To inexpensively cut the amount of light without cutting it out completely use a trick from the greenhouse owners. One way is to mix whitewash or hydrated lime with water, then apply the mixture with a roller or sprayer over glass surfaces. However, lime solutions are not recommended for aluminum-framed skylights. Another inexpensive solution uses one gallon of white latex paint and eight gallons of water. Spray, brush or roll the thinned mixture on. More coats increases opaqeness. The material can be stripped fairly easily.