Validating transfer involves using stains on both the gel and membrane to visualize the transferred proteins. By examining these stained images, researchers can identify any errors in sample transfer early on, saving time and resources. Stain-free technology enhances this process by quickly capturing images of both the gel and membrane after transfer, allowing immediate confirmation of successful protein transfer. As another example, to validate tank transfer, the membrane should be stained with a reversible protein stain or using a pre-stained protein ladder. Ponceau S staining is commonly used as it binds to proteins and can be easily removed for subsequent antibody probing.