Flag during conservation

Flag during conservation

Wednesday, March 18, 2015

An unusual Civil War Battle Record

This past autumn, an unusual artifact was delivered to the studio. It is simple in construction, basically a long width of cotton fabric, and on it painted a list of words in basic black paint. So far nothing so amazing, until the words that were so carefully and beautifully written in very different fonts were read.

The banner before treatment.

Each line of text was a separate battle that the 136th New York Volunteer Regiment had been engaged in during the Civil War. In essence, this width of simple cotton fabric was the regiment's war record. Such "battle honors" are more standardly recorded and seen on both National and Regimental flags of a regiment, often recorded on the stripes (see image below). Whereas this type of simple and utilitarian artifact was quite different. Why was such a piece created?

Detail of another NY Regimental Flag. Here the battle honors are recorded onto the stripes, this was a common practice and is the way battle honors are typically recorded.

The regiment was mustered into service in September of 1862 and composed of men from Allegheny, Wyoming and Livingston counties. The banner was clearly locally made. The banner is signed, "Made by the Nunda Sign Co." (Nunda is a town in Livingston County). Interestingly, the war record as written in the memoirs below (see more at NYS Military Museum's webpage), states the battles to be far more than those recorded on the banner, and the battles on the banner do not quite match those in the record, why would that be? (Also of note is that "Kulp's Farm is called "Kolb's Farm in Confederate records).

…"fought its first battle at Chancellorsville, losing a few men killed, wounded and missing; and was heavily engaged at Gettysburg on the first two days of the battle, losing 109 in killed, wounded and missing. In Sept., 1863, it was ordered to Tennessee with the nth and 12th corps and was engaged the following month (November 1863) at the midnight battle of Wauhatchie, Tenn., losing 6 killed and wounded. It was active at Missionary ridge in the Chattanooga-Ringgold campaign, losing 11 killed and wounded. When the 20th corps was formed in April, 1864, it was attached to the 3d brigade, 3d (Butterfield's) division of that corps, moving on the Atlanta campaign early in May (1864). It was active at the battles of Rocky Face ridge, Resaca, Cassville, Dallas, Kennesaw mountain and in the siege of Atlanta. Its heaviest loss was incurred at Resaca, where the casualties amounted to 13 killed, 68 wounded and 1 missing. After the fall of Atlanta it remained there until November (1864), when it marched with Sherman to the sea, engaged in the siege of Savannah, and closed its active service with the campaign through the Carolinas, in which it was engaged at Fayetteville, Averasboro, Bentonville, Raleigh and Bennett's house, losing 45 in killed and wounded in the battles of Averasboro and Bentonville. After the close of the war (April 9, 1865) it marched with its corps to Washington, where it took part in the grand review, and was mustered out on June 13, 1865, under command of Col. Wood, who was later promoted to bvt. brigadier-general and major-general. The regiment lost by death during service, 2 officers and 74 men, killed and mortally wounded; 1 officer and 91 men, died of disease and other causes, a total deaths of 168".

The banner may make mention of just the campaigns (Atlanta for example) rather than naming the individual battles (Resaca for example was a battle within the Atlanta campaign that lasted from May 13-16 of 1864). For a detailed timeline of 1864 (and any other year) go to historyorb.com.

The banner was in brittle condition when it arrived to us, it was mostly intact but very dirty, had several tears, and had a very sticky tape applied to the reverse side. Therefore, the treatment of the banner involved several things: cleaning, repairing the tears, removing the tape (see image directly below) that had been applied to the reverse side hems at both the top and bottom, and mounting the banner along with it's original rod and rings. As mentioned above, the banner was quite dirty when it arrived (see second image below). And amazingly, the banner was still paired with its original rod and brass rings (see third image below).


Detail of the reverse top of the banner showing the tenacious tape that had been secured to the top and bottom hems.
Dirt removed from the banner following the wet cleaning 

Detail of the original rod and one of the brass rings (safety pin not original).

With some some simple searching, it was found that after the war, the Regiment dutifully returned their Regimental, National, and guidon flags back to New York State. The assumption could be made that this banner was created out of a local desire to commemorate the efforts of this regiment in the absence of the flags.

