Archival process
From Silvergrain Research
Contents |
Substrate Materials
Selecting substrate material that is stable is important. In terms of archival stability, the most preferred options are glass, polyethylene telephthalate (PET or PETE) and polyethylene naphthalate (PEN), the latter two often called polyester. These substrates are stable in any humidity level, so the longevity of the image is largely determined by that of the silver image.
The second best choices are modern cellulose triacetate films. This type of film is commonly used due to superior cost-performance and better curling property than PET. However, this type of film base degrades over time. It is essential to ensure to keep them in (1) fresh circulating air, not in a closed container, and (2) low humidity environment.
For print material, the choice between fiber base paper and resin coated paper had been controversial for some time. However, with current technology, this author believes that they are equally suitable for important work, as long as they are processed and stored properly.
More details on film, dry plate and photographic paper.
Archival Processing
Coping with suboptimal storage conditions
In b&w processing, the most effective step one can incorporate to ensure maximum image permanence is to treat the print in sulfiding toners such as Poly-Toner, Kodak Brown Toner. Untoned prints are "archival" as long as it is properly processed and stored in ideal condition. The emphasis is on the ideal storage condition, which would require strict control of air quality, temperature and humidity. The problem is that, in today's office and home environment, such an ideal storage condition is impossible to obtain. Even clean room air contains significant amount of oxidants (peroxide, nitrogen oxides, etc.) that will attack silver image over time.
Toning is a very effective way to give additional protection to the image, the protection that is useful in such suboptimal storage condition. Ag Guard is an alternative option.
Removal of processing chemicals
The material musth be adequately washed, preferrably with the use of washing aid. The residual thiosulfate level must meet archival standard.
Storage Conditions
B&W materials are considerably more durable than most color materials. However, one most important factor in storage condition for b&w material is humidity. A relative humidity of 30 to 40% is ideal for storage. Refer to Conservation for more details.
