material buildup that would interfere with fitting the pieces together.  After careful drying it is best to do a "mock up" of putting the pieces together to determine the correct order.  I used very small pieces of scotch tape to hold the pieces together temporarily to see how they look when fitted together.  It is best to put some smaller pieces together first and then fit onto larger pieces.  Sometimes we actually draw out the shapes and number the actual pieces (using a non-permanent very fine marker) in the order in which they are to be reassembled.  This was not necessary in this instance since the 18 pieces were relatively easy to reassemble with only one exception.  I had a very small piece with no special markings that I was not able to fit anywhere.

I used a toothbrush to clean up the pieces, a scalpel to carefully remove excess adhesive and test connections, and a magnifying glass to verify connections.  By testing connections I mean that I used the scalpel to run along the fitted pieces to mark sure they were as close fitting as possible.  There were a few instances were I had to reset pieces so the scalpel was used to careful scrape away any excess adhesive.  One of the benefits of the B72 Restoration Adhesive is that it remains tacky for two minutes to allow for minor adjustment of fitting the pieces.  It is also reversible by applying heat greater than 100 degrees F.  It will not yellow and is relatively non-toxic although should not be used in a confined space and avoid skin contact.  It is widely used in conservation work for most materials except leather.

Of particular interest is the embossed lettering on the two narrow sides which have only one letter missing on one and a partial letter on the the other: one can be interpreted as "MOTHER GRAVES" and the other as "WORM EXTERMINATOR".  This is a known medicine from the 1880's to early 1920's manufactured by Northrup & Lymon in Toronto and used in the treatment of worms in humans, particularly children.  This series of  photographs show the reassembled bottle from all sides.

Reassembled bottle - front

Reassembled bottle - back

Embossed letters  "OTHER GRAVES"

Embossed  letters "ORM EXTERMINATOR"

Historical Note and Family Connection

Charles Prescott completed the building of Prescott House, a magnificent Georgian style house in 1815 and proceeded to make a serious contribution to horticulture and specifically the apple industry in the province.  He introduced over 100 varieties of apples among other endeavours.  But, for me, this has a family connection due to one variety he established called the Bourassa apple.  Unfortunately, we have not found any more information beyond the fact it was grown in Quebec from 1750 and up to 1880 when no more information is available.  We have not found the family connection yet either but, we will continue to search for it.  If anyone has information that would help us locate this apple variety (is it still grown?) or any of its history please leave a comment.

Locks of Hair - December 10, 2013

December 10, 2013

Locks of human hair have been kept as keepsakes for thousands of years.  This was usually practiced for several reasons: superstition, religious or sentimental.  Certainly it was much more common a hundred or more years ago but is virtually unknown in present times.  

Recently someone came into the museum to show me locks of hair that a female relative had put together of her children, herself, and husband as a keepsake dated from 1868. The locks were tied together with thread and sown along a sheet of paper to keep them all together.  The top of the paper is in two pieces that were sewn together when the locks of hair were attached to the paper as a group.  The bottom part of the paper is in two loose pieces.  The shapes suggest that they were torn apart as it was folded and unfolded over time.  Several types and colours of thread were used.  Near each cluster of hair was the person's first name in very fine ink writing.  It was likely done using a nib pen and ink well.  The handwriting was somewhat difficult to read due to the fading, creases, missing paper, and penmanship of the time.  The penmanship in my view is very beautiful but not something we are so familiar with in current times so a little more difficult to read.  However with the use of a magnifying glass and careful unfolding we were able to make out all the names.  Fortunately, the date 1868 is clearly shown which also coincided with the owner's family information on birth dates of the children whose hair was collected.  For example, one child was not included because they weren't born until after 1868 but all those born in that year and before were included so we could verify the date was correct.  It was also exciting to see that some of the writing on the back clearly was practice in forming some elaborate letters of the alphabet and words.  The author obviously was very concerned with penmanship which was an important part of education at the time.

Locks of hair - front

Locks of hair - back

Above are two photographs of the locks of hair as it was presented to me - front and back.  The hair appears to be in very good condition but I noticed that hair strands will come loose so any handling introduces a risk of loosing a few strands each time...not a good thing!  The paper is brittle and writing is faded.  Faded writing is common with the types of ink used in 1868 as is brittle paper from that time.  Having photographs will preserve the writing as of the date of the photograph.  One can try adjusting the contrast and brightness in the photographs with photo processing software to get the writing to be easier to read.