The banner, after treatment, mounted and hung. 

Surprisingly, the exact date this banner was made is not readily known. Perhaps it was made soon after the 136th was mustered out of service, or maybe years later as a commemorative item for an anniversary of the 136th returning home? Perhaps at the close of the war? 

To see more about this banner, visit the website for the Livingston County Historical Society, where the banner is on display as part of their Civil War exhibit.

Thursday, March 5, 2015

Women want to vote! Conservation of artifacts from the Women's Suffrage Movement.

The most important way I can think of to celebrate International Women's Day on Sunday, March 8th is to honor the women who fought tirelessly to secure the right to vote. The Women's Suffrage Movement is one of the quintessential time periods in women's history; and to imagine that the 19th amendment is just 95 years old this year is amazing. How far we have come, and how far we need to go.

The Finger Lakes region of Central New York was an active place in the nineteenth century. So many of us are familiar with the stories of Susan B. Anthony and Elizabeth Cady Stanton and the town of Seneca Falls, New York; birthplace of the Women's Suffrage movement. But less than 25 miles away there was a hot bed of activity in Sherwood, New York, which then, like now, is just a dot on the map with no traffic light, only cross roads.


In 1837 Slocum Howland (1794-1881), a Quaker, abolitionist, prohibitionist and suffragist, built the Howland Stone Store Museum in Sherwood, a crossroads between Cayuga and Owasco Lakes to the west and east and the cities of Auburn and Ithaca to the north and south. Cayuga Lake gave it easy access to the Erie Canal.

According to the museum, "The Howland family, particularly Emily (1827-1929) and her niece, Isabel (1859-1942) were prominent in important reform movements throughout the nineteenth and early twentieth century, particularly in the abolition of slavery, education, and women's suffrage. A prized Museum possession is an Underground Railroad pass brought by two slaves who escaped from Maryland and came to Slocum Howland seeking freedom in 1840 (image is below. the display mount is two-sided). Emily Howland first taught in schools for free blacks in Washington, D.C. in 1857. In addition to building a school in Sherwood, she founded and financially supported fifty schools for emancipated slaves, teaching in several of them."


Both Emily and her niece, Isabel were active in the local, state and national women's suffrage movements. The sign below, is from the collection at the Museum and is a clear message. The sign was treated here at SAC last year. The tears in the canvas, as well as the cracking paint, were all quite pronounced. The top image is before the treatment, while the bottom image was taken after treatment.



Patricia White, director of the Museum and a descendant of the Howland family said Emily Howland first met Susan B. Anthony in 1851, and maintained a close friendship with the woman throughout her life. Although her sympathies always remained with the fight for equality (and her unending desire for education for anyone, regardless of their color), Howland started to get more heavily involved in the national movement for suffrage in 1891.


That year, Howland started the Cayuga County Political Equality Club (image above with the "5315" sign in the foreground), and organization. White said the politically active group, housed on Auburn's Exchange Street, was comprised of both men and women who carried around and collected petitions (which, I would imagine from the image above, were signed by 5,315 women!).


And although women didn't earn their final goal until 1920, White said Howland and her colleagues
won small victories along with way — such as the right for men and women to share joint legal
custody of their children, and finally changing the law to allow women to inherit property from their
husbands.

But eventually, the petitions, speeches and marches paid off. And at age 92, Emily Howland
headed to the polls and, for the first time, legally cast her vote.

Recently, our SAC studio manager's 9 year-old daughter had the opportunity to play with her third grade basketball team on the "big court" at a local college just prior to the women's basketball team taking the floor for a game against a rival university. They quickly realized there was a big event also taking place on the campus, a "Woman's Expo". As they neared the door, the 9 year-old looked up at her mother and asked, "what is a woman's expo anyway?". The reply from mom was that she hoped it was about leadership and decision making and equality and the amazing things women are capable of, and do, each and every day!

Sadly, it was focused on shopping and make-up. UGH!


Thursday, January 29, 2015

Creepy, crawly, and hidden in your collection?

