Covering a bright color with an opposite shade will require multiple coats of new paint. If it was reversed where you where painting the green over yellow then you would need a primer as the yellow would actually bleed through the green. The Reason Why Everyone Love Painting Over Light Yellow Walls Painting Over Light Yellow Walls Yellow Painted Walls Bedroom Paint Colors Light Yellow Walls This way you will only need 1 to 2 coats of your actual color paint. Painting over light colors . With acrylic you have the option of doing both. The choice really comes down to what makes you and your budget comfortable. Ive painted over greens blues and reds with light colors whites antique white countless times and 2 coats of a quality paint has always covered. Both as the paint dries quickly and you can paint over things. Dark paint colors are notorious for creeping through lighter colors but you can prevent this by preparing the area properly before you paint. Oil-based paint needs...