Use this magnesium-oxide buffering spray on acidic books or papers to neutralize them. It neither contains atmosphere damaging CFCs nor Freon. It is non-toxic and non-flammable. It is virtually odorless and very quick drying when used correctly. Bookkeeper, unlike some other deacidification sprays, does not clog. While it generally will not discolor paper, newsprint, ink, adhesive, or binding materials, you should always be sure to test a small area before all-over use. Bottles are sold by weight (not volume) and are offered in 150 gram (5.3 oz.) pump spray bottles and 900 gram (32 oz.) refill bottles. Long-time users may remember the 900 gram (32 oz.) bottles with trigger spray nozzles and may want to hold onto that old spray attachment and replace the standard cap. Coverage approximations are as follow: the 150 gram bottle will treat roughly 16.5 square feet of paper and the 900 gram refills treat 100 square feet. Spray a very light mist 6-8″ away from the item you are treating; make sure the spray is even and do not saturate the paper. There is no limit to the shelf life of these Bookkeeper products.