Recently SAC posted a couple of images of a moccasin that got some attention. Mainly because many were interested in what was found in the "out of sight" parts of this artifact. The moccasin (pictured below) was purchased ca. 1923 and was believed to be made by the Onondaga for trade purposes. Is is one of a pair that are made of semi-tanned leather and elaborately embellished with glass beads.

The beaded vamp of the moccasin before treatment.



The underside of the vamp before treatment. Here you can see that the wool layer (which should be between the leather and the vamp) is missing. The small dark regions are the moth casings. 

Traditionally, when a moccasin like this was being made, the glass beads were sewn to sandwiched pieces of paper and leather that would make up the decorative pieces of the vamp and cuff. These parts of a moccasin were typically embellished separately before being attached to the moccasin. To cover the backside of the stitching of the beads, a wool layer was commonly used to line these sections. In the case of this moccasin, the wool layer is missing, because it had been breakfast, lunch, and dinner for some hungry webbing clothes moths. Delicious!

These little, but incredibly voracious bugs have long departed from this moccasin, leaving behind the remnants of their stay: the casings in which they morphed from larvae to moth. Like most infestations, there is no simple way to know when this infestation occurred.  What is important now is that the infestation is inactive. However, as evidenced from the amount of casings found, these moths certainly were very happy when they were here.

The lifecycle of a moth.

You may wonder what it was about this location (i.e. under the vamp) that made the moths so content to stay. Webbing clothes moths (and other pests) prefer to be left alone and undisturbed. They also really like dark locations, and if the location is slightly damp and warm, it is even that much better! The fascinating part here is that webbing cloths moths also like to graze the surface of semi-tanned leather, but in this case there is no evidence of this type of damage. Therefore they were content with the wool alone.

From the exterior of this particular pair of moccasins, you would not be able to detect what was within the layers below the surface. However, being aware of the placement of the wool layer both under the vamp and cuff, and knowing that it provided a paradise location for pests, helps to understand safe storage/collection management for this particular artifact in the future.

So how do you prevent this type of damage from occurring with your artifacts? You need to practice IPM, otherwise known as Integrated Pest Management. The basic philosophy of IPM is to make your environment as inhospitable to pests as possible and to avoid the use of chemicals (read our recent post on moth balls). An inhospitable environment can be accomplished with these simple steps:

1. Inspect and "disturb" your artifacts regularly, particularly those that might be enjoyed most by pests.
2. Treat your vacuum as your best friend and use it often.
3. A cold and dry location is the best location to store your artifacts.

It is always best to avoid pest problems rather than reacting to infestation.  Remember the motto of IPM:       
"Prevention is better than cure"

If you want to know more about museum pest management check out this website: http://museumpests.net

And if you cannot help but find humor in museum pest management, you must see Historic Cherry Hill's youtube video to better understand the insect's point of view!

Friday, January 23, 2015

One suggestion to lower the handling of artifacts

Safe and proper handling of artifacts is a major factor in protecting any collection. An important part of safe handling is knowing what you are handling. This means being able to fully understand how the artifact is packaged.

Acid-free tissue paper is a basic storage supply used for interleaving, padding, covering, and wrapping. It comes in sheets or rolls. Tissue has been in active use in museums for decades and we have talked about its substitution here in our blog about acid free materials.

Tissue is used in abundance. When I visit institutions, it is most common to find artifacts wrapped in tissue (and occasionally wrapped in Tyvek or other wrapping material). Often when an artifact is delivered to me, or if I am examining it at an institution it is presented just like a gift wrapped package, with the folded ends of the tissue all tucked under the artifact.

A print wrapped in protective glassine, where the upper
and lower edges are folded under.

Sometimes these packages are then placed into a box surrounded with wads of tissue, making it a treasure hunt of determining which wad is the artifact, and which is just paper. This hunting game is not necessary, nor is it in the best interest of the artifact.

Hats or any type of head-gear seem to be the type of artifact that is the most probable to be stored this way. Especially unfortunate as that hats and head coverings also tend to be embellished with fragile and delicate attachments, like feathers, which are particularly vulnerable to damage when wrapped this way.