From a conservation point of view, here is what I recommend:

• try to avoid handling it as much as possible.  It is brittle and might break apart further and loose hair strands or bits of the paper.
• store it in a location where it will not be exposed to higher humidity or increased or constant exposure to light.  Both will hasten deterioration over time.  If storing in a mylar envelope keep it in a dark location when not being shown such as a drawer.
• store it in an acid free envelope if you wish to keep it without showing or handling OR use a mylar envelope which allows others to see it.
• if it is a larger piece, use an acid free backing board in the mylar envelope to eliminate the chance of it getting bent or folded .  This means only one side is visible (pick the best side!) but a photograph of the other side can be kept nearby but not in the envelope.
• mylar envelopes can be cut down to the size of each of the pieces so that it will not slide around.   Although this stores each of the pieces separately it means you don't need the backing board.   Otherwise you might have to attach it to the acid free backing board which is a challenge to avoid damage so don't recommend it.  Since this example comes in three pieces I suggest cutting the envelopes and backing paper down to size rather than trying to attach the pieces to the backing board.  Ordinary tape, perhaps see-through, on the outside can be used to close off any edges cut open.
• do not store it with any other objects such as other sheets of paper unless they are acid free materials.

It is possible to get mylar envelopes and acid free backing board from comic shops locally.  Contact the shop owner and ask them if they are willing to sell you a few of each.  I think getting two or three mylar envelopes and two or three acid free backing boards which will be not so much money is a good idea then you can cut them down in size or work with them to show off the hair locks in the best condition.  Whatever is left over can be used to store other important, older family documents.

Conservation Tips

Mylar envelopes are used to store papers and other flat objects because mylar is less likely to react to the materials stored in them.  Some plastics are not chemically inert.  That is, they may give off gases that mixed with moisture produce varying levels of acid or react negatively to some materials.  Mylar is certainly much more chemically stable and prevent odours and other gasses from penetrating to the interior.  Acid free paper for storage of most objects is useful again for the same reason that it will not give off harmful gases.  Avoid excessive handling of brittle objects of this type.  The less handling the better.

How To Identify A Powder Post Beetle Infestation - November 13, 2013

November 13, 2013

I spent an afternoon helping the Northville Farm Heritage Centre with identifying and isolating wooden artifacts infested with Powder Post Beetles.  I wrote about steps to take when dealing with an infestation and about infestation in general in the two previous posts so won't repeat that here.  This post has more pictures to help you search your own wooden artifacts.

Our objectives with the work at the farm centre was to:

• identify anything infected and remove it,
• place smaller artifacts in garbage bags to isolate them,
• place the smaller artifacts for a minimum of two weeks in a freezer,
• place larger artifacts that could safely be moved into a holding area,
• identify areas of significantly larger objects and structural infestation for future spraying.

We searched three buildings for the evidence of sawdust laying about or holes in the wooden artifacts.  Some of the holes look recent with lighter colours and sawdust others look older with darker colours and no sawdust.  These photographs show what we found for recent activity and what you can look for:

Barrel header with sawdust

Saw handle with holes and dust.

Butter churn heavily infested

With the older holes that usually have no sawdust treatment is still necessary since the larvae can survive for many years within the wood.  We bagged and froze the smaller artifacts as well and documented the larger ones for spraying in the spring.  Here is an example of what appears to be older non-active holes with no recent sawdust evident:

Brush with older holes.

Wheel, painted with older holes

We identified several areas in two of the buildings where spraying with Timbor should be done in the spring.  I wrote about spraying in a previous post and steps to be taken with infestation.  Timbor is safe to use and can be effective over a longer period of time to reduce the population of beetles.  Spraying is recommended in the spring around second or third week in June when the beetles are most active.  Fresh sawdust is the clear sign of beetle activity so cleaning up the sawdust shortly after spraying and monitoring for more will let you know if you need to re-spray. The farm centre has been doing this already for the last few years by spraying the structure of their buildings but now they can spray the larger, individual items we have seen that are infected.  Here are photographs of most of the artifacts we found with beetle infestation:

Most importantly, they must isolate all wooden artifacts as they come in. Smaller ones can be frozen for  two weeks; larger ones sprayed.  In both cases they should be isolated from the rest of their collection and only returned to the general collection when they have been treated.

