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My kids hate the smell of vinegar.  One option is to skip the dye entirely, and just decorate eggs with ribbon (as in this photo), markers, paint, string, decoupage, or whatever...

but there's something about dyeing eggs that takes me back to childhood memories of sitting on tall stools around the kitchen counter, dunking eggs with those flimsy metal dippers. 

So I just have to dye eggs.

(If you want to color eggs using natural dyes, there's a link at the bottom to a previous post.)

Why, though, do all instructions seem to call for using vinegar?  Some of the newer kits have the vinegar built in to the tablets, but it's still there.  What does it do? 

I ran some searches, did some experimenting, and here's what I've learned:

Several people online said it's to make the dye darker.  Someone else said you could use salt instead.  So I started looking into the science of why.

Vinegar is acidic.  Egg shells are mostly calcium carbonate, which is alkaline.  Put them together, and they react, dissolving some of the egg shell.  I put a hardboiled egg into straight vinegar and left it overnight.  In the morning, only a thin layer of shell remained, and by late afternoon, there was no more shell; only the flexible inner membrane was left.

Adding vinegar to the dye bath helps etch the shell, roughening the surface (increasing surface area) and thus allowing it to receive more dye.

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If that was the case, then, shouldn't other acidic ingredients work?  What if I don't have vinegar on hand?  And would it work as well to just add vinegar to the water the eggs are hardboiled in, and not need vinegar in the dye bath?   Here's how the experiments turned out:

The deepest, most even color was from vinegar in the dye, followed closely by the eggs boiled in vinegar water.  Lemon juice did pretty well but yielded more color marbling.  The dye using plain water (no acid) gave me a much paler and less evenly colored egg.

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The salt water dye (using 2 tsp. salt in 1 cup water, producing the egg on the left) was slightly better than plain water, but not much.  Salt is a mordant, which means it physically or chemically helps the dye bind to the surface, but it did not work well here. 

So I'll go back to vinegar when I want deeply colored eggs.  Here are the amounts I used:

1 cup water
10 drops liquid food color (you can use less)
1 Tbsp. vinegar (or lemon juice)

Or, to restrict the smell of vinegar to a one-time boil, add 1/4 c. vinegar in 1 quart of water, hardboil as usual.  I'll tell my kids they can either stay inside where the smell is, or go outside and pull weeds...

Happy coloring!

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Are you ready for some kitchen fun now?
 


Comments

04/09/2014 05:35

Thank you for posting the results of your experiment! I'm going to dye eggs today and this is very helpful.

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