1、從外觀上判斷

1. Judging from appearance

通過(guò)外觀上觀察和手感可初步判斷石膏粉質(zhì)量的優(yōu)劣。外觀上看，白度高的石膏粉細(xì)度目數(shù)高，質(zhì)量好，價(jià)格較高；而發(fā)灰發(fā)黑、里面有黑色雜質(zhì)的石膏粉質(zhì)量較差。用手的拇指和食指搓捻石膏粉，手感發(fā)沙粗糙的 石膏粉細(xì)度糙，質(zhì)量較差、價(jià)格較低；而手感細(xì)膩的石音 粉說(shuō)明細(xì)度細(xì)，質(zhì)量較好，價(jià)格也會(huì)較高。

By observing the appearance and feeling, the quality of gypsum powder can be preliminarily judged. Visually, gypsum powder with high whiteness has high fineness, good quality, and high price; Gypsum powder that turns gray and black, with black impurities inside, has poor quality. Rubbing and twisting gypsum powder with the thumb and index finger of the hand, the texture of the gypsum powder is coarse and sandy, with poor quality and low price; And the delicate texture of Shiyin powder indicates fine fineness, good quality, and higher price.

2、測(cè)定結(jié)晶水含量

2. Determination of crystal water content

石膏粉是一種結(jié)晶混合物，其中會(huì)含有生石膏、半水 石膏和無(wú)水石膏(過(guò)燒石膏）。在炒制過(guò)程中欠火夾生會(huì)出現(xiàn)生石膏，或者火大、炒制時(shí)間過(guò)長(zhǎng)造成過(guò)燒會(huì)出現(xiàn)無(wú)水石膏，這些都會(huì)影響石膏的凝結(jié)時(shí)間，影響生產(chǎn)的正常 使用。有時(shí)由于石膏粉放置時(shí)間過(guò)長(zhǎng)受潮，也會(huì)影響正常 使用。根據(jù)經(jīng)驗(yàn)和資料介紹，通過(guò)測(cè)定結(jié)晶水的含量，可判斷石膏粉質(zhì)量的好壞。

Gypsum powder is a crystalline mixture that contains raw gypsum, hemihydrate gypsum, and anhydrous gypsum (calcined gypsum). During the frying process, if there is insufficient heat, gypsum may appear, or if the heat is too high or the frying time is too long, anhydrous gypsum may appear, which can affect the setting time of gypsum and affect the normal use of production. Sometimes, prolonged exposure to moisture can also affect normal use of gypsum powder. Based on experience and information, the quality of gypsum powder can be determined by measuring the content of crystalline water.

3、測(cè)定石膏粉的凝結(jié)時(shí)間

3. Determining the setting time of gypsum powder

凝結(jié)時(shí)間包括初凝時(shí)間和終凝時(shí)間。石膏粉凝結(jié)時(shí)間的質(zhì)量標(biāo)準(zhǔn)是：在標(biāo)準(zhǔn)稠度下，一般初凝時(shí)間不小于 6min,終凝時(shí)間不大于25min。適宜的凝結(jié)時(shí)間是石膏粉 在生產(chǎn)中正常使用的先決和必要的條件。初凝時(shí)間過(guò)短或終凝時(shí)間過(guò)長(zhǎng)都不合適。

The setting time includes the initial setting time and the final setting time. The quality standards for the setting time of gypsum powder are: under standard consistency, the initial setting time is generally not less than 6 minutes, and the final setting time is not more than 25 minutes. The appropriate setting time is a prerequisite and necessary condition for the normal use of gypsum powder in production. Short initial setting time or long final setting time are not suitable.

4、測(cè)定試餅直徑

4. Measure the diameter of the test cake

按生產(chǎn)中石膏和水的比例，可通過(guò)觀察和測(cè)量試餅的直徑大小（流動(dòng)性）,來(lái)判斷石膏粉質(zhì)量的優(yōu)劣和決定 其在生產(chǎn)中能否使用。試餅直徑的大小與水量、膏水比例 以及石膏粉的質(zhì)量等因素有關(guān)。

According to the ratio of gypsum and water in production, the quality of gypsum powder can be judged and its suitability for use in production can be determined by observing and measuring the diameter (fluidity) of the test cake. The size of the trial cake diameter is related to factors such as water volume, gypsum water ratio, and the quality of gypsum powder.

5、生產(chǎn)中試注

5. Production trial injection

按生產(chǎn)中石膏和水的比例，確保所采用的器具、操作 人員、設(shè)備和工藝方法一致，選擇一個(gè)小型胎型母模進(jìn)行 生產(chǎn)模型的試注，與生產(chǎn)中正常使用的合格石膏粉的模型澆注過(guò)程進(jìn)行對(duì)比。若待測(cè)石裔粉凝結(jié)時(shí)間正常合理、 操作順利不注桶，則說(shuō)明該石膏粉是合格的石膏粉；若待 測(cè)石膏粉凝結(jié)時(shí)間非正常，凝結(jié)時(shí)間太短注桶，或者凝結(jié) 時(shí)間太長(zhǎng)甚至不凝固，這樣的石膏粉不合格，生產(chǎn)中絕對(duì)不能使用。

According to the ratio of gypsum and water in production, ensure that the instruments, operators, equipment, and process methods used are consistent. Select a small tire mold for trial injection of the production model, and compare it with the pouring process of qualified gypsum powder used normally in production. If the setting time of the tested stone powder is normal and reasonable, and the operation is smooth without pouring into the barrel, it indicates that the gypsum powder is qualified; If the setting time of the tested gypsum powder is abnormal, the setting time is too short to pour into the bucket, or the setting time is too long or even does not set, such gypsum powder is unqualified and cannot be used in production.