One area had a large amount of sawdust on a barrel header on the main floor.  After removing it and searching for further evidence we came across a wooden butter churn that was heavily infested sitting on a shelf above.  The sawdust fell down between the shelf boards onto the barrel header below.

Conservation Tip:  It is critically important that all wooden artifacts brought in be inspected for infestation and if there is any evidence isolate them and treat them as soon as possible.  Isolation can be as simple as bagging or keeping them outside or in a building without exposed wood and cement floors.  Spraying is most effective when the beetles are active in the spring when they emerge from the wood for mating.  If you have had an infestation it is necessary to spray each spring over a period of years to reduce the population to a manageable number.  Regular inspection of your wood collection is necessary.  Remember that painting and varnish will not discourage them, they live in the wood and will bore their way to the surface.

Paper Artifacts Handling - General Information - November 2013

November 12, 2013

Paper Artifacts

As with all artifacts that come into the museum we examine each one carefully to determine the best way to proceed with cleaning, packaging, storage, and possible repair and display.  The following are some of the conditions paper artifacts are subject to which can be conserved usually under laboratory conditions:

1. stained by water, humidity or other liquids,
2. ripped, earmarked, 
3. missing pages, missing covers or in pieces, 
4. cracked or split spine, 
5. repaired with scotch tape, other tape or adhesives that is recent or has yellowed,
6. pest damage such as silverfish or book lice,
7. improperly mounted.

Each condition is carefully noted as a permanent record and appropriate action taken.  For community museums, only minimal treatment can be undertaken due to the costs involved.  That usually involves documenting, photographing, flattening minor rolls or curves, proper storing or packaging, some minor repairs with Japanese papers and paper adhesives if funding is available, and researching the history. 

For example, with earmarking such as corners folded or a part of a page folded back when stored or handled we resist the temptation to correct it by folding it back in place.  Attempting to correct it may cause further damage particularly if the paper is very fragile so is best left as is for now.  This type of condition can be corrected by engaging a paper conservator who will follow the correct procedures to do repairs such as applying humidification to a particular area or to the entire document to loosen the paper fibres, flattening the document, and drying it all under controlled conditions.  Paper artifacts that are moderately rolled or with moderately curved edges can be flattened by placing it between two larger pieces of thicker paper such as matting board and laying a large flat weight on top such as a piece of plywood of the appropriate size.  This does not always work if documents are severely distorted.  A paper conservator can help to determine if the humidification process mentioned above may be necessary.  Here is a photograph of a flattening in progress at the museum.

Large paper document being flattened.

It is possible to wash some paper under laboratory conditions to remove staining.  This is a labour intensive and often expensive process that is usually only done on very precious documents under highly controlled conditions.  Repairs can be done to replace pieces, fix cracks in spines, consolidate tears, loose pages or pieces.  Often Japanese papers of appropriate various thicknesses and colours are used for this purpose as is adhesives designed specifically for paper.  The papers are mostly used to stabilize the pages but in some cases can be colour matched to replace missing pieces.  Adhesives used in the past for attaching covers to books were sometimes a good source of food for pests; modern adhesives are designed to avoid this.  Modern adhesives are reversible, strong, and non-staining.  Examples are starch-based or methyl cellulose.  Stabilizing a loose or cracked spine on a book is a good preventive measure to avoid further tears or breaks.  A paper conservator can do this with near invisibility to the casual observer.

Precious paper artifacts should be packaged in acid free sleeves and labelled.  Another option is to use Mylar sleeves and acid free backing boards of the type that are used to store comic books.  These can often be obtained in local comic stores for a reasonable price.  Mylar is recommended due to its inert composition and acid free backing boards are important to reduce the chance of a paper artifact getting bent in storage or handling.  Mylar is also transparent which means it can be used to put a document in an exhibit and keep it protected.  Obviously this packaging is not the best option for all paper artifacts but should be done for those precious pieces.  The following photographs show two paper artifacts we recently packaged at the museum in acid free envelopes.  The accession number and archival number are both written on the outside of the envelope.  Cotton gloves are used for handling.

Cartoon booklet stored in acid free envelope.

1930 school book stored in acid free envelope.

References

CCI - Caring for paper artifacts  Canadian Conservation Institute - How to care for paper documents and newspaper clippings.
Asiarta Foundation - Works of art on paper conservation techniques - Paper conservation techniques
NEDCC - Repairing paper artifacts - NorthEast Document Conservation Center