Thanks Hitchmss for your comprehensive answer! I think this is what I love about clay, people use what they have at hand and make something out of it, beautiful or functional, or both!! Maybe I am in a little bit of uncharted waters,so best way to find out is to try. Yes very keen on being safe, I like the idea of seaweed (I can use the bits I don’t eat!!) and other natural materials, maybe some salts. Like the idea of ferrous chloride and note the potential harmful effects of this substance. Crawling, pinholing etc are all good, happy to be on the edge of it working/not working. Below is an image of a chawan that to me is beautiful, I doubt I can replicate, but will try a few things and see!
Will take me some time to get my head around all the clays/glazes etc, but it is a journey not looking for a destination!