Then we decided to try the leftover coffee on brown eggs - a light brown one from Gylfie and a darker one from Twilight. I wrapped rubber bands around them to create a design (tip - it's easier to tie a knot in the rubber band before you slip it onto the egg). Those went to soak in the refrigerator until tomorrow morning.
Next Miss Joy wanted to try a yellow or orange dye, so I sprinkled some curry powder into a cup of warm water and added a glug of apple cider vinegar. Did the rubber band thing and again put 2 eggs to soak in it overnight in the fridge (all the eggs went in the fridge except for the one Miss Joy ate as a mid-morning snack).
Here are the results:
The coffee stained the light brown egg very dark, but the darker brown egg didn't really end up any darker than the light one did. The color didn't take very evenly, but could make for an interesting tea-stained effect. The stripes were visible but a bit boring in all the same color (and I didn't have time to dip them again, maybe in beet juice for a pink tone on the center one would have been nice).
The curry powder did stain the light brown egg but I wouldn't call it yellow, just muddy, and it didn't take evenly. For some reason as it dried it seemed to "shed" the color though it looked even when I took it out of the bath. The dark brown egg ended up a little bit more orange than yellow and the pattern was barely visible. Maybe it's because of the coriander and other spices in with the turmeric, or maybe a white-shelled egg would have ended up bright yellow but we were a bit disappointed with these.
All in all, the ones that we think turned out the best were the marbled ones we did with blueberry juice on the blue-green eggs. We're going to have to figure out some other dyes to try on the brown eggs next year.