As a conservator, I find this type of gift wrapping troublesome. This is because it causes the artifact to be unnecessarily and overly handled. Also, if you do not know a collection, you do not know what is fragile or not. When all is hidden, it necessitates a hunt in the tissue to even find what you are dealing with.

I understand that this type of packing was done with the utmost interest in protecting the collection and certainly that can never be faulted. In addition, there are many (now outdated) manuscripts that had promoted this type of care. But the museum field has now revised their thinking and certainly there are still times when paper is necessary because it is the best choice for an updated method of protection, interleaving, or just general storing.

What I am proposing is that when tissue is necessary to protect collections, that the artifact is easily unwrapped and will require no lifting or touching of the actual artifact. It would look like this:

A small purse embellished with metallic threads is placed on tissue that rests
on a handling tray fitted with twill tape.
All of the layers are folded to the top or upper surface of the artifact.
Wrapped layers are all accessable without need to lift or handle the artifact.

While unwrapping the above artifact, it did not need to be lifted or handled to be seen. The paper was folded and positioned in such a way that it was both protective of the artifact, while also being accessible.

Another solution is not to wrap at all. Here is a pair of epaulettes and their original box, both secured on Ethafoam supports and protected within an archival box.


Wednesday, December 31, 2014

What is your base knowledge about Rare Earth or Neodymium magnets?

Sometimes we just need to begin with the basics.


There has been lots of talk recently amongst conservators about Rare Earth Magnets, specifically rare earth magnets composed of the element Neodymium. These neodymium magnets have gained a foothold as the "go-to" magnet for mounting artifacts for exhibits and display. That is not say that this particular type is the only suitable rare earth for conservators to use, just that our literature indicates it is the most popular choice. Besides Neodymium, the other rare earth magnet for conservators is a Samarium Cobalt.

Rare Earth?  Neodymium? Samarium Cobalt? What do these terms really mean, and is there a big difference from one magnet to another?

To begin with, rare earths are not really rare, nor are they precious. They are actually as common in the earth as lead or tin. What makes them "rare" is that the elements that make up the rare earths are hard to come by, meaning mining for these elements is no easy task, and when they are found, the process to isolate them from the surrounding materials is quite difficult.


On the periodic table they are the upper row of elements that sit below the table (the plum color). (The lower fuscia colored row are the radioactive elements). They are part of the Lanthanide group of elements. Of the four permanent magnets, all developed in the twentieth century, two are made of elements from the Lanthanides; Samarium and Neodymium.

Conservators may be partial to Neodymium magnets for several reasons. They are cheaper than Samarium magnets, but more importantly, Neodymium magnets are strong, compact, permanent magnets, and they have the highest magnetic field strength as well as a higher coercivity (which makes them magnetically stable). The downside is that they have a lower Curie temperature (tolerance to heat  exposure) and are more vulnerable to oxidation than samarium-cobalt magnets. Samarium magnets, are more prone to corrosion and are far more brittle.

So it is an easy choice for many conservators, the neodymium magnet is the logical choice. The drawbacks (i.e your neodymium magnet being demagnetized because it is exposed to high heat) can easily be avoided. Simply do not use hot-melt glue with your neodymium magnet. Other options are available, like countersunk magnets to accommodate a screw for instance.

Hot melt glue and neodymium magnets just don't go together. The temperature of the glue
(even the kind marked "low temp") is just too high and will render your magnet useless.
Neodymium magnets begin to lose strength if heated above their maximum operating temperature,
which is 176°F (80°C) for standard N grades. They will completely lose their magnetization if
heated above their Curie temperature, which is 590°F (310°C) for standard N grades.

So now that we have established why neodymium is the logical choice, lets talk about the variety of neodymium magnets that are available. Not only do they come in a variety of sizes and shapes, but they are available in many strengths as well. Essentially that means these magnets are labeled in a way that tells you how strongly they "stick" to a ferromagnetic surface, which is perhaps the most useful information for conservators as we are often looking for a delicate balance of supporting an artifact, but being careful not to cause any harm to the artifact.

