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 keep paint from drying out in an open can it is necessary to exclude the air from the oil. This can be done by procuring an air-tight paper sack, which is tested by blowing into it. Set the can into the sack and tie it tightly with a cord. Mixed paint will be kept in a working state in this manner.,