PMG Preservation Housing Materials and Formats
In progress: Seeking additional comments and images to develop this section
Photographic Materials Conservation Catalog
Preservation Housing Materials and Formats
Draft: Outline initiated September 2009
Contributors: Luisa Casella, Barbara Lemmen,Tania Passafiume, Stephanie Watkins
The Photographic Materials Conservation Catalog is produced by the Photographic Materials Group of the American Institute for Conservation of Historic and Artistic Works as a convenience for the membership. The treatment, methods or techniques described herein are provided for educational purposes. The reader assumes responsibility for any application results.
- 1 Purpose of Preservation Housing Materials and Formats
- 2 Factors to Consider Before Creating a Housing
- 3 Housing Materials
- 4 Effects of Housing Materials and Formats
- 5 Standards, Guidelines and Recommendations
- 6 Equipment and Materials
- 7 Housing Options and Techniques
- 8 References
Purpose of Preservation Housing Materials and Formats
Proper storage can help provide chemical and physical stability and minimize changes in the image, binder, and support from temperature, humidity, light exposure and pollution among other storage related factors. Varieties of housing materials and formats suitable for long-term storage of photographic materials are covered as the objects and the resources available to protect them varies by situation and institution.
Factors to Consider Before Creating a Housing
- The materials used for housing should be safe against photographic materials and not cause future damage.
- Materials should pass the P.A.T. (Photographic Activity Test)to establish that they are safe for silver-based photographic materials.
- The Oddy test for metals and the Fischer-Robb plastics chart can also be used to determine material suitability.
The method and approach used should take in consideration the purpose of the housing (storage, exhibition, if the object will need to be frequently accessed), the condition of the object and costs associated with the housing.
Housing materials should be chemically and physically stable, having passed the Photographic Activity Test, and have non-abrasive and smooth surfaces.
Safe Housing Materials to Use
Adhesives: Cellulose ethers, starch pastes
Paper and Boards: 100% cotton or linen without an alkaline reserve
Plastics: Uncoated and unplasticized polyester terephthalate film (brand names MYLAR Type D, Melinex 516)
'Glazing: 'Acrylic glazing is preferable to glass since the latter may break and damage the object. UV coated acrylic provides additional protection from light damage.
Potentially Harmful Materials
Paper and Boards: Buffered materials may be potentially damaging to Cyanotypes. Alkaline and neutral pH materials have been shown to fade cyanotypes under the conditions of the PAT test.
Glazing: Glass has the potential to break causing great damage to the object's surface.
Effects of Housing Materials and Formats
- Housing is essential in ensuring adequate long-term preservation of an object. It maintains the physical integrity of the object and protects it during handling and exhibition.
- It is important to consider the several levels of a housing system from the layers that are in direct contact with the object to the housing boxes.
- Housing materials create a first barrier to protect the object from the environment and may help modulate fluctuations of relative humidity and filter out pollutants.
Standards, Guidelines and Recommendations
- ISO 18902:2007 Imaging materials – Processed imaging materials – Albums, framing and storage materials
This international standard specifies the chemical and physical requirements for all housing materials which are in direct or close contact with photographic materials. These include all paper, paperboard, and plastic sleeves, envelopes, folders, mat board, boxes, interleaving, slide mounts, framing materials, and other formats. [ The introduction to the standard does not mention many common photographic processes, the component(s) of which are known to be pH sensitive, including dye transfer, cyanotypes, salted paper, albumen, collodion, platinum, and diazotypes; this omission implies that buffered storage materials should not be used. Research supports avoiding buffered materials in contact with cyanotypes; alkaline and neutral pH materials have been shown to fade cyanotypes under the conditions of the PAT test. There is anecdotal evidence of contact with buffered housing materials, even under ISO recommended environmental conditions, causing deterioration in some of the photographic processes in this list. However, there is no consensus in the photographic conservation community concerning processes other than cyanotypes.]
- ISO 18916:2007 Imaging Materials–Processed imaging materials–Photographic activity test for enclosure materials
The Photographic Activity Test or P.A.T. [] was developed by the Image Permanence Institute and became ISO Standard 18916. The P.A.T. is an accelerated aging test which incubates, at high temperature and humidity, samples of the product in question with the basic components of photographs. Any change indicates that the product might degrade photographic materials stored in or close to it. You should select products which the manufacturer has tested with the P.A.T. Materials which pass the P.A.T. do not automatically meet the criteria in the first ISO standard; however, you can usually assume that a product is safe to use based on this test along with a general knowledge of the ISO standards.
