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Inside the Color Codes of Caps and Closures

Whether in the lab or the grocery store, the color of a plastic cap plays an important role in identifying the contents of a container.

Some cap and closure colors, such as those on blood sample tubes, must adhere to industry standards. Others, including dairy and beverage products in the supermarket, generally share a range of common hues. And still others are designed to impart a sense of luxury, purity or passion to the contents of the container.

Colored Caps and Closures in the Medical Industry

The colors on phlebotomy test tubes contain information not only about what’s inside, but also where the tubes should be in a laboratory.

Tubes are already marked with either 1-D or 2-D scannable barcodes that indicate what coagulants or anticoagulants are present inside with the blood samples. But color-coded caps speed up storage and retrieval times, reduce the risk of lost or misplaced samples and eliminate laboratory errors.

Common tube closure colors include:

  1. Purple or lavender: Utilizes EDTA as an anticoagulant, which helps prepare plasma, whole blood and bone marrow specimens.
  2. Light blue: Contains sodium citrate, which acts as an anticoagulant to prepare citrated plasma for coagulation testing.
  3. Red: Contains no anticoagulant or other additives; typically used for serum or clotted whole-blood specimens.
  4. Gold: Mixes samples with a clot activator and serum gel separator, which is used to prepare samples for chemistry, serology and immunology tests.
  5. Gray: Utilizes potassium oxalate and sodium fluoride to prevent coagulation and preserve the glucose in whole blood for certain chemistry tests.

Voluntary Color Coding in the Food and Beverage Industry

Milk and beverage manufacturers use some fairly standard colors for a couple of reasons: to make shopping easier for consumers and shelf-stocking quicker for store employees.

The most noticeable colors may be on milk cartons. The easy-to-spot caps correspond to the percentage of fat in the milk. While there’s no mandated standard, nearly all manufacturers use red to indicate whole milk.

Other common signifiers include:

  1. Dark blue or green: Reduced fat (2%) milk
  2. Light blue or white: Skim milk
  3. Brown: Chocolate milk
  4. Pink: Strawberry milk
  5. Orange: Half and half
  6. Yellow: Buttermilk

Fruit juices also tend to use shared cap and closure color codes: orange for orange juice, purple for grape juice and red for cherry-flavored juice or fruit punch.

Other types of containers and packages use color to clue consumers in to what’s inside. For instance, green is often found on health foods, vitamin supplements or containers made from post-consumer recycled plastics.

Finally, caps and closures should be coordinated into a product’s overall design and color scheme to appeal to targeted market demographics. Popular colors and what they represent include:

  1. Black: Formality, power, authority, and luxury
  2. Blue: Peace, reliability, sincerity and uniqueness
  3. Green: Growth, fertility, nature and freshness
  4. Orange: Fun, enthusiasm, creativity and low-cost
  5. Purple: Success, nobility, imagination and wisdom
  6. Red: Desire, love, passion, appetite and determination
  7. White: Purity, goodness and cleanliness
  8. Yellow: Joy, optimism, intellect and energy

Caps and Closures with Plastics Color Corporation

Plastics Color Corporation offers concentrates, masterbatches, compounds and liquids in customized colors for use in plastics ranging from container caps and closures to medical and pharmaceutical products. We also provide plastic additives, including antioxidants, impact modifiers, mold releasers and UV stabilizers.

To speak to a representative or engage the services of our Solution Center, please fill out the contact form located at the bottom of this page.

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