Richard D. Smith      Wei T’o Associates, Inc      October 15, 1998


The most important step that an individual can take to reduce the rate at which his or her records are aging is to neutralize papers with are acidic and impregnate them with an alkaline buffering agent to prevent reacidification. Many methods have been developed to deacidify paper including treatments with aqueous and nonaqueous solutions as well as alkaline gases.

Aqueous (water-based) deacidification solutions are good choices when the cost of labor is less important than the cost of chemicals and the article being treated will not be harmed by wetting it with water.

The treatment of paper with the following solution of magnesium bicarbonate in club soda was developed at The University of Chicago by R. D. Smith about 1965. It will deacidify acidic papers, deposit a substantial quantity of Milk of Magnesia buffering agent, and tend to prevent the development of brown spots (foxing).



a) One quart of salt free club soda (available in supermarkets, grocery stores, etc.)
b) Magnesium hydroxide, technical or reagent grade, (available locally from chemical or laboratory supply houses and by mail order from TALAS, 568 Broadway, New York, NY 10012). Magnesium carbonate or oxide, though less soluble, may be substituted.
c) A plastic, aluminum, enameled, glass, or stainless steel pan measuring about 10″ x 12″ and 2 1/2″ deep (available in hardware stores).
d) White blotting paper (available in stationery stores).
e) Paper towels (available in supermarkets or grocery stores).


Wet two teaspoonful of magnesium hydroxide with one or two ounces of club soda. Mix and pulverize any hard particles with the back of the spoon. Pour or spoon the slurry back into the quart of club soda. Replace the bottle cape and shake the closed bottle gently to thoroughly disperse the slurry. After this initial shaking, replace the bottle in the refrigerator and keep it there because a stronger solution is produced with cold club soda. After ten, twenty and thirty minutes, take out the bottle and shake it gently to redisperse the undissolved white powder. Continue shaking every ten minutes until essentially all of the magnesium hydroxide is dissolved. Then allow the bottle to sit quietly in the refrigerator for thirty minutes or until the undissolved powder settles to the bottom of the bottle.


Pour the clear solution of magnesium bicarbonate in club soda carefully into the pan, previously cooled in the refrigerator. Place the papers to be treated in the solution one by one. Press each sheet of paper gently into the solution to insure it is thoroughly immersed before the next sheet is added. Soak up to twenty-five 8 1/2″ by 11″ sheets of paper in this solution for a minimum of twenty to thirty minutes. Soaking for one or two hours normally is not harmful. Raise and lower the sheets three to four times to facilitate contact with fresh solution. Weak and embrittled sheets can be protected by handling them individually on sheets of strong paper or plastic, or on an aluminum or plastic screen. Remove the sheets from the pan after treatment and allow the excess solution to drain away. Discard the solution remaining in the pan. Dry the sheets in the air until the paper is dry-damp. Then place the sheets of paper one by one between sheets of blotting paper. Continue the drying procedure under moderate pressure (several heavy books) until the treated sheets are dry. Very wet papers may require one or more changes of blotters to be sure the treated sheets dry flat.


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