What are the general principles of gel staining?

To make proteins visible, a specific dye or chemical reaction is applied to the proteins in the gel. This requires several main steps described below.

1. Water Wash: Rinse the gel with water to remove the electrophoresis buffers from the gel matrix. 
2. Acid or Alcohol Wash: Use an acid or alcohol solution to condition or fix the gel, which helps to prevent the diffusion of protein bands out of the gel. 
3. Staining Treatment: Apply a staining reagent to allow the dye or chemical to penetrate the gel and bind to or react with the proteins. 
4. Destaining: Remove excess dye from the gel background to enhance the visibility of the protein bands.

These steps are carried out in liquid, with the gel immersed in various reagents. After electrophoresis, proteins remain bound to the anionic detergent (SDS), and the gel is saturated with the running buffer.