In this reducing environment, the silicon in the clay reacts with wustite to form fayalite and, at around 2,190 °F (1,200 °C), the fayalite will become a liquid. This liquid acts as a flux, attracting impurities, and pulls out the impurities as it is squeezed from between the layers. This leaves a very pure surface which, in turn, helps facilitate the forge-welding process.[7][11][15] Due to the loss of impurities, slag, and iron in the form of sparks during the hammering, by the end of forging the steel may be reduced to as little as 1/10 of its initial weight.[4] This practice became popular due to the use of highly impure metals, stemming from the low temperature yielded in the smelting at that time and place.