This section is from the book "The Gardener's Monthly And Horticulturist V23", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
In making a wash to shade greenhouses, slack good lime with water, using only water enough to make a paste, and thin the paste with skim milk, and it will last much longer than if reduced with water.
If you warm sour milk or lobered milk just so it separates the whey from the curd, pour away the whey and use the curd to thin the lime and it will stand longer still, so that if the curd is well separated from whey, it will last all summer.
The curd will dissolve in the lime, and thin it more than you would suppose until you tried it. If too thick thin with milk or water.