What to do with Three-Dimensional archival objects?

By Gwen Spicer 

The majority of our posts this month (aka: "October is Archives Month") have focused on storage relating to flags which also fit in nicely with the NAVA annual meeting which took place October 11-13. It is true that flags can be found in Archives, however, the typical material that Archivists handle and need to store are flat materials consisting of documents, historical records, and photographs. These materials fit neatly within the standard document box, or smaller version: the document case.

Many museums or historical societies use document boxes or cases for storage, simply because they are standard sized, or perhaps it is the type of box which they have the most need for, or maybe it fits best within their storage area.

Row upon row of Storage Cases - the smaller, upright, top-loading style of the document box.

Several years ago I was asked to speak to an Archives group regarding 3D artifacts. (Yes, 3-Dimensional items are archival items). Flat items are the typical materials to be found, but certainly 3D items need an archival home as well. In preparation for the workshop, I created solutions for possible 3D materials that could fit within standard document case packaging found in an archives storage facility. Below is a short video highlighting the retrofitting of a document storage case to hold 3D objects, as well as 2D objects, because yes, sometimes they can live together in one tidy storage case.

Many of the archivists present at the workshop mentioned that their archives would not be complete without the 3D items in their collections and that these items rounded out the document collections in that they gave depth to exhibits, making them more eye-catching. And sometimes the documentation exhibited required the 3D objects to illustrate more clearly the display, for example, one archivist had extensive textiles and bottles to accompany the documentation of early medical training at a nursing college.

Archival boxes, also referred to as document boxes, in the storage area.

The most valuable part of utilizing a document container as multi-dimensional storage, is making sure that the transformation of the box was easy to do and would involve only the tools and materials any archivist or conservator would have on hand, and use a technique that would be easily known (i.e. cutting mat board, acid free materials like twill tape)

The multi-dimensional document box/case storage provides excellent accessibility, while significantly limiting excessive handling, as each item can be removed independently of the others. Many workshop participants appreciated the concern for handling, as reduced handling of archival items is crucial to their integrity. Yet, having access is to archival items is key.

In the prior post, How to Store Your Flag Part 2 - The Sink-Mat, the sink-mat can be used to great effect. Remember that smaller sink mats can be placed horizontally by stacking them inside the box, while remaining flat. For this particular solution, a specific document box is required - the clam-shell or print box, with a drop front. Available through all archival suppliers, these boxes are meant to lay flat on the shelf, and when the lid is lifted, the front side of the box drops forward, thereby allowing full access into the box without moving the box - it is truly the perfect archival home for a sink mat!

We hope you have enjoyed October, and all of our posts about archival storage, as much as we have.  Look for more videos from SAC in the coming months, our next video will cover how to properly roll textiles.

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Gwen Spicer is a textile conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.

Glossary of safe materials for storage

How to Store Your Flag parts 1, 2 and 3 have been met with lovely comments from old friends and colleagues as well as some new friends and colleagues, I'm so glad these were useful.  In this series of posts on storage we mentioned many materials. We thought that it would be helpful to just post the entire list of materials in one location, so as promised, below is the glossary - enjoy!

Acid-free tissues, papers and boards:
Acid-free or neutral pH materials should always be used. These materials are made of 100% cotton fiber, whereas acidic papers are made from wood pulp. Questionable materials can be tested with pH indicator pens. These pH pens can be purchased at archival supply, or craft and fabric stores.

The blue/gray boards have a buffering agent added. It is generally an alkaline substance with a pH over 7. This reservoir neutralizes the acids that may be absorbed from the environment around. The alkaline residues could react with protein materials, like wool, hair, leather and some photographs.

Buffered materials can be used for Cellulose materials, like paper, cotton, and linen, but not with proteins. It has been observed that being in contact with buffered tissue also affects some dyes. Therefore care is needed in choosing the correct material.  Use for interleaving, solid supports, and in storage containers

Adhesive Tapes (Double-sided):
As with plastics, tapes need to be chosen with care. A product by 3M, #415 double-coated tape has been found to work best. It is pressure sensitive made with a high tack acrylic based adhesive on a polyester carrier. Products #924 and #969 are acrylic-based adhesives with no carrier. Both are non-yellowing, inert and reversible with solvents. Both tend to cold flow.