- Necessary Qualities
- Material is chemically and physically stable
- Construction of enclosure is sound and sturdy
- Surface is smooth and non-abrasive
- Passes the PAT
- Additional Criteria for PAPER PRODUCTS
- High alpha cellulose content from rag, cotton, and/or chemically purified wood pulp
- pH of 7.0 to 9.5 + 0.2
- Buffered = alkaline reserve of 2% or more calcium carbonate or chemical equivalent
- “Lignin free” (< 1%)
- Minimum of alkaline or neutral pH sizing, e.g. no alum-rosin sizing
- No metal particles, waxes, or plasticizers
- Less than 0.0008% reducible sulfur
- Colorants are non-bleeding
- No glassine or magnetic albums
- Album covers need not pass the PAT or meet all criteria if not in direct contact with photographs
- Additional Criteria for PLASTIC PRODUCTS
- Inert, stable
- Minimal plasticizer content
- Minimal slip and antiblocking agents
- Poly(ester terephthalate) is always a good choice: it is the most inert, dimensionally stable, and rigid
- Poly(propylene), poly(ethylene), poly(styrene) or spun-bonded poly(olefin) are generally suitable
- No cellulose nitrate, cellulose acetate, or PVC-poly(vinyl chloride)
Equipment and Materials
- Board shearer
- Window mat cutter
- Bone folder
- Teflon Folder
- Uncoated poly(ester terephthalate film (e.g. Mylar-Type D or Melinex 516)
- Silversafe paper
- Double sided tape
- Framer's tape (with aluminum core)
- Linen gummed tape
- Tyvek tape
Housing Options and Techniques
There are a variety of options that may be used for housing photographic materials with different complexity levels. Housing techniques may be determined by intended use of the object (storage, display), condition, and budget.
Paper vs. Plastic for Enclosures
- Advantages and Disadvantages to PAPER
- Easy to label
- Porous, breathable, absorptive – preferred for deteriorating negatives
- Opaque - decreases light exposure but often leads to more handling
- Advantages and Disadvantages to PLASTIC
- Visibility reduces handling but increases light exposure
- Non-porous – prevents cross contamination with poor quality materials, such as sticky tapes
- More durable than paper
- More rigid ones provide additional support for weak/brittle objects
- Electrostatic charge - keeps thin or light objects from shifting but attracts dust or can lift off flaking or friable media
- Photographic prints may be matted, housed in uncoated poly(ester terephalate) film (e.g. Mylar Type-D or Melinex 516) enclosures or horizontally in boxes separated by interleaving material.
- Prints may be secured to the mat in a variety of methods, preferably using corners that prevent having to apply adhesives to the original. The use of folded paper corners attached to the mat with wheat starch paste or methylcellulose is a method that allows to easily remove the print from the mat by opening the corners, without stressing the edges of the print (that may occur when using polyester corners).
- When housing prints in mylar enclosures a piece of matboard slightly larger than the object should be inserted behind the print to add rigidity and protection during handling.
- Sealed packages may be created to house matted objects together with the glazing and an impermeable backing. A variety of barrier materials may be used to create different packages such as impermeable to moisture, pollutants or even to create a completely impermeable package such as an anoxic package. *Scavenger materials may be included in these packages that will absorb moisture, pollutants or oxygen. Color changing indicators, visible from the outside of the package may also be included to indicate relative humidity or oxygen levels.
- Cased photographs may be housed in metal edge boxes, several to a box separated by matboard, ethafoam or felt. Alternatively, cased photographs may be housed in [Solander boxes] in an ethafoam tray with spacers to prevent shifting while handling the box. Cased objects are often housed in custom made tuxedo boxes and are then housed inside metal edge boxes or Solander boxes.
- Glass transparencies may be housed in a sink-mat. The use of earth magnets to keep the mat closed helps secure the object.
- Andrews, Kim. Matting and Framing Specifications for Objects on Paper. []
- Curry, Lynn and Tania Passafiume. Instructions: Adhesive-freeSpacer/Cale de carton ondulé sans adhésif. Library and Archives Canada/Bibliotèque et Archives (2010) p.1-9. PDF Presentation at the 36th Annual Conference/36ième conférence annuelle Canadian Association forConservation of Cultural Property/l’Association canadienne pour la conservationet la restauration des biens culturels June/juin 10-12, 2010.
- Lemmen, Barbara. Housing Materials for Photographs: Criteria for Selection. []
- Phibbs, Hugh. Recent Developments in Preservation of Works on Paper. The Book and Paper Group Annual 24 (2005) 47. []
- Rose, Carolyn L. and Amparo R. de Torres. Storage of Natural History Collections: Ideas and Practical Solutions, Vol. II. Society for the Preservation of Natural History Collections (1992, 2002). See particularly collection of instructions published individually elsewhere:
- CCAHA. Enclosure for Broken Glass Plate Negatives, 155-156.
- Nishimura, Douglas W. Storage of Polaroid Black and White Photographs, 275-276.
- Smith, Merrily A. Matting and Hinging Flat Paper Objects, 134-138.
- Wagner, Sarah S. Enclosures for Glass and Film Negatives and Lantern Slides, 141-143.
- Wagner, Sarah S. Storage of Large Paper Objects, 277-278.