When using an oil immersed objective, only drip tar onto the specimen. After observation, it is necessary to carry out cleaning work in a timely manner. If not done in a timely manner, the cedar oil will stick to dust, and dust particles may wear the lens when wiping. The cedar oil will be exposed to the air for a long time, and it will also thicken and dry, making wiping difficult and detrimental to the instrument. Wipe carefully and gently. First, wipe the front end of the oil immersed objective with dry lens wiping paper once or twice, remove most of the oil, then wipe it twice with lens wiping paper moistened with xylene, and finally wipe it once with dry lens wiping paper. The cedar oil on the specimen slide can be wiped clean using the "pulling paper method" (that is, cover a small piece of wiping paper with cedar oil, then drop some xylene on the paper, and pull the paper out while it is wet. This is done three or four times in a row, and it will generally not damage the smear specimen without a cover glass). Mirror wiping paper should also be dust-proof. Generally, before use, cut each page into 8 small pieces and store them in a clean small culture dish, which is both economical and convenient to use.