If investment castings are brittle and appear rough and discolored, there are probably issues in the foundry that should be addressed. There are a number of potential causes for these problems. First, the quality of the metal or alloys should be checked. They could be high in oxides and sulfides, particularly if they are recycled. The metal could be overheating or the dewaxing temperature could be too high. Other factors could also contribute to the problem. It is important to work with a foundry with the expertise, equipment and experience to prevent such issues.