Use these tapes only in construction of storage supplies, like encapsulating flat paper items, but not placed directly on the artifact.

Batting:
Look for polyester needle-punched batting. This batting is formed mechanically by fiber entanglement using barbed needles. The other commonly found battings are made with resins that bond the fibers. The resins have been found to yellow and then can transfer onto artifacts. The packaging will frequently be marked if one is purchasing from a fabric store. Polyester materials resist mildew.

Use batting for padding-out and filling in order to obtain the desired profile of a mannequin. It can hold shape even under weight. Best if secured with stitching. Can also be used as stiffening, like at the bottom of a petticoat. Note that all battings need to be covered.

Coroplast:
A rigid, lightweight, polypropylene/polyethylene copolymer corrugated (or fluted) sheet. It is lightweight and fairly strong. The archival grade does not have any anti-static or ultraviolet inhibitor additives. This grade is more expensive than the standard grades. Coroplast can be cut with a utility knife. It can be bent with heat, or scored. Sheets are available in several thicknesses, 2-6 mm, and in several colors. When used for storage box tray construction, the sides can be secured with brass clasps, and sewn with heavy weight cotton, linen thread or twill tape. Corners can also be secured with hot melt glue rivets.

For display, one can cut it into forms to support lightweight textiles. Cover Coroplast with batting and stockinette or exhibition fabric.

Ethafoam:
Ethafoam is a Dow Chemical Co. trade name for polyethylene, a thermosetting plastic. Ethafoam is a closed-cell foam with a smooth surface. The cut edges are softer than other foams, like Styrofoam. It is easily cut with knives, and wood working tools.

It is best to look for Ethafoam manufactured by Dow. Other foams have been found to include additives and stabilizers that can cause problems and yellowing.

Fabrics:
It is best to use unbleached 100% cotton fabrics, like muslin, stockinette, flannel and twill tape. Any fabric that is used with collection needs to be washed in hot water.

A word of caution about fabrics; many have finishing treatments like flame-retardant or durable press. These types of finishes need to be avoided and removed with hot water washes. Wool is also a fabric not to be used for exhibitions or storage. It can tarnish silver in closed environments and attracts insects. If felt is to be used, look for polyester types.

Foam-Core:
A Styrofoam sandwiched between paper or plastic. There are both archival and non-archival products available. These come in several thicknesses. Avoid using cores made of beaded Styrofoam, as the beads can easily break apart at the edges. Best to use as a temporary material. Not suitable for long-term storage.

Hook and Loop Fasteners (Velcro):
Not all-generic Velcro is made from the same formulation. Some forms of Velcro have been found to have adverse effects to the textiles to which they have been attached. It is suggested to purchase it in large batches and test it. Always attach the soft side to the textile artifact with a separator of webbing or a muslin tab.

Avoid using Velcro with pressure-sensitive adhesive.

Hot Melt Glue:
This is a thermoplastic adhesive that is applied in the molten state and forms a solid when cooled. There are several different formulations. The ethylene/vinyl acetate copolymer is generally suitable for construction of mount supports. 3M’s #3764, Bostik’s Thermogrip #6363 and Evode’s Evo-Stik #7702 have been found suitable.

The glue is very hot! Care is needed not to burn oneself. It adheres to most surfaces. It can be difficult to use with smooth surfaces. Can cause damage to rare earth magnets.

Marlvelseal #360:
A foil composed of layers of nylon, aluminum and polyethylene. Provides a good barrier that resists transmission of water vapor and gases. The polyethylene side or dull side can be heat-sealed and can conform to curved shapes with a tacking iron. Use Marlvelseal to seal questionable materials for display and storage.

Mylar:
Mylar-D is a polyester, transparent film. It is a strong, inert and dimensionally stable film that is very clear. It comes in different thicknesses. Look for virgin polyester, type D made by DuPont Co. Mylar does create static charge.

Use to encapsulate and separate materials.

Plastics:
Not all plastics are the same. Many have plasticizers that make the plastic material more flexible. Over time the plasticizer causes deterioration and should be avoided. Other additives that can be included and can cause damage are slip and anti-static agents. Dry cleaning bags turn yellow due to BHT that is added to the polyethylene.

Good plastics are made from polyethylene, polyester, polypropylene and acrylics. These are the most commonly found. Most archival products found in catalogs will be made of one of these types. Other less common plastics are: polytetrafluoroethylene, polycarbonates and silicone.
Plastics that cause adverse effects are materials and rubbers containing sulfur-vulcanizing agents.

