What type of penetrant indication suggests a cold shut on a casting's surface?

The indication of a cold shut on a casting's surface is best represented by a dotted or smooth continuous line. A cold shut occurs when two streams of molten metal fail to fuse completely during the casting process, leaving a visible discontinuity on the surface. This discontinuity often presents as a line or seam that follows the contour of the casting, and it's typically smooth or dotted rather than jagged.

The other types of indications, such as a series of fine cracks, may suggest different issues like thermal stress or inadequate material flow, while a pronounced curve or a sharp point might indicate other forms of defects unrelated to cold shuts. Understanding the characteristics of different types of surface indications is crucial for accurate defect identification in casting processes.