Old School Tech has released an article about extracting raw potash from wood ashes. Future projects will refine and use this raw product for interesting things. Not only does this project make a great homeschool chemistry lesson, it also sets the stage for some chemical processes of interest to self-sufficiency enthusiasts.
As mentioned in that article, we have been using the same roll of Hydrion pH paper for decades. At about $10 per roll, given how useful this paper is for a variety of processes, it makes sense to have a roll or two tucked away just in case.