Stockinette:
This comes as 100% cotton unbleached or 100% polyester surgical tubing. Both need to be pre-washed. It is used to cover mounts, tubes, etc. It is particularly useful in making arms and other sausage like shapes. It provides sufficient tension to lower the amount of stitching needed.

Tyvek:
A spun bonded olefin is a high-density polyethylene fiber bonded under intense heat and pressure, manufactured by DuPont. This product has many good qualities: it is strong, non-buffered, has low resistances to water and mold. Tyvek both protects artifacts from dust while allowing for air circulation. It is smooth with no binders, fillers or buffers. It is low linting, and resistant to water and chemical-aging. Some solvents cause swelling. Housewrap may contain ultra-violet stabilizers. It comes in a range of weights. The weight that is commonly used is Type 1443R. This material can be washed in the washing machine several times. It is good for dust covers and wrapping collections. Can be seamed or glued. However, is not a good barrier for preventing acid migration.

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Gwen Spicer is an art conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.

Look for Gwen's book, "Magnetic Mounting for Art Conservators and Museums",  available in 2018.

How to store your flag, Part 3: Rolling

As stated earlier in "How to Store Your Flag, Part 1" proper storage is critical to the long-term preservation of any collection. Proper storage includes safe materials that are acid-free, a stable environment, protection from light, minimal handling, etc.

Rolling of textiles is an excellent option for flat, single layer, artifacts that are too large to be stored “flat”. Any rolled storage consists of four main parts: the tube, an internal support for the tube, the leader, and the outer wrapping. Specifically, for flag storage, the length of the tube is determined by the height of the flag, plus additional space for the securing of the outer wrapper. Remember that the hoist edge will run the length of the tube and will be rolled last. The tube and its textile is then supported on cradles, or in storage furniture.  Grouping your collection into standard sizes maximizes space and budget.

Illustration by Gwen Spicer of the various layers of rolled storage.

A paper, or muslin, apron is used to assist in the initial rolling of the textile. The textile can be interleaved with acid-free tissue, muslin, or cotton sheets for larger textiles like rugs. The textile is then covered with muslin or Tyvek and secured with twill tape ties.

The diameter of the tube needs to be considered with several factors in mind. The larger the tube, the better it is for the flag. However, there is always a balance among space, budget constraints, and the size of a collection. Unfortunately archival tubes are very expensive specialty items because tubes used for rolling textiles need to be made of acid-free cardboard, which is made from virgin materials.

A small lightweight flag can be stored on 2" diameter tubes. Medium size textiles are best on 3" diameter tubes, and heavier flags require even larger tubes, which may also need to be supported by metal rods. Part of the tube’s diameter selection is the degree of bend, or angle, that the fibers are required to conform. Over time, the fabric can have a memory of the curvature.

Cutting tubes for a collection of flags.

Cradles are an integral part of rolled storage. If the rolled textile were allowed to rest on a solid surface, the point of contact between the surface and the artifact would result in stress, not just to the outside layer which runs the length of the tube, but to each layer beneath the outside layer. The weight of the textile and the storage supplies can easily crush and cause damage to fragile textiles. By raising the ends of the tube above the surface just slightly, this can be prevented. Cradles can be easily carved from Ethafoam. Ethafoam is a Dow Chemical Co. trade name for polyethylene, a thermosetting plastic. Ethafoam is a closed-cell foam with a smooth surface. The cut edges are softer than other foams, like Styrofoam. It is easily cut with knives, and wood working tools. It is best to look for Ethafoam manufactured by Dow. Other foams have been found to include additives and stabilizers that can cause problems and yellowing, these obviously should be avoided.

They can even be stacked, or with notches, placed in a row side by side. The cradles need to be positioned at the end of the tubes, away from the flag itself. Stacked cradles are useful when a small group of unusually sized tubes are needed, and it is cost prohibitive to purchase furniture for such a small collection.

Detail image of carved Ethafoam cradles for two flags.

The cradles were designed for the flags to be stacked. The locations
where the tube rests on the cradle is outside or beyond where the
artifact is located. The pressure of the cradle is only on the tube
and outer wrappings itself.

