Children enjoy designing a special egg with their name on it using this technique. Using a crayon, simply draw a design onto the chicken eggs and then dye as you would any other Easter egg. The crayon design will be accentuated by the dye.
Please be aware that young children will sometimes not understand that someone else may find "their" egg, so you should make something special of it - like if you find an egg with your name on it, you get a wish and if someone else finds your special egg, you will be friends for life.
Fill the clean blown shell with sand and plug the hole with melted wax. Draw the design of your choice on the egg.
Make sure you go over the design several times, put as thick a layer of crayon on the egg as you can.
Put the egg in the vinegar.
After 3 hours, remove the egg and scrub the un-colored areas with a toothbrush to remove some of the residue. Be careful not to go over the crayon marks. If you think you have removed some of the marks, pat the egg dry with a paper towel and mark with the crayon again. Put the egg back in the vinegar for another hour. If you are satisfied with the way the egg looks, remove it, if not, put it back in for another hour or two.
The vinegar will etch away all exposed shell. If you are working with a bumpy emu eggshell, the pits that are untouched by the crayon will be eaten away also. This makes an interesting textured effect.
When enough shell has been eaten away by the vinegar, scrub the egg with a soft toothbrush, being careful n not to remove the crayon markings.
As a very simple example, this emu egg was marked with a light green crayon before putting it in the vinegar. The finished egg took 5 hours to complete.
This egg was decorated with a lizard, notice how the pits were etched out leaving white areas in the body of the design.
Vinegar etching can be done with any ratite egg (emu, ostrich or rhea), or other bird egg. If you try this with a chicken egg, it would be better to purchase directly from a farm with free ranging chickens. The eggs in the grocery store tend to be too thin for this technique. On smaller eggs, you will not have to leave the eggs in the vinegar for as long, check them often.