This recipe goes back a couple of decades or more.  It is a simple way to
manufacture magnesium bicarbonate.  The water dissolves soluble acids out
of the paper.  The magnesium bicarbonate neutralizes acids, turning them
into water soluble salts, and leaves an alkaline buffer.
 
The recipe was presented as an affordable and accessible method for
deacidifying and alkalizing newspaper clippings.
 
In common with any method of deacidification, the newer the paper, the
greater the benefit (and the lower the danger of tearing wet paper...).
 
One element missing from the recipe as related below, is that after the
powdered tablet is put into the bottle (and the cap is screwed on tight)
shake the bottle well, let it set in the refrigerator for fifteen minutes
or so and repeat the shaking.  Then leave it in the refrigerator
overnight to allow the magnesium bicarbonate to form.  The bicarbonate is
unstable.  On exposure to the atmosphere the CO2 begins to go away; the
result is magnesium carbonate deposited in the paper, and that is the buffer.
 
Jack C. Thompson
Thompson Conservation Lab
Portland, OR
 
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On Tue, 17 Jan 1995, Sara P. Kelley wrote:
 
> One of our volunteers found a recipe in Yankee magazine for preserving
> newspaper clippings (de-acidification, I presume).  Has anyone heard
> of this?  Can you comment on its efficacy/dangers?  Thanks.
>
> "Dissolve a milk-of-magnesia tablet in 1 qt. club soda overnight.
> Pour into a pan large enough to hold the clippings (flattened).
> Let it soak for one hour.  Carefully remove and pat dry.  Do not move
> until completely dry."
>
> Sara Kelley
> LCHS Collections Manager
>
> --
> Lehigh County Historical Society
> PO Box 1548, Allentown, PA 18105
> (610) 435-4664
> [log in to unmask]
>