How can you test whether the scanner glass is adequately clean and free of scratches? October 5, 2022 by 8i9x6 Use the scanner without a document loaded on the glass. Print a test page from the scanner properties. Shine a light on the scanner glass.If it reflects the light properly, it is clean. Load a document that has both graphics and text.Scan the document and examine the output. See Answer Use the scanner without a document loaded on the glass.