Simplify the following text for a Grade 11 native English-speaking person.
Original: In theory , mixing equal amounts of all three pigments should produce gray , resulting in black when all three are applied in sufficient density , but in practice they tend to produce muddy brown colors .
Simplified: In theory , mixing equal amounts of all three pigments should produce shades of gray , resulting in black when all three are fully saturated , but in practice they tend to produce muddy brown colors .