Tips - Acid-Free Tissue
Occasionally, it is good to re-evaluate common practices: to question objectives and determine if methods and materials can be improved.
Acid-free tissue is widely used in the storage of objects to protect and cushion delicate materials and to act as a barrier layer when interleaved. It is considered a material of 'archival quality' which implies that it is suitable for use in conservation. However, the term is not quantifiable even though it is accepted as being chemically stable, and as a result, resistant to harmful environmental conditions. Therefore, as conservators and custodians of historic objects we have no idea how long acid-free tissue remains acid-free. So, even though we may not know exactly how long acid-free tissue is safe to use, we are able to make an informed choice as to the most appropriate form of the material to pack and protect objects.
There are two types of acid-free tissue: buffered and unbuffered. Of the two materials, buffered tissue is more opaque as the surface is coated with calcium carbonate. This is added to help neutralize additional acids that migrate from a soiled or degraded object. It is recommended that this form of tissue is used with cellulose based fabrics such as cotton or linen. Conversely, unbuffered tissue, which lacks the acid 'reserve' created by calcium carbonate, is particularly appropriate for use with silk and wool fibres that are sensitive to alkaline conditions.
Buffered tissue can create greater bulk when shaped for padding three-dimensional textiles, while in comparison, unbuffered acid-free tissue is softer and may be preferable for packing fragile textiles. Both forms of acid-free tissue can form sharp corners when crumpled. Hence, it is suggested that for fine laces or other delicate fabrics, such as silk net, that an alternative be selected. Bondina is a non-woven polyester material with a silky smooth surface is ideal for packing.
Lastly, the ability for acid-free tissue to absorb acid from materials with which it is in contact, also implies that migration can occur from storage containers. Therefore, it is equally important for acid-free boxes to be used for storing historic textiles.
