The potassium iodide test papers use the potassium iodide starch reaction. The iodide is oxidized to iodine that then reacts with the starch to form the blue/purple color. The strips can be used directly in solution being tested. There is no need to wet them with acid that we know of. These strips will react once the contact the solution. Be aware that concentrated solutions may immediately “bleach out” the strip. This usually results in a telltale stripe at the water/dry strip interface.