What type of penetrant can be described as “water-washable”?

The correct answer is that penetrants that dissolve in water can be described as "water-washable." This term usually refers to a specific category of penetrants used in non-destructive testing. These penetrants are formulated to be easily removed from the surface with water, allowing for a quicker and more efficient cleaning process.

By employing water-soluble penetrants, technicians can effectively inspect materials for defects without the need for harsh solvents or chemicals. This not only makes the cleaning process simpler but also reduces environmental impact and operator exposure to potentially harmful substances.

In contrast, other types of penetrants listed require different removal methods, such as solvents, manual scraping, or heating. These methods can add to the complexity of the inspection process and may increase the time it takes to complete the task, making water-washable penetrants advantageous for their ease of use.