Sodium hydroxide, commonly known as lye, is a white solid. This characteristic color is due to the compound's crystalline structure and the absence of any colored impurities. The white color is consistent across various sources and is well-documented in scientific literature. For instance, the CRC Handbook of Chemistry and Physics states that sodium hydroxide is a white, crystalline solid (CRC Handbook of Chemistry and Physics, 97th Edition, 2016-2017). The purity of the compound also contributes to its color, as impurities can alter the appearance. In industrial applications, sodium hydroxide is typically produced to a high degree of purity, ensuring its white color.