This is an old-school trick that was taught to me by my mother-in-law. I can't believe I used to spend $4-$5 on products like, Drano Foaming Pipe Snake. This SIMPLE technique takes only two ingredients.
Here is all you need:
1/2 cup of baking soda
1 cup of vinegar
1 qt (or so) or boiling water
Step #1: Pour the baking soda into the sink drain. You want to try to get as much into the actual drain as possible. The bathroom sink I have at home won't let me remove the plug completely so I do my best to pour the baking soda right over it.
Step #2: Pour the Vinegar over the baking soda. (It's pretty much the same mixture you use when making a volcano for a school science project).
Step #3: If your drain does not have a stopper, you want to quickly use a washcloth to plug the drain, keeping the foaming action inside the pipe. If your sink is like mine, you will want to give the mixture a good stir to dissolve all of the baking soda and make sure it all gets down the drain.
Give it about 30 minutes or so to work on the clog. Then pour the boiling water down the drain to flush it out. The great thing is that the baking soda and the vinegar only cost around $3 together. They also serve many other purposes and are items that most people always have on hand. Try this out and you will NEVER buy Drano from the store again!