When used as directed, Chem-i-Weld will permanently repair existing cracks, flaws and porosity in automotive cylinder heads, blocks and other cooling system castings. It works by hardening on exposure to air in a confined space and will continue to harden in the leak area back to the main body of water.
Chem-i-Weld contains a 'meal' which acts as a filler to restrict the water flow through large leaks (much the same as the bushremedy of sealing radiator leaks with pepper) so that the Chem-i-Weld has a chance to reduce the liquid flow and harden. Chem-i-Weld's red colour comes from ferric oxide, a powder which acts as a much finer filler, hence the name CHEMIcal WELDing COMPOUND.
