Protecting handmade electronics from accidental water spillings
When there is current under water, there is electroylsis, and that causes corrosion. YouTuber GreatScott (highly recommended) has 2 videos:


https://www.youtube.com/watch?v=pGLUsQozT94
https://www.youtube.com/watch?v=h8ycmroFQSs


They are basically the answer to your question.