
Flowers of sulfur

Flowers of sulfur (British spelling flowers of sulphur) is a very fine, bright yellow sulfur powder that is produced by sublimation and deposition. It is known as ' by apothecaries and in older scientific works. Natural sulfur was also known as brimstone, hence the alternative name flowers of brimstone.
Production.
Flowers of sulfur were traditionally produced by subliming naturally occurring sulfur, known as "sulphur vivum". Impurities and moisture could cause acid residue in the product, so it was often washed, the result being known as "washed flowers of sulfur" (in Latin, "flores sulphuris loti").
Flowers of sulfur is commercially available and can be bought through chemical supply companies as well as major e-commerce websites.
Uses.
Historically, flowers of sulfur were extensively used medically to cure ailments, particularly skin diseases. In the early 20th century, "flowers of sulfur" was also widely used for agricultural purposes. It was specifically used in cultivating hop plants to combat and prevent fungal diseases caused by molds that can kill crops. Flowers of sulfur was also used to treat rosebushes similarly. These cases show that flowers of sulfur was one of the earliest fungicides and insecticides used agriculturally. More recent sources also show that flowers of sulfur acts a fungicide, insecticide, and fumigant, as well as an agent in the treatment of numerous skin diseases.
Flowers of Sulfur (FoS) Tests have also been used to test porosity of metallic finishes over silver, copper, and copper alloy substrates. The original FoS test method was standardized by ASTM through ASTM-B809 which was established in 1990. The current version of the standard is ASTM B809-95(2018). This test method is especially good at precipitating silver based failures such as those observed with network chip resistors. The Center for Advanced Life Cycle Engineering (CALCE) and the International Electronics Manufacturing Initiative (iNEMI) have both developed tests based on varying degrees to the ASTM standard.