A very small sample of the sizes and shapes of Neodymium magnets available.

Neodymium magnets are marked N35, N38, N42, N52…but what does that mean? According to our favorite magnet distributor, K & J Magnetics, "Neodymium magnets are all graded by the material they are made of. As a very general rule, the higher the grade (the number following the 'N'), the stronger the magnet. The highest grade of neodymium magnet currently available is N52. Any letter following the grade refers to the temperature rating of the magnet. If there are no letters following the grade, then the magnet is standard temperature neodymium".

One of the smallest Rare Earth Neodymium magnets available.   This N52 measures 1/16" in diameter and only 1/32" thick!

The magnet above is an incredibly small magnet, yet as a N52 magnet it's pull force is quite strong.  Finding a balance between size, shape, pull force, and other factors to accomplish a mount is challenging. One would wonder if you could simply weigh your artifact and then figure out how many magnets would hold it up, and maybe add a few extra as a safety feature. But as we all know, nothing is ever that simple. For Conservators it is not just about holding the weight of the object, but how intact is the object, and what is it's ability to hold it's own weight. Sadly, there is no way to measure that. So we build in safety factors, like an angled display board, or a display fabric to provide some built-in friction for a textile.

So often I hear, "oh, magnets?! I know all about those" only to discover that the real magnet knowledge of the speaker is limited, it is only the term "magnet" that is familiar. Understanding that magnets are part of a broad and diverse world is the first step in using them properly.  Being familiar with magnets and their properties is the first part of creating a successful mounting system. In future blog entries we will discuss the other parts of a magnet system: The gap (or space in between the magnet and the ferromagnetic material) and the ferromagnetic material (what the magnet is attracted to).  Once these parts are understood, their cooperation together and the ways in which they can be altered, can be utilized to create inventive and successful systems.

Tuesday, December 23, 2014

Shipping or traveling by air with Rare Earth Magnets

Recently, when I purchased some magnets, I noticed the box that they came in was labeled: "Not packed for shipment by air." What does this mean?



The box was small, only holding a few rare earth magnets in a zip-lock bag and the entire box was filled with crushed paper. I began to think, "what more was needed to ship this package by air"? Is there a concern with the pressure in the baggage compartment of the plane? Could the few magnets in the box effect flight instruments? Neither seemed possible or a significant issue. 

So, I looked into it further. First, I found that magnetized material is NOT regulated as a hazardous material when transported via ground/surface transportation. However, the U.S. Department of Transportation has determined that rare earth magnets pose a safety risk when shipped by air unless they are specially packaged. Many suppliers do not provide such specialized packaging, and therefore do not transport via air. Perhaps they do not want to take the time to concern themselves with the added time to determine this. We know of one trusted supplier who does, to see how they ship their magnets via air, see the link below for K & J Magnetics.

It is important to realize that when groups of magnets are in close proximity to one another, their field forces unify and thus increase. Therefore if a large or moderate quantity of magnets are shipped together, shielding of some sort could be necessary.


Is it safe to take magnets on airplanes? Yes and no. Magnets can affect the navigational equipment on an aircraft. However, most single small magnets are not capable of significantly affecting these instruments from a moderate distance. But to determine exactly how strong a magnet(s) would have to be to affect the instruments, and how close they would need to be to do so, the US Department of Transportation and the International Air Transport Association have set precise guidelines for the transport of magnets by air. If the magnets you are transporting exceed certain thresholds, they will be considered Class 9 Hazardous Materials and should only be placed on an aircraft by trained and certified personnel. 

So, what are the rules?

According to K & J Magnetics,
"There are two important measurements of a package containing magnets. Rule #1: If the field strength is 2 milligauss (0.002 gauss) or more at a distance of 7 feet from the package, the IATA (International Air Transport Association) says the package needs to be labeled as Magnetic (see below). This is especially applicable for international shipments.


This label would be placed on a package containing magnets being shipped via air.

Magnets are often shipped in a steel-lined box to remain below this limit.

If there is any chance that the arrangement of magnets could change, or any package shielding could be damaged so that a measurement exceeds this value, it falls under the Dangerous Goods category and should be labeled as Magnetic.

