PACKAGING FINDS

Packaging serves to contain a find or finds with important identifying information, provides physical protection from damage and can be used to create suitable environmental conditions to mitigate deterioration processes. Primary packaging includes individual find bags or boxes whilst secondary packing refers to the larger containers within which multiple finds in their primary packaging may be stored. It is usually within the secondary packaging that any specific environmental conditions required for preservation are created. Suitable packaging methods for a find will depend on whether it is to be packaged dry, damp or wet, and physical aspects such as its size and fragility.

This page offers advice on packaging of finds either dry or damp/wet finds and for temporary or medium-term storage of most find types and long-term storage of archaeological metals.

Packaging Methods for Dry Finds

Dry packaging here covers all finds that can be dried safely on site before packaging. Packaging aims to protect the finds physically and allow low humidity environments to be created where required. Although appropriate first aid for finds dry packaging advice is designed for short term use, it may be suitable for medium- or longer-term storage.

If the aim is to package for archiving, consult the receiving institution on their requirements. Where environmental control is included in the packaging, this must be monitored and reconditioned periodically to maintain a safe environment for finds.

Materials and equipment for packaging of dry finds

Common materials used for primary and secondary packaging of dry finds are given in Table 10.1. If the packaging is intended to be suitable for deposition in an archive, check the specifications that the archiving institution requires.

Table 10.1 Common materials for primary and secondary packaging of dry finds

Drying finds before packaging

Most damp finds should be dried prior to packaging if possible. Even those from dry burial contexts may have some residual moisture. Where time constraints prevent drying before packaging, this must be carried out as soon as possible.

There are important exceptions which require the input of a conservator and should not be dried on site, including:

Registered finds of any material.
Waterlogged finds.
Damp amber, jet and shale.
Damp worked ivory and bone.
Glass.

If bulk finds are to be washed on site (see Examination & Cleaning), this should take place and the finds be dried thoroughly before packaging. Types of bulk find that may be washed include ceramic sherds (not prehistoric), animal bone, and building materials e.g., stone.

General guidance for drying damp finds:

Air dry in a well-ventilated area at room temperature, away from sources of heat and out of direct sunlight.
Where large volumes of finds are to be dried indoors, it may be appropriate to use a dehumidifier to lower the humidity and accelerate drying.
If white efflorescence appears on the surface of finds as they dry (particularly ceramics, stone and bone), this may indicate the presence of soluble salts. In this case, drying should be stopped and the damp finds transferred for conservation as soon as possible.
Always check that a find is fully dry before packaging. Apply test methods to the largest and thickest finds which will be the slowest to dry:
- When holding an object in your hands, a dry object should warm up whereas one with residual moisture will continue to feel cool.
- Periodic weighing of an object as it dries will indicate when it is dry as its mass will stabilise as it ceases to lose water.
Once packaged, monitor finds to ensure that no condensation forms inside bags or boxes. This would indicate that the finds were not dry and must be unpackaged and dried fully as soon as possible.

Primary packaging of a dry registered find in a polyethylene bag

Registered finds that are physically robust can be packaged individually in a polyethylene bag (Figure 10.1). Self-sealing zip-lock type bags with white panels for marking are commonly used but heavier gauge open-top bags which must be sealed with staples are also used. Bags must be large enough to accommodate the find (or finds) without compromising the seal.

Polyethylene bags must be perforated with numerous small holes to allow air circulation. Holes must be small enough to prevent fragments of objects from passing through and can be created in various ways using: a leather punch; a paper hole punch; a spiked stitching roulette as used for leatherwork; or a nail block made by driving 3-4mm diameter nails through a block of wood.

Perforate a polyethylene bag, either zip-lock or open-top type.
Using a fibre-tipped marker, write the identifying information for the find on the white panels of the zip-lock bag. For bags with no white panels, ensure that the marker will not rub off the polyethylene.
Place a marked Tyvek finds label and the find into the bag.
Close the zip-lock or turn over and staple the open-topped bag.

Where finds require additional physical protection, polyethylene (or Jiffy) foam can be cut to fit the inside of the polyethylene bag. This supports the find and allows bags to be packed upright in a secondary container.

Cut a piece of foam of the correct size to fit snugly within the bag without compromising the zip-lock seal.
Ensure that the foam is oriented such that its ridges run up and down the bag rather than across.
Insert the foam into the bag after perforating and marking and before introducing the find and Tyvek label.

Primary packaging of registered finds using perforated polyethylene bags

Figure 10.1 Primary packaging of a registered find using various types of perforated polyethylene bags, some with foam inserts

Primary packaging of a dry registered find in a polystyrene box

Where a registered find is too fragile for packaging in a bag, it can be packaged in a transparent, rigid polystyrene box with lift-off lid and cushioned with polyethylene foam (Figure 10.2 a) or with acid free tissue (Figure 10.2 b).

