I fell in love with a store bought gunk remover "goo gone" years ago when I started up cycling glass and plastic, but I found the ingredients to be less than desirable. After searching the interwebs for a recipe that used citrus essential oils, I couldn't find one! So I decided to wing it, and the resulting product works fantastically!
Just three simple ingredients:
2 tbsp coconut oil
1 tbsp baking soda
5-10 drops lemon or orange essential oil
Whisk the coconut oil in a small dish until smooth. Add remaining ingredients, stir well.
That's it! Now you're ready to use your natural gunk remover! I grabbed a
spaghetti sauce jar out of my cabinet and got to work. Just rub a tiny
bit directly on the gunk. Once you've rubbed it in a little, wipe with a
cloth or paper towel. You may have to repeat this process a few times,
but I didn't find it necessary for this jar. Then just rinse and dry,
and your jar is clean and ready to re-purpose!
I've seen people mention that the baking soda might be harsh on plastic, so I plan to make a baking soda free version if I come across a plastic container I want to re-use