Shorter length tubes can be placed in boxes, or drawers supported with Ethafoam cradles to suspend the tube above the bottom surface. Care will be needed to ensure that the tubes are cut to accommodate the inside dimension of the drawer or box. This is especially true with long and bulky textiles that can become large in diameter as their length is rolled. Tubes within boxes or drawers can run either direction to provide more options for tube length. These shorter tubes do not require an internal metal bar for support like the longer tubes. Please note any cut end of tubing often needs to be sanded lightly.

Rolled textiles suspended in the storage drawer with Ethafoam cradles.

Flags rolled and suspended on cradles that are positioned onto shelves.

On occasion, a longer tube is necessary. To make a longer tube, an insert is made from a scrap tube section approximately 8" or 10" long. A cut is made along the entire length. (For thick-walled tubes, the cut needs to be the thickness of both walls.) One half of the scrap tube is inserted into the tube and its extension. These longer tubes will also need more attention paid to placement within the storage room. Each tube will need to be maneuvered through the storage room's door, possibly around cabinets to its designated location. These heavy textiles will need to be supported by metal rods.

There are several collections that use Mylar with the prospect that the artifact can be seen through the storage covering. This is an advantage. However, there are two main disadvantages, one is the static-charge inherent in the Mylar and the other is the potential of fading in the exposed area. If plastic is deemed necessary due to pest concerns, then Polyethylene tubing as the covering is a better choice. There are many collections that use Mylar as their outer covering to aid in seeing the artifact, but this conservator discourages this choice.

It is important to note that Mylar would not be fitted into another tube as that it creates surface abrasion. In addition, if the receiving tube is too small, it can crush the flag inside. Other drawbacks are that there is limited access to the rolled flag, and, when it is slid in, one does not know if it remained smooth or if it is bunched.

Flag Storage has many facets, to this point we have covered several methods of storage. Many terms have come out of these reviews of storage, in the next posting we will include a full glossary of safe storage materials.
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Gwen Spicer is a textile conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.

How to store your flag, part 2: The sink-mat

by Gwen Spicer

Welcome to part 2 of flag storage!  I find that often flag storage focuses around larger flags. We lament how much storage space they require, the sometimes inevitable need to fold them because of their size, and how to access or display them - again because of their size. But what about the small things like flag fragments or small parade flags or even artifacts like political ribbons and the like? It is these smaller things, and especially textured or unevenly surfaced artifacts, that will benefit from flat storage in sink-mats.

Storing a flag or other artifact is determined by many things as discussed in part 1 of flag storage. But determining storage needs can also be done in a very simple way, and that is by basing it on size. For smaller flags and related textiles, sink-mats are a perfect solution. Actually any small to mid-size textile can be stored, and then easily accessed from storage with this design. Such textiles might also include samplers, embroideries, printed textiles, etc. They allow for the smaller textile to remain flat, while being supported and protected. This is especially useful when one is trying to avoid the compressing of any delicate raised areas, fringe, embroidery, and similar. 

The design is very much a variation of "matting" used for prints and drawings. In fact, the first designs for textiles were window mats that were cut around the textiles. The design described here uses less materials and can be simply done and without special tools, such as a mat cutter. The design includes strips of acid-free board to accommodate the thickness of the textile with a board cover that is secured with twill tapes. The flag or textile can be tied to the board or sandwiched between muslin and tissue paper.

Illustration by Gwen Spicer of a sink-mat

The images below represent various sink-mat views. The first is overall, and then details of the design for a small silk ribbon. Protective covers can be easily incorporated into the design. 

Sink-mats can also be designed with protective lids.

The next two photographs are for a larger textile and its associated wooden rod. The same design is used, just with sturdier materials. Lincoln's banner is supported with double-walled corrogated blue-board. Larger sized sink-mats sometimes require thick flutted plastic, like Coroplast. This material can be sturdy and provide necessary support, while also remaining light-weight.

The Lincoln campaign banner and the smaller parade flags retain their staffs. These too can be incorporated into the sink-mat design.

Drawer storage with several sink-mats.

Large sink-mat holding several associated artifacts in a single sink-mat.

Sink-mats are also often suggested as a best storage solution for photographic materials, like daguerrotypes as well as other photographic items. Sink-mats are desirable as a means of storage for a variety of objects simply because the result of their use is a collection that is accessible to researchers, and it can be viewed with very little handling. In addition, the items placed in sink-mats are free from the threat of compression.