Figure 10.2 Packaging a registered find in a polystyrene box with physical protection provided by a) polyethylene foam and b) acid free tissue cushions

Polystyrene box with polyethylene foam

Place a marked Tyvek finds label in the base of the box ensuring that it is readable through the base.
Cut a piece of polyethylene foam to fit the full depth and area of the box base.
Cut a recess into this large enough to fit the find, neither allowing too much room for movement nor making it tight enough to damage the find.
Place a second Tyvek label in the lid of the box ensuring that it is readable through the lid.
Cut a piece of foam to fit the full depth and area of the lid.
Insert the find into the recess.
If the find protrudes above the base foam, make the cut deeper (if the box size allows) or cut a recess in the lid foam to accommodate the find.
Carefully close the box, ensuring the find cannot move about and is not crushed.

Polystyrene box with acid free tissue

Place a marked Tyvek finds label in the base of the box ensuring that it is readable through the base.

Crumple a cushion of dry acid free tissue to fill the base of the box, creating a recess in the tissue to accommodate the find.
Place a second Tyvek label in the lid of the box ensuring that it is readable through the lid.
Crumple a cushion of dry acid free tissue to fill the lid of the box.
Insert the find into the recess in the acid free tissue cushion in the box base.
If the find protrudes above the base cushion, increase the depth of the recess or decrease the size of the lid cushion.
Close the box lid carefully, ensuring that the find cannot move about and is not crushed.

When using acid free tissue:

Do not use as a flat sheet, this will offer no cushioning for the find.
Do not wrap or roll the find in tissue, unrolling places the find at risk.
Do not use with damp finds.

Primary packaging of a large, dry registered find

Finds that are too large for a polyethylene bag or polystyrene box will need custom made packaging:

Create a bag of appropriate dimensions by heat sealing together two sheets of perforated polyethylene sheet.
Provide physical protection with polyethylene foam or crumpled acid free tissue shaped to create a pad or cushion for the find. Do not wrap or roll the find in the cushioning material.
Place a marked Tyvek finds label in the bag ensuring that it is readable from the outside.
Seal the bag either by heat sealing or folding the open end and securing with adhesive tape or staples.
Provide additional physical support by placing this bag into an archival quality cardboard box or polyethylene crate with cushioning of foam (polyethylene or polyether), acid free tissue or bubble pack to prevent movement.
Provide packing instructions attached to the packaging if the procedure for unpacking and repacking is complex.

Secondary packaging of dry finds

After primary packaging in individual bags or boxes, most registered finds will be packaged in groups of similar material within secondary packaging for transport and storage. The repository institution may stipulate the type and size of secondary packaging containers (usually polyethylene or archival quality cardboard boxes) and this should be established at the project planning stage.

The protocol for secondary packaging of dry finds depends on whether environmental control is required (Table 10.2).

Table 10.2 Materials which do and do not require environmental control within secondary packaging

Dry finds requiring no environmental control

Individually bagged registered finds or larger bags of unregistered bulk finds which do not require environmental control can be stored within acid free cardboard (archival standard) or polyethylene boxes. These boxes do not need to be airtight.

When stacking finds within these boxes, ensure that fragile finds are not damaged by the weight of other finds and that finds cannot move around freely.

Dry finds requiring environmental control

The appropriate humidity ranges for dry materials requiring environment control are given in Table 10.3. Where appropriate environmental control is provided via dehumidification in a climate-controlled room, the secondary packaging does not need to be airtight and can be as described above. Where climate control is not possible, environmental control normally employs a humidity buffer material (usually silica gel) within the secondary packaging.

The materials and equipment required for controlling humidity within secondary packaging are given in Table 10.4.

Table 10.3 Methods of controlling humidity for dry finds in secondary packaging

Materials and equipment required to create a desiccated environment within secondary packgaing

Table 10.4 Materials and equipment required to create a desiccated environment within secondary packaging

Packaging Methods for Wet Finds

Wet packaging here covers waterlogged finds that must be packaged immersed in water and those damp finds that cannot be dried on site and must be packaged in a 100% humidity environment (such as glass, jet, amber, worked bone and ivory) before conservation. Packaging aims to protect the finds physically and maintain the waterlogged or damp environment to prevent damage from uncontrolled drying (Figure 10.3). Ideally, wet storage is a short-term measure prior to treatment and controlled drying of finds or recording and discarding.

Figure 10.3 A Neolithic hurdle showing damage from uncontrolled drying which has warped and twisted the find

Materials and equipment for packaging of wet finds

Common materials used for packaging of wet finds are given in Table 10.5.

Table 10.5 Common materials and equipment required for wet and high humidity storage of finds

Minimising the risk of biological activity

Any wet storage runs the risk of biological growth which can be damaging to finds (particularly organics) and hazardous to health. Biocides are not recommended as they present health, safety and environmental risks and their alkaline pH is detrimental to materials such as glass.

Instead, reduce the risk of biological activity by:

Keeping cool – storing registered finds in a dedicated domestic refrigerator at approximately 4oC is ideal. For larger finds, or groups of finds, a refrigerated flowing water system can be used.
Keeping dark – low light levels can inhibit biological activity.
Keeping covered – limit the evaporation of water and ingress of oxygen by covering containers as tightly as possible.

Check wet packaged finds frequently for a sulfurous (bad egg) smell, green algae or black mould, which are indicators of biological activity. Change the water and repackage if biological activity is suspected.

