Analyists in cooperation with the magnesium health institute performed tests and this is their conclusion:
Using flakes as a basis for making high concentrated “magnesium oil” greater then 5% is not recommended. Flakes are produced by an evaporating process in which a raw magnesium chloride brine from the source is heated up to approximately 160 Degrees Celcius and the water is evaporated till a concentration of 47% of magnesium chloride is reached. This concentration represents the right proportions to get magnesium chloride hexahydrate [ MgCl2.6(H2O) ] which gives a stable flake after crystallization on a cooling-belt.
Due to the heating for evaporation a very small amount of MgCl2 will decompose to MgOHCl (magnesium hydroxide chloride), MgCO3 (magnesium carbonate) and some HCl (hydrochloric acid) in the vapor stream. This process is also responsible for the white haze that can be seen when dissolving the flakes. These products are not directly hazardous but are by products of the necessary production step to get flakes. For applications up to 5%, such as bathing, the flakes are the perfect option.
For topical applications with higher concentrations, we recommend the pure natural magnesium oil straight from the source without any heat treatment. This magnesium oil is especially selected for this application and is secured by the Zechstein batch protocol.