This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
To 1 qt. of flour add about 2 oz. of 90-per-cent ammonia and enough lukewarm water to make a dough. Wipe the paper with this preparation while turning and kneading it as in making dough. This will take up the dirt and a clean side is always presented to the paper. - Contributed by F. C. Myer, Tacoma, Wash.