Coming up next in Flag Storage we will discuss rolling. Look for the blog soon, or sign up in the right side margin and you will automatically receive the blog delivered to you via email.

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Gwen Spicer is an art conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.

How to store your flag, Part 1

by Gwen Spicer

We have recently had many calls about how to store and care for flags.

Proper storage is a critical part of all collections housed in institutions, as well as those in private collections. Proper storage is really the best means for long-term preservation. The goals of storage are to provide proper support and environment. Flags and other types of artifacts deteriorate from poor handling and lack of archival materials, high light levels, mold, pests, temperature and relative humidity, and inherent vice. It is the role of proper storage to lower the effects of these modes of deterioration.

A useful way to approach any storage, whether archives, libraries, or museums, is to think of it as a “a box within a box with in a box” The first level of "box" is the building itself, then the room, then the storage furniture, and last is the possible boxes that contain each item. Each layer of protection enhances the environment of your collection. Large fluctuations in temperature and relative humidity are diminished with slower transitions; and pests are further prevented from getting to the flag. This is especially important for organic materials like silk, wool and/or cotton.

Chrome-plated wire shelving from Metro-International used to store a
collection of banners from the Chautauqua Institution, Chautauqua, NY.

Care is needed when selecting materials used for storage. (See last weeks post, "What is acid-free?") As stated earlier, they can either assist in the preservation or deter. Poor quality materials can cause acidity, off-gas, and discoloring, among other effects, that deteriorate collections. To prevent these types of damage, good quality and acid-free material should be used.

The ideal method is to keep your flags as flat and fully extended as possible. Flags and textiles that need to be flat have several options that include: sink-mats, boxes, or shelves. In many circumstances, placing the flag on a full support is recommended. This is especially necessary with flags made of silk. Silk, as it ages, becomes less flexible and prone to splits and fractures. A contributing factor to the deterioration of silk is its past history, like its exposure to sunlight.

Oversize shelving by Crystallization.

The supporting material can be muslin, or Tyvek (see earlier post "What is acid-free?"). For fragmented flags, placing a layer on top is also recommended. The support allows the flag to be moved and handled without damage. The material used for the support is determined by the conditions. The poorer the condition, the sturdier the material should be. The support should be continuous over the entirety of the flag.

Museums often have available space for large storage units. Also, many museums have the storage facilities to accommodate large units outfitted with full sized pullout drawers or shelves. The designs of these units vary in detail and perhaps construction materials. However, they all allow a flag to be fully extended and visible to the researcher. Since flags often come in standard sizes, standard sized storage units can be used.  However, when a collection consists of a variety of flag sizes, having a range of sizes of units utilizes the space efficiently. This can best be achieved with full knowledge of your collection and the dimensions of each flag in it. Units are designed both for the flags to rest in a pre-conserved state, or on their display mount after conservation. The later allows for easy rotation of the collection. Below, as well as the two photos above, are a sampling of flag and banner storage in museums.

Mounted flags at the Maine State Museum, Augusta, Maine. Each flag was
secured to a prepared panel (aluminum honeycomb) and had a place within a
the rack. The panels and rack were made by SmallCorp, Inc., Greenfield, MA.

Determining appropriate storage for a flag can be done by answering questions about the object itself.  The following questions and their corresponding answers are meant as a guide. It is understood that specific situations exist that may not easily fit into these guidelines. These first 10 questions are about the flag and therefore suggest what kinds of storage to consider for an individual flag.

Q: What is the age of your flag?
A:  The age of the materials that compose a flag greatly affect the method of storage to select. Older flags need more protection and support. Therefore it is important to realize that the better the storage early on, the better the preservation in the long-term. Early flags that have been kept off display remain in far better condition than those that have been exposed to poor environments.

Q:  Is your flag made of silk?
A:  Silk becomes quite brittle with age, loosing its flexibility. Of the natural fibers, silk is the most dependent on its environment.  Flat storage is preferable for silk flags.

Q:  Is your flag made of cotton?
A:  Cotton is susceptible to moisture and mold growth.  Cotton flags benefit from being stored in a box or rolled.

Q:  Is your flag made of wool?
A:  Wool is most susceptible to insects, like webbing cloths moths and carpet beetles. Protection from these insects is critical. Boxing or rolling these flags is suggested.

