The most important course for the deterioration of artworks, books and documents made of paper are acid damages. For reasons of conservation and high-quality framings it is recommended to use acid-free carrier materials as well as passe-partouts. This is a matter of fact for Willen! Like this the ageing process can be stopped in the case of existing embrittlements or it can be decelerated. The pH value of the paperboard materials is regarded as alkaline, i.e. acid-free from 7.5 – 9.5. Values from 7.0 – 7.5 are regarded as normal which, however, is not sufficient for absolute conservation.
A short explanation of some terms:
Conservatory framing of pictures:
Preserving framing of pictures using ageing resistant and buffered paperboard types with active protection of the artwork
Ageing resistant / archivable:
Paper and paperboard which last a lifetime when being properly stored.
Paper:
Flat fibrous fleece with a thickness of approx. 0.05 - 0.2 mm and / or a surface weight of 10 - 150 g/m2.
Paperboard:
Thicker fibrous fleece of 0.2 - 0.6 mm and / or a surface weight of 150 - 400 g/m2. Stronger qualities are manufactured in multi-layer technology by means of laminating.
Sizing:
Sizing is a certain water resistance of paper and paperboard which makes it writeable.
Alum:
Aluminium sulphate; with water it becomes sulphuric acid
Groundwood:
Mechanically treated wood fibre. Contains resin and lignin.
Pulp:
Chemically treated wood fibre. Mainly freed from resin and lignin substances due to additional bleaching. Therefore high ageing resistance.
pH value:
For the ageing resistance of paper and paperboard a pH value of 7.5 – 9.5 (=alkaline) is required. Under 7.0 = acidic. 7.0 – 7.5 is neutral to slightly alkaline. However, is not sufficient for the active, conservation protection
English 
Deutsch 