A technical digression during #Archive30... let's talk about encapsulation, which means enclosing a flat item in a "plastic sandwich" on both sides. This can be done for items of any size, from tiny calling cards to large maps or architectural drawings. Encapsulation differs from lamination in that while a laminated item is stuck to the plastic envelope, an encapsulated item is not physically or chemically attached to the enclosure, so encapsulation is normally fully reversible. It’s recommended in the Canadian conservators’ manual, to facilitate use for vulnerable items that are handled frequently.

The below is my own considered, researched, and experienced professional opinion. As an archivist, not a conservator, I have had the privilege of working with and receiving training from excellent archival conservators in the UK. In the collections I look after, I avoid, and actively reverse, encapsulation for a number of reasons:

1) If complete, encapsulation creates a non-breathable microclimate for the contents.

2) Unless the encapsulated thing is somehow attached to the enclosure (not generally recommended) it can slide around inside the enclosure, even with the motion of pulling a large drawer open, never mind production and handling. This can damage fragile edges and corners, acknowledged in the CCI Notes.

3) Extensive encapsulation was done here as described in the CCI guidelines, by sticking two single sheets of mylar (inert polyester) together with mostly non-continuous double sided tape on the inside. Unfortunately, many of the maps and drawings have ended up with many inches of their already fragile edges exposed to adhesives and stuck to the inside of the enclosure, and to each other. If movement within the enclosure is combined with sticking to the edges, this can result is worsening existing tears and even creating new ones.

4) Inert polyester has a static charge; the CCI notes that it should not be used for friable media such as "e.g., charcoal, chalk, pencil, or pastel drawings; gouache)" but old paper itself is also friable and can be affected by static.

5) Enclosures may be doubled up back to back to save plastic sheets/volume/weight. This means any annotations on the back are not visible. The researcher should be able to see for themselves, without removing the item from protective enclosure, whether there are significant marks on the back side or not.

6) Encapsulation is sometimes done to encourage flattening of rolled items (not recommended by the CCI guidelines). This often does not have the intended result, and the item is at more risk if it changes shape inside a resisting enclosure.

Much better, including for fragile materials, is to use a card folder hinged with fabric tape on both sides of the hinge, so that no adhesive is exposed - see an example illustration at University Products. If it were advantageous to be able to view the item without lifting the top layer of the enclosure, I would use mylar for the top sheet and card for the bottom, or mylar inside the top card layer. If an item is sufficiently valuable and/or vulnerable that this is not enough protection for an exhibition, ideally it should be temporarily framed, or a facsimile displayed instead.

And that's my two cents on encapsulation. Back to#Archive30!

- Anna Sander, 14 April 2026.

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