DWS has built work in Colorado, Texas, British Columbia, Utah and New Mexico.
Gram Staining: A. Add crystal violet stain over the fixed culture. Let stand for 10 to 60 seconds; for thinly prepared slides, it is usually acceptable to pour the stain on and off immediately. Pour off the stain and gently rinse the excess stain with a stream of water from a faucet or a plastic water bottle. Note that the objective of this step is to wash off the stain, not the fixed culture. B. Add the iodine solution on the smear, enough to cover the fixed culture. Let stand for 10 to 60 seconds.
Lab #3: Unstained Preparations and Simple Stains. Summary: Students practice all prior skills and are introduced to preparing slides for. staining and how to use the oil immersion microscope. The follow-up lab, the Gram. stain, is more involved and so perfecting techniques such as how much bacteria is placed. on the slide, flaming the slide and the use and cleaning of the microscope are introduced. here. Grade Levels: 9-12.