To Get Yellow, use: yellow onion skins, turmeric, chamomile, sage, celery leaves.
To Get Orange, use: any yellow dye plus beet juice.
To Get Red, use: beets, safflower seeds, paprika, rose hips tea.
To Get Blue, use: blueberries, grape juice concentrate, red cabbage.
To Get Brown, use: black tea, white oak, juniper berry, coffee, barberry.
To Get Violet, use: blackberry, grapes, violets.
To Get Green, use: alfalfa, spinach, kale, parsley, carrot tops, beet tops. OR dip yellow egg in blue dye.
Hard-cook eggs with 1 tablespoon vinegar in water. Place dying materials in non-aluminum pans, cover with water and boil 5 minutes to extract the color or until darker than you like. Grapes may take as long as an hour. Use enough material to make at least 1 cup of dye. Crush ingredients as they boil to extract as much color as possible. Strain the dye. Most dyes should be used hot.
Temperature of the egg does not matter. Leave egg in dye until it reaches the desired color. Some dyes will take longer than others to color the eggs. Remove and let dry. Experiment with mixing dyes to get different colors. This would make a great rainy day activity for the kids with adult supervision.