Q:  Is your flag made of Nylon or other synthetic material?
A:  Many synthetic materials are easily degraded in sunlight, whose affect is not fully realized for several decades later. Caring for these flags now will only lengthen their preservations. Flags from WWII and the Korean War are deteriorating and are becoming weakened.  This type of flag benefits from rolling or boxed storage.

Q:  What is the condition of the flag?
A:  Being able to evaluate the condition assists the determination of the flag’s storage needs. The condition of the various materials that the flag is composed of is critical.

Q:  Has your flag been treated previously?
A:  Treated flags often have additional supporting layers that prevent the flag from being rolled. In additional, early treatments can contain materials where their aging properties were not well understood and are possibly brittle presently. Learn the date and materials used in the treatment. It is best to follow the instructions of the treatment.  These flags should be stored flat.

Q:  Are painted surfaces present?
A:  Paint layers, as they age and become dry are no longer flexible. When flexed they crack and are vulnerable to flaking.  These types of flags must be stored flat.


Next week look for the continuation of our discussion about flags and storage.  Rolled storage is an art all its own, we will take a look at it, and answer a few more questions and answers to determine when rolling is wise and when it should be avoided.
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Gwen Spicer is a textile conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.

What is acid-free?

by Gwen Spicer

October is "Archives Month" and we at Spicer Art Conservation, LLC are celebrating the month by discussing some storage topics. In an earlier post we talked some about environment (see "It's Spring and it's Dry?").  This post will focus on selecting the materials which are within closest proximity to your artifacts.  Whether it be storage, support, or display materials, these materials will almost always be in contact with an artifact and should always be acid-free.  

Care is needed when selecting materials used for storage. The materials selected can either assist in the preservation or deter it. Poor quality materials can cause acidity, off-gas, and discoloring (among other effects), that deteriorate collections. The results of poor quality materials are not immediately observable and so their damaging affects will not be apparent until it is too late and the damage has been irreversibly done.  To prevent these types of damage, good quality and acid-free materials should be used.

An acid-free box with "artifacts" waiting to be stored.  The tray is made of ethafoam, the lifting handles are made of twill tape.  All items are acid-free, of course.

So what is acid-free?  They are materials that are a neutral pH of 7.  There are two methods to reach this pH 7. One, is to begin with naturally, inherently neutral, pH materials, like 100% cotton fiber.  The second method is to begin with a wood pulp or other acidic material and buffer it until it reaches a pH 7. The disadvantage of buffered wood pulp or any other acidic material is that the buffering eventually becomes exhausted and then the product returns to being acidic. Buffering can be done in more than one way, yet each way will always result in temporary buffering. Calcium carbonate or other buffering agents can work, but how long do they last?  Is the length of its buffering ability effected by the environment that it is stored?  Too many unknowns exist in using this method, best to not use it at all.

Yes, archival materials are expensive, which is a result of their being made from pure-virgin materials. As framers, collectors, and other private owners of art become aware of the benefits of high-quality materials, the buying audience becomes larger, thus the price does drop. The down-side to true archival,  pure-virgin materials is that is not conducive to the new "green" society that we are moving to where recycling is encouraged. To find out more on sustainable practices read about it on the AIC wiki page by clicking the link.

But back to storage using archival materials. An important part of safe storage is using safe materials that do not cause further damage. For example, direct acidic contact causes yellowing and localized brittlement. The shelf that the box rests on, if wooden, can also affect the archival integrity of the box which houses the artifact over time.

pH indicator pens can be purchased from any archival supplier.

The use of a pH pen is a good idea for testing your shipments of archival materials or the materials you already own.  The reason for this is that one can not be sure of purity, particularly of archival materials that are old.  The paper and boards used are absorbent and over time are effected by their environment.  So, if an acid-free box is sitting on a uncoated wooden shelf, over time the bottom of the box will have absorbed the acidity of the wood and will no longer be acid-free. Even the inherently acid-free nature of cotton rag cannot stay acid-free in that environment.  Therefore, the pen will give you an indication of when boxes or other storage materials might need to be replaced. Unfortunately, no FDA or other “watch-dogs” exists for archival materials. So, it is the buyer who must beware. I always use the motto of “if it is too good to be true, then it is.”