Rule #2: For any package shipped by air, whether it is labeled magnetic or not, the field strength must be 5.25 milligauss or less at a distance of 15 feet from the surface of the package (FAA Title 49, Part 173.21 Forbidden materials and packages). If the package measures above this value, don't ship it by air.

Why are these rules so important? The magnetic compass. Despite all the fancy GPS navigation systems, the basic compass is still an important part of aircraft navigation. If a cargo of magnets alters the compass readings, accurate navigation might be compromised.

Remember, your magnets are competing with the magnetic field of the Earth, whose strength is only about 0.5 gauss on average."

So the short answer is that a magnetized material is considered a hazardous material and is regulated as a hazardous class 9 material when it is offered for transportation by air and when it has a magnetic field strength that is capable of causing the deviation of aircraft instruments. 

This image from K&J Magnetics shows a packing
method to keep magnets as far from the box walls as possible.

So how do you put this into practice? Well one way is with the use of a compass. That's right that ancient tool that was invented when the mysteries of magnets and Lodestone were first put to use. With your compass you can also measure the field distance of the magnets inside a box. (The first link below also includes a great youtube video showing this!) Remember, the farther away from a magnet you are the more the field force drops.

Read more of K & J Magnetic's article at: https://www.kjmagnetics.com/blog.asp?p=shipping
some other sites to visit:
http://www.rare-earth-magnets.com/t-safetyinformation.aspx
http://www.mceproducts.com/knowledge-base/article/article-dtl.asp?id=10

Friday, December 12, 2014

Ferrous Attractions - What was experimented with?

In the last few weeks some questions have come up about testing magnetic systems and how to determine the proper system for mounting an artifact. While more and more conservators are turning to magnets (YAY!!!!) as a solution for mounting, there is still some information out there that may be confusing, here I hope to clear that up!

Below is a recap of the hands-on session conducted by Spicer Art Conservation at AIC's 2013 annual meeting. This hands-on session was an opportunity for conservators to test various types of magnets,  ferromagnetic materials (sheet metal, metal strips, embedded washers, etc) and gap materials (the artifact, mylar, display fabric, or other interleaving materials).  

About 80 participants were present for the early morning hands-on session. For those who were unable to attend AIC's 2013 annual meeting, or were at the meeting but were at other specially groups, here is just a quick summary of the session and the important outcomes observed by the various groups. Read the earlier blog post for a full description and details of the materials we used and how the tests were performed. The goal of the session was to become acquainted with the diverse variables of a magnet system. (1. The strength of the magnets; 2. The ferromagnetic materials; 3. The gap or space between.)

Conservators busy experimenting with magnets.

Small groups of 4 – 5 participants were created. Each group had a "jig" (a stand and a combination of a magnet system, and pre-measured weights to test the system with). Any combination of the system could be used. Fabrics, paper, Mylar, etc, were all placed between to act as a gap. Performing each trial 3 times was recommended, and then recorded onto a worksheet.

Wooden blocks were placed on the aluminum bar. Chains were then added to smaller blocks to hang clips. The clip supported the bucket for the weights. All of the weights were pre-measured sand-bags, in sizes of 5lb., 1lb., ½lb., and ¼ lb., as well as ½ oz.


Example of the block on the jig.


Below are images of the various blocks that were provided in each of the five groups. (A detailed description of the different components in each group is in the earlier post - see above for link.)


Local spot fasteners.

Steel gauge
Powder iron in several preparation methods.
Flexible ferrite magnets.
Velcro alternatives. (Read more about this system here.)

Observations

The final section of the session was when, as a group we were able to discuss our observations of the various trials. Each group was allowed to speak. Below are the recorded comments, with some of the most important comments in bold.

