Yet Another Cleaning Question. Like You Haven't Had Enough.

I have tried everything! Water, oil, sodium bicarbonate, hydrogen peroxide, isopropanol, wd40, am I missing any? I've even tried some unorthodox methods such as skin moisturizer and fabric softener. Some of these have had great results but there are still some coins that refuse to clean. There are 2 methods I am thinking of trying next and would like to know if anyone has any experience with these before I try.

Sodium hydroxide- also called lye. I have heard of some people using this. I know the dangers I just need to know if this will remove the patina if left to soak too long.

Hydrochloric acid- I have heard of people using this to clean rock or mineral samples. Same idea except that they have been buried significantly longer. I know it won't dissolve copper without an oxidizing agent but it may dissolve other lesser metals alloyed with the copper. It will probably dissolve the patina as it's a form of oxidation. I'm wondering though, if a quick dip followed by neutralizing the acid would be enough to loosen the encrustations before any damage occurs.

Please let me know if you have had any actual experience with either of these methods. Thanks