Candied Orange Peel

I've used this recipe to make candied orange peels which doesn't call for removing the pith:
http://www.foodnetwork.com/recipes/food-network-kitchens/candied-orange-recipe/index.html
I definitely like the 3 time blanch the best (and have done 4 blanches when candying lemon peels). There is very little bitterness, and the texture is great. Even if there is wax on the oranges the blanching step should rid them of it.

I scrape the bitter pith always so most is off. add 1/4 tsp. cream of tartar and in soaking water. To the sugar syrup Add 2tbs. of corn syrup. After rolled in sugar and dried a bit, sometime I dip in chocolate.

My first thought was the same as HalfPint's -- pith could easily explain the bitterness. So might the type of oranges (Seville for instance). I wouldn't worry about any wax or other contaminants though. If there was any, it would have come off in the first boiling.

When I candy citrus peel, I let it sit in the syrup overnight. That might help.

I'm curious about boiling the syrup to the softball stage. I've never done that and, frankly, don't understand the purpose. Might explain the toughness.

Were they organic oranges? A lot of supermarket fruit tends to be coated in wax to keep them from drying out.

If not, maybe you have to much pith still attached?