Volume 14, Number 6
Oct 1990

Paper Washing Machines

An English-language description of the paper (and book) washing machine sold by Ingenieurbüro Klaus Voss has been furnished on request. The picture, not reproduced here, shows something that looks like a leafcaster. It must be the current version of Karl Trobas's Book-Washing Machine, described on p. 68 of the July 1985 issue of this Newsletter. Like the Trobas machine, this one seems to be marketed to people without knowledge of conservation. Here is the description:

"The new Paper Washing Machine, Austrian Type, can perform all aqueous treatment of old papers, documents, autograph letters and books, in particular the washing and cleaning of dirty papers, deacidification, bleaching and disinfection of great numbers of sheets of paper or books.

"The cleaning of single documents is very often very time-consuming but it can be necessary for very valuable autograph letters or books. Deacidification of papers which suffer from "ink-rot" is a specially important task and takes a lot of time. In one cycle the machine will clean up to 600 sheets 200 x 300 mm completely automatically. A special additive puts a stop to the rotting effect of old ink which in time tends to destroy paper. For deacidification, usually normal tap water will be used for washing out iron ions and S0₄ radicals. The water should be at normal room temperature; no heating is necessary. A digital thermometer on the machine will show the temperature. The treatment should last 4-6 hours because usually at least 3 hours are needed for the soaking of the paper. For cleaning and washing a special paper cleaning solvent (Kr 85 or another paper cleaning liquid) is added. The duration of this treatment depends an how dirty the papers are.

"The Machine consists of a plastic tub 865 x 615 mm and box 200 mm deep in a lacquered steel plate with cover. Four feeds/drains serve to fill the tub with water and empty it after the cleaning process. You can fill the machine with 600 sheets of paper or up to 4,000 bookparts for one cleaning cycle. The papers lie between plastic screens (75pieces): one screen, one quire of papers, one screen, and so on. On the top and bottom there are strong plastic lattices."After the machine is filled with papers it is filled with water from the hose and the cover is closed. The operator chooses the intervals of waterpumping and stops, i.e., 20 sec., and switches on the pump. This will circulate the water at intervals of 20 sec. With interval pumping the packet of papers/screens will swing. This is necessary for good cleaning and deacidification.... The prototype of this machine has been in use at the Steiermärkisches Landesarchiv in Graz, Austria, since 1984 and has stood the test of time."

Information is available from: Ingenieurbüro Klaus Voss, Schlossplatz 1, D-8762 Amorbach.

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Another paper washing machine, for which a dryer is available, is described on p. 258 of the October 1988 Restauro.

Based upon a somewhat different principle is the paper washing machine developed by Dag-Ernst Petersen in Wolfenbüttel. This machine allows better function monitoring, especially of the wash cycle and of buffer action. The sheets to be cleaned are laid between screens which are rolled up onto a spool. The spool is then inserted upright into the wash cylinder.

The washing fluid flows from the top of the cylinder downwards, passing through the screen layers and thus removing dirt particles on the individual layers of paper. The vertical direction of flow assures even wetting of the sheets. The temperature of the washing fluid can be varied.

It is possible to control the amount of cleaning fluid applied with an electric pump. The soaking and washing cycle times are adjustable. All operations are indicated by photodiodes.

The wash cycle consists of filling the cylinder, repeated soaking and washing, and draining. The cycle can be interrupted at any point and begun again. On the back of the unit are to be found the connections for hot and cold water, demineralized water, and deacidifying or buffering solution.

Upon request an automatic cycle program can be installed.

The cleaning process is regulated according to the amount of dirt in the water. Since the electrical conductivity of water changes with the amount of dirt in it, a conductance meter monitors the water conductivity through a sensor in the cylinder.

Automatic paper dryer. This dryer complements the paper washer and is similarly constructed.

The main component of the dryer is a vertical cylinder into which the spool containing the cleaned paper is inserted. Warm, dry air is forced from the bottom of the cylinder upwards and the paper is gently and evenly dried.

Air temperature and fan speed are infinitely variable.

The intake and exhaust air temperatures are continually monitored. Drying is terminated when both temperatures are the same.

For further information; Maschinen- und Apparatebau Georg Hoffmam, Hauerstr. 2-4, D-3325 Lengede, West Germany