Boil black plaster. A drop of water forms a pearl. What is the state of oil droplets falling into water?

Refining is the key. Pay attention to whether to refine oil from the following three aspects. (1) Look at the lampblack: blue smoke comes out after the oil is boiled, but the smoke is weak. The blue smoke turns from light to thick, and continues to boil after turning to ash, and then the smoke turns white (the process is about 1-2min), and refining is almost complete. (2) Look at the oil flower: Generally, when the oil begins to boil, the oil flower will be around the pot wall, but it is similar when the oil flower begins to gather in the center of the pot. (3) Dropping water into beads: a small amount of medicinal oil is dropped into water, and the oil droplets are dispersed after gathering into beads. The above two methods, 1 and 2, are difficult to distinguish, so a general understanding is enough. Let's talk about dripping into beads first, which is a common method of traditional plasters. The refining process takes a long time, at least 30 minutes to 1 hour, or even longer. Prepare a basin of cold water in advance. You can cook for about half an hour, take the pot out of the fire, dip the medicinal oil in the basin with a stirring rod, and drop 1-2 drops. The medicinal oil drops into water, and gravity makes the oil drops disperse first, and then the oil drops aggregate into beads, indicating that the oil refining is completed. If the oil droplets are dispersed and not condensed, it means that the temperature is still poor and tempering is needed. Then try it every 2-3 minutes. It may be troublesome for the first time, but when you operate it yourself a few times and become proficient, you will have a good idea. The old tender experiment is to check whether the plaster is ripe.

way

1. After the plaster is boiled into a black and bright plaster, leave the fire first. You can take a drop of plaster and drop it on the plaster paper to see the adhesion of plaster.

2. You can also put a little plaster in the water, cool it a little, and pull out the filaments by hand to indicate completion. If it is soft and weak, sticky and weak drawing, it means it is too tender and will continue to boil; If the drawing is uneven in thickness or fragile, it means that it has gone too far.

3. Dropping water into beads: a small amount of plaster is dropped into cold water, and the beads are not scattered and the paste is black and bright, indicating that it has been completed. Gray means it is too tender and needs to be continued.

Too hard: generally, there is a large amount of lead and it takes a long time to boil.

Too soft: generally, there is less lead and the boiling time is short.

The above commonly used 1 and 2 are used for detection, and it is enough to know method 3.