LEAF CASTING ON THE SUCTION TABLE
3 VACUUM TABLE
WHEN MARILYN WEIDNER introduced the vacuum suction table at the 1974 AIC meeting, it was difficult to imagine all of its possible applications. Since that time, it has become such an important tool in most laboratories that paper conservators often wonder how they could practice without it. Many people have built, modified, analyzed and used suction tables over the last eight years. Inexpensive home-made models can serve quite well, as can the more expensive and elaborate commercially available models. Important factors to consider for both general use of the vacuum table and leaf casting are:
- Openness of surface. Thick masonry tops tend to restrict air flow and become clogged.
- Flatness of surface. Any material other than very fine screen or some perforated metals will impose their texture on the paper or blotter in contact with it.
- Suction. The pump/fan arrangement should have the capability of lifting a column of water at least 80 inches high.
- Air flow. This will vary depending on the size of the table. Generally 20 cubic feet per minute (CFM) per square foot of table surface is a reasonable guideline. A table 2′ � 3′ (6 � 20 CFM) would perform quite well for most purposes with a suction system that could deliver 120 CFM.