Test
Test Comments
Gap Comments
Green
One group recommended, “buy the cup!” While, they also mentioned that it left a mark or impression on the paper.
The felt/batting diminished the strength of the magnet’s strength. This observation represents the whole idea of: the thicker the gap, the weaker the pull strength.
Blue
The powdered iron embedded into the batting created the best results. Groups clearly saw that the increase in the concentration of iron powder held better.
The 1” disc magnet in a cup did not hold more weight than the ½” disc in a cup on average. This was seen on all tests.
Mylar on the outside was better than when placed on the inside. This was noticed by other groups too.
Nap-to-nap surface was better. Alluding to the fact that friction can play a role in the system.
Orange
The thin foil (.001) steel did not even hold the bucket. (The average weight was 40 grams)
24 gauge steel held the cup
When the Mylar was next to the steel, it failed at ½ lb. where as, when the fabric was placed next to the steel, it stayed at ½ lbs. Other groups also noticed this.
Best results were when the suede was between and in the gap.
Red
The overall concession was that Flexible magnets do not hold much weight. One group was able to hold as much as 1-½ pounds using the 0.125 thick magnets.
All felt that the strongest was with the suede in the gap.
Yellow
Not a lot of sheer strength
Magnet needs to be smooth when using the cup
Mock-up is essential
Discussion of how to adjust the lower lip of the “L” slat.
None

Participants quickly found that the amount and thickness of the ferromagnetic material greatly affected the strength of the magnet. This was seen no matter what form the ferromagnetic material was used in: washers, steel sheet, or powdered iron. Neither the foil tape (0.001), nor the powdered iron in the paint medium was found to be strong enough to hold the bucket with any of the magnets. Large differences in magnet size did not affect the pull strength (1” to ½” was the same) (See the table below).

With using a 1/2" disc, N42 grade neodymium rare earth magnet, the table below shows the range of weight values that the range of ferromagnetic materials can support. 


.001 steel
.01 steel
.025 steel
Fender
Thick washer
Painted
Epoxy mix
Embedded batting
Less than 40 grams
½ lbs
1 1/8 lbs
¾ lbs
1 lb
Less than 40 grams
~40 grams
1/8 lbs

The activity was designed as a learning experience while also serving as a fun introduction to magnetic systems. It appears that both were achieved. Participants were able to deal with many of the issues in creating and altering a magnetic system.


While some participants had prior experience with magnets, many were experiencing the magic of magnets for the first time. Many participants mentioned to me their surprise that there were so many magnets to choose from; they had no idea of the differences in size, shape, or strength, or even what a "rear earth magnet" really was. Many participants also mentioned that before the testing they envisioned certain trials to be more successful than others. For example, many confessed their disappointment in the strength of iron powder mixed with paint as they considered it to be a more achievable method for use in their museum and hoped to use that scenario. After seeing the low hold of the iron powder and the risk for slippage of the artifact, many confided that it seemed "too risky".

The other important feedback that came out of the hands-on session was from the conservators in the green group. They immediately saw the benefit of spreading out the "magnetic force" in a system we now call "large area pressure" rather than using an individual point system (i.e. small magnets placed at intervals). Their concerns were based around the possibility of an artifact becoming indented from using a magnet that was too strong. They had only considered mounting an artifact with magnets by placing the artifact on a ferromagnetic backing and simply placing magnets at intervals across its face. Not only did the hands-on session give them appreciation of testing a system before implementing the system, but they realized that they were not limited to using magnets in one single way, instead they could consider having magnets imbedded into the wall, while having a steel strip in the artifact.

The idea of leaving a magnet in an artifact brings up a very important topic. It was not until much later and after much research that we at SAC have started to design systems where the magnet is not kept in the artifact (read an earlier blog post). This is NOT because we determined it to be dangerous (although to our knowledge there is no published information to indicate detriment or safety), but it is really about the cost of magnets and the re-usability of a commodity that currently has environmental concerns (we will not go into it here, but if you are interested, do an internet search on the mining practices for rare earth metals and you will see much of it is done in China, and that it is done in a way that is not friendly to mother earth or the people who call her home).

The use of magnets in conservation is still very much in its infancy, but with good research and sound science, we can make remarkable progress towards utilizing the exciting and great potential magnets possess. Look for more of our blog entries on magnets and conservation in the future, we have a lot to say about magnets and hope that they excite you as much as they do us!