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Gram Stain Kit

Ages 12+
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Learn how to differentiate bacteria using the Gram staining method. Identify Gram-positive bacteria & Gram-negative bacteria with this hands-on, top-rated Gram stain kit! Read More

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Use this engaging, 5-star-rated Gram Stain Kit to learn all about differentiating bacteria with the Gram staining method. Inside, you'll find Hucker's crystal violet stain, safranin counterstain, Gram's iodine stain, ethyl alcohol, 12 plain microscope slides, 100 coverslips, a medicine dropper, non-latex gloves, and our own, well-reviewed study guide.

Test different types of bacteria, such as Gram-positive Bacillus cereus and Gram-negative Rhodospirillum rubrum, and compare how the stains differ with the gram stain equipment. (You can also order this bacteria culture comparison set.)

What is Gram Staining? 

Hans Christian Gram, a Danish bacteriologist, discovered that bacteria could be divided into two different groups - one that retained a stain ("Gram-positive") and one that didn't ("Gram-negative"). His method for identifying these two groups - "the Gram method" - became the first step in any bacterial identification process.

How Gram's Method Works:

  1. A sample of bacteria is placed on a microscope slide;
  2. It's then stained and "fixed" with iodine solution;
  3. The slide is then washed in a solvent/decolorizer to "decolorize" the first stain;
  4. Gram-positive cells will retain the stain even after being washed in the solvent, and the stain will be removed from the Gram-negative cells. 
    1. This is because the cell walls of Gram-negative cells contain more lipids (fatty substances). The solvent dissolves the lipid layer, allowing the color to be drawn from the cell. The solvent causes the Gram-positivecell wall to dehydrate, closing the pores and trapping the stain inside the cell. 
  5. In the last step, the Gram-negative cells are stained a different color, to contrast them from the Gram-positive cells.

Gram Staining Science Fair Project Ideas:

  • Discover whether or not antibacterial cleaners work more effectively against Gram-positive or Gram-negative bacteria
  • Find out if common antibiotics equally effective against both Gram-positive and Gram-negative bacteria

Take amazing close-up pictures with your microscope!

Get a great deal on a 2.0 Megapixel Digital Camera from Home Science Tools. You'll be able to take high- clarity images of everything you see under your scope. Plus, it's easy to use! See detailed description >>


WarningWARNING: This product can expose you to chemicals including Methyl isobutyl ketone, which is known to the State of California to cause cancer, and Methanol, which is known to the State of California to cause birth defects or other reproductive harm.



This Gram Stain Kit Includes:

  • Hucker's Crystal violet, 15ml
  • Ethyl alcohol, 30 ml
  • Gram's Iodine stain, 15ml
  • Gram Stain Kit instructions
  • Nitrile gloves, pair
  • Pipet (medicine dropper)
  • Safranin O stain, 15ml
  • Slide coverslips
  • Plain glass slides, 12/pk


Shipping Restriction: This item only ships Economy or UPS to a street address in the 50 US states.
Warning: HAZARDOUS CHEMICAL - This kit contains hazardous chemicals. Not for children under the age of 15. For use under adult supervision. Read warning labels carefully.
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