Electrode selection is determined from the base metal chemistries and the percent of weld metal dilution. The electrode should produce a weld deposit with a small amount of ferrite (3-5 FN) needed to prevent cracking. In most cases the Arosta or Limarosta 309S electrode can be used. When the chemistries are not known, our Limarosta 312 electrode, which produces a high ferrite number, is commonly used.