High humidity (100% RH) techniques for packaging of wet and damp finds

High humidity (100% RH) environments can be created for the storage of damp finds by including a small amount of water or wet polyether foam in a sealed bag or box with the finds. The high humidity methods of packaging finds present higher risk than immersion techniques as a compromised seal can lead to drying out of the finds much more quickly. However, they have the advantage of reduced weight and minimal risk of spillage when transporting finds.

High humidity (100% RH) in a polyethylene storage box

Registered finds that are contained in individual perforated polyethylene bags can be enclosed in an airtight polyethylene box with polyether foam saturated in water. The water in the foam creates a 100% RH environment within the box. Follow the instructions on minimising and identifying biological activity and check frequently to ensure high humidity is maintained.

High humidity (100% RH) in layflat tubing

Larger finds can be packaged in layflat tubing, an extrusion of polyethylene, which can be sealed at the ends to create an airtight enclosure (Figure 10.4).

Cut a length of layflat tubing of the correct dimensions to contain the find and polyether foam.
Cut two sheets of polyether foam just slightly longer than the find.
Heat seal one end of the layflat tubing, checking the seal for flaws.
Soak the foam sheets in water.
Insert the lower sheet of foam, the find and the upper sheet of foam.
Include a waterproof label with the identifying information for the find.
Heat seal the open end of the tubing or fold twice and secure with bulldog clips.
Seal this with two further lengths of layflat tubing to minimise chances of leakage.

Follow the instructions on minimising and identifying biological activity and check frequently to ensure high humidity is maintained.

Figure 10.4 Primary packaging of a wet registered find in layflat tubing

Immersion techniques for packaging of wet finds

Waterlogged finds can be stored immersed in water within a polyethylene storage box or improvised container as appropriate depending on the size of the find.

Immersion in a polyethylene storage box

Small or fragile wet finds should be protected in primary packaging of polystyrene boxes or perforated polyethylene bags with waterlogged polyether foam cushioning before immersion (Figure 10.5).

Create the protective primary packaging for the finds if required.
Place the group of finds or single intermediate-sized find within a polyethylene storage box.
Fill the box with water, ensuring that the level of the water covers all finds and the finds do not float.
Close the lid tightly, ensuring a good seal.
Store without stacking the boxes as the weight of overlying boxes can distort and compromise the box seal causing evaporation or leakage.

Follow the instructions on minimising and identifying biological activity and check frequently to ensure the water level is maintained.

Immersion technique for temporary storage of waterlogged finds in a storage box

Figure 10.5 Immersion techniques for the temporary storage of waterlogged finds in a storage box

Immersion in a sealed polyethylene bag

If avoiding storage boxes full of water is a priority, individual waterlogged finds can be stored immersed in water in polyethylene bags.

Cushion and support a find within a self-closing polyethylene bag containing water.
Slowly and carefully exclude excess air from the bag by squeezing until the find is completely immersed in water.
Close and seal the bag, checking the seal is complete.
Place this bag within a second polyethylene bag.
Exclude the excess air, close and seal the bag.
Repeat to create a triple-bagged system.

Follow the instructions on minimising and identifying biological activity and check frequently to ensure the water level is maintained. If the seal is compromised, the waterlogging may be lost and the find be at risk of drying out.

Immersion in an improvised storage container

Where waterlogged finds are large or awkwardly shaped, waterproof containers for temporary storage can be improvised.

Select a waterproof container of appropriate dimensions e.g. a polyethylene window box or planter trough (with no drainage holes).
Seal with cling film, polyethylene sheeting or plastic plant trays as lids.
Attach lids using heat sealers or duct tape as appropriate.

Static containers for immersion of large finds or groups of larger finds can be constructed on site from:

Pre-formed pond liners.
Self-supporting Flexi Dam containers.
Hay bales covered with heavy gauge polyethylene sheeting or flexible pond liner.

Whichever method is used, follow the instructions on minimising and identifying biological activity and check frequently to ensure the water level is maintained.

Further Information

Boyle, G. and Rawden, A. (Editors). 2020. Society for Museum Archaeologists: Standards and Guidance in the Care of Archaeological Collections and Materials Factsheet.

Cardiff University Guidelines for Storage of Archaeological Metals. Department of Archaeology and Conservation, Cardiff University https://www.heritagepreservationguidance.co.uk/guidelines-for-storage

Cronyn, J. 1990. The Elements of Archaeological Conservation. Routledge, London, UK.

Rimmer, M., Thickett, D., Watkinson, D. and Ganiaris, H. 2013. Guidelines for the Storage and Display of Archaeological Metalwork. English Heritage.

Shashoua, Y. 2006. Inhibiting the Inevitable: Current Approaches to Slowing the Deterioration of Plastics. Macromol. Symposium 2006, 238 67-77.

Shashoua, Y. 2008. Conservation of plastics: materials science, degradation and preservation. Butterworth Heinemann, Oxford.

Thunberg, J. C., Watkinson, D. E. and Emmerson, N. J. 2021. Desiccated Microclimates for Heritage Metals: Creation and Management. Studies in Conservation, 66(3):127-153.