Use of hydrochloric or sulfuric acid to dissolve bolt?

I have a bolt rusted onto the bottom of my bathroom sink faucet. I have tried to loosen it with a plumbing tool and lots of WD40 but it won't budge. I'm wondering if I paint hydrochloric or sulfuric acid onto the bolt, could this help loosen it? I read an answer about these acids to be careful mixing them with water so I'm wondering if I can thicken the acids by making a paste of cornstarch and water. I'll heat the cornstarch and water mixture till it's real thic, let cool, and then add the acid after. I'll then keep painting it on the bolt till the rust and metal dissolves enough to loosen it. I am putting on a new faucet so I don't care if any of the metal is ruined. I just need to get it apart without breaking my pedastal sink. Will these acids harm the porcelain of the sink? If I can mix my cornstarch solution and acid, should I follow the guideline of one answer I read to poor acid in slowly while stirring since water can make the mixture hot?