I am coordinating the translating of the tutorial and I do not understand what caustic effect means or even does. The only meaning I know off is from caustic soda, which is used to remove paint. Searching on Google suggests encaustic, which means painting with wax. So my question: where does this term come from?
Hello and welcome to the forum
Google searches often give only the most common or popular results.
Wikipedia is often better for specialist or technical terms:
" Concentration of light, especially sunlight, can burn. The word caustic, in fact, comes from the Greek καυστός, burnt, via the Latin causticus, burning."