I guess using liquid draino isn’t the safest nor environmentally sound choice and for bathroom sinks, you might just be able to unclog your drains/pipes simply by cleaning the U-pipe attachment. Not a bad solution plus it will save you some money buying that toxic, chemical stuff or calling your local plumber.
The steps of this instructable show you how to remove biological mysteries from your sink’s drainage without using caustic chemicals that cost money, are bad to breathe, less fun and whose success as an unclogging strategy has a lot of uncertainty.
My bathroom sink is simple enough that the pipes and pop-up assembly do not require any special tools to take apart and put together. The only tool I employed besides my hands was an old tooth brush.
Btw, my friend is a plumber in SF bay area, call him and refer Max from Zedomax.com referred you for deep discounts!