What is etching and what is the function of etching? What is a darkroom and what is its function? ⊙? Thank you! *^_^*

Etching is a technology to remove materials by chemical reaction or physical impact. Etching techniques can be divided into wet etching and dry etching.

General etching, also called photochemical etching, refers to removing the protective film of the area to be etched after plate making, exposure and development, and contacting with chemical solution during etching to achieve the effect of dissolving corrosion, forming concave-convex or hollow molding. It can be used to manufacture printed concave-convex plates such as copper plates and zinc plates at the earliest, and is also widely used to reduce the weight of dashboards, nameplates and thin workpieces that are difficult to process by traditional processing methods. Through the continuous improvement and development of process equipment, it can also be used for the processing of precision etching products of electronic sheet parts in aviation, machinery, chemical industry and other industries, especially in semiconductor manufacturing, etching is an indispensable technology.

The so-called darkroom technology is to achieve special effects through some special skills when developing photos. Specifically, there are many skills, and we only practiced a small part in the photography class. After all, now that photos are digitized, PS is obviously much better than developer and fixer. For example, if the negative exposure is too insufficient, the exposure time of photographic paper will be slightly shorter, and the immersion time of developer will be shorter, so as to avoid being "too raw" and "too ripe" because of the negative, and vice versa. If there are problems in some parts, you can use a hood or finger to slightly block the light of the exposure machine and make adjustments. As for some special effects, you can use the bottom superposition technology, that is, several films are superimposed and exposed together, which can produce very strange effects. This is the origin of the concept of "bottom stack" in PS. Of course, it depends on whether you are positive or negative. The bottom superposition effect of positive film and negative film is completely different. As for the effect of exaggeration, in theory, if shooting is ideal, it can be achieved by folding the bottom to cover it, but-ideally, everyone who has studied physics in high school knows what these four words mean. Generally speaking, implementation is possible (though small), but the effect is not guaranteed. After all, compared with modern digital image processing technology, darkroom technology is far from effective.