Wood remains a common material in storage construction, due to its cost and ease of use. However, wood has inherent volatile compounds which off-gas and cause damage to organic materials. Each wood specie has a different rate, hard woods emit (especially oak, for example) more than soft woods. Newly milled wood emits more than older wood. But it is important to remember that wood emits acid throughout its life, until it is  fully degraded and no longer viable for any purpose. If new wood needs to be used, only Poplar is recommended. It is the lowest acid-emitting wood available. Wood is not just in furniture, be aware of it's use in other ways: the jacket below for example.

The evidence of the wooden hangar that this coat hung from is unmistakeable.

As stated earlier, no liquid applied barrier fully prevents acid migration, only an applied film will do so. Mylar and Marlvelseal can easily be used to line wood shelves or the inside of wooden drawers.

Marlvelseal is a foil composed of layers of nylon, aluminum and polyethylene. It provides a good barrier that resists transmission of water vapor and gases. The polyethylene side or dull side can be heat-sealed and can conform to curved shapes with a tacking iron. Use Marlvelseal to seal questionable materials for display and storage.

Mylar is a polyester, transparent film, that is a strong, inert, and dimensionally stable film that is very clear. It comes in different thicknesses. Look for virgin polyester, type-D made by the DuPont Company. It is helpful to note that Mylar does create a static charge. It is most commonly used to encapsulate and separate materials by interleaving.

A wooden drawer lined with a layer of Marlvelseal. It is a true barrier
 against the migration of acids from the wooden drawer. All of the
sides and bottom of the drawer are covered.  The tape used to secure it to the drawer is linen tape.

Now onto the drawer itself and the rest of the storage containers and furnishings. Whether you use drawers, shelves of a combination of both, the selection of materials for these units or any other storage furniture is performed with consideration of materials that do not off-gas or cause other damages to the collection. Safe materials for furniture include aluminum with a powder coating, anodized aluminum, and steel with powder coating.

Sometimes acid-free tissue is not enough. Compare the knives side by side above.  the one on the right was wrapped in acid-free tissue, the one on the left was wrapped in Pacific Cloth, a cotton-flannel with scavengers (more on scavengers later) which remove the sulfur dioxide from the air and prevent tarnishing.

Certainly not everything in a collection fits neatly into boxes, on standard sized shelves, or into drawers.  These items, rugs, large flags, tapestries, and large textiles to name a few, often require rolling onto tubes and storage of those tubes on acid-free supports. At times, acid-free tubes are not used due to budget restraints, in this case, a layer of Mylar or Marvelseal over the standard cardboard tube is required. Mylar is secured to the tube with double-sided d-tapes, (3M #415). Marvelseal can be heat sealed to any surface. These materials are barriers against the migration of acidic products from the standard tube to the artifact. A word of caution, while they may seem like a good idea and cost effective, liquid shellacs and paints do not sufficiently provide the same amount of protection, and should be avoided. Think of the old adage: "Do it right the first time".

An example of ordinary plastic dry-cleaners bags over time. These pieces are yellow
and a crumbling due to their brittleness. 

Above I mentioned a diversion from "green" practices, when we discussed virgin materials. I will make up for that here by suggesting a very green practice: Substituting acid-free tissue with washed cotton muslin or cotton sheets. Cotton sheets make excellent handling slings, they provide support and diminish the direct handling of an object during transporting. The benefit of their use as handling slings is that they can be washed and reused, whereas the tissue is just thrown out.

Another great material is Tyvek. Tyvek is spun bonded olefin which is a high-density polyethylene fiber bonded under intense heat and pressure, manufactured by DuPont. This product has many good qualities: it is strong, non-buffered, has resistance to water and mold. Tyvek both protects artifacts from dust while allowing for air circulation. It is smooth with no binders, fillers or buffers. It is low linting, and resistant to water and chemical-aging. It comes in a range of weights. The weight that is commonly used is Type 1443R. This material can be washed in the washing machine several times. It is good for dust covers and wrapping collections. Can be seamed or glued. However, while it is a good acid-free material, it is not a good barrier for preventing acid migration. Also, some solvents cause swelling. Tyvek used in archival applications should never be confused with Tyvek Housewrap, used in the building industry, as house wrap may contain ultra-violet stabilizers and coatings.

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Gwen Spicer is a textile conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.