How to Date Kerr Canning Jars?
Dating Kerr canning jars involves examining distinct manufacturing features, including the jar style, logo, and embossing details; this analysis allows you to estimate the jar’s age and learn about its history, though providing an exact date is usually impossible without associated documentation.
Understanding the History of Kerr Canning Jars
Kerr Glass Manufacturing Corporation played a significant role in the home canning movement, producing jars and lids for decades. Founded by Alexander H. Kerr in 1903, the company initially focused on making glass lids for food containers. As home canning grew in popularity, Kerr expanded into manufacturing complete canning jars, becoming a prominent name in the industry alongside Ball Corporation. Understanding the evolution of Kerr’s branding and manufacturing processes is crucial for dating their jars.
Benefits of Dating Kerr Canning Jars
Dating Kerr jars isn’t just about historical curiosity; it offers several practical benefits:
- Identifying Collectible Jars: Some older or rarer Kerr jar styles can be quite valuable to collectors.
- Assessing Jar Safety: While glass jars can last a long time, jars with chips, cracks, or other defects should not be used for home canning. Dating helps you identify potentially older, weaker jars.
- Historical Insight: Dating jars can connect you to the history of home food preservation and the families who used them.
- Personal Connection: Perhaps you’ve inherited jars from a family member. Dating them can add a deeper personal connection to the objects.
The Dating Process: Key Features to Examine
Dating Kerr canning jars involves careful observation of several key features:
- Logo Style: Kerr’s logo underwent several revisions over the years. Observing the font, spacing, and overall design of the “Kerr” logo is a primary method for dating.
- Jar Shape and Design: The shape of the jar, including the shoulders, neck, and base, changed over time. Some shapes were only produced for specific periods.
- Embossing Details: The specific wording and placement of embossing (raised lettering) on the jar offer important clues. This includes information such as “Kerr Self-Sealing Wide-Mouth Mason” or location information such as “Sand Springs, OK.”
- Closure Type: The type of lid and closure system used with the jar changed over time. Early jars used glass lids with wire bails, while later jars used screw-on metal lids.
- Manufacturing Marks: Imperfections or inconsistencies in the glass can provide clues about the manufacturing process and era. Look for seam lines, bubbles, and other subtle details.
- Color of the Glass: While most Kerr jars are clear glass, some were produced in different colors, such as light green or aqua, which can help narrow down the production period.
Common Kerr Jar Dates and Associated Features
This table provides a general guide to dating Kerr jars based on logo style and other features:
| Time Period | Logo Style/Features | Closure Type | Common Embossing |
|---|---|---|---|
| 1903-1910 | Block lettering “Kerr” with a separate “Economy” underneath | Glass lid with wire bail | “Kerr Economy Jar” |
| 1910-1915 | “Kerr” in an italicized script font, often with serifs. | Glass lid with wire bail | “Kerr Self Sealing Jar” |
| 1915-1930 | Similar script font, but often bolder and more pronounced. Transition to metal screw-on lids. | Metal screw-on lids becoming common | “Kerr Self Sealing Wide-Mouth Mason” |
| 1930-1960 | Block lettering “Kerr” with a more modern, streamlined design. The logo becomes more consistent. | Metal screw-on lids | “Kerr Mason” or “Kerr Self-Sealing” |
| 1960-Present | More simplified block lettering. Continued use of metal screw-on lids. | Metal screw-on lids | Often simply “Kerr” with capacity markings (e.g., “Pint,” “Quart”) |
Common Mistakes When Dating Kerr Jars
Dating Kerr jars can be tricky. Avoid these common mistakes:
- Relying Solely on One Feature: Use multiple features (logo, shape, embossing) to cross-reference your findings.
- Ignoring Manufacturing Imperfections: Don’t dismiss bubbles or seam lines; they can be valuable clues.
- Confusing Kerr with Other Brands: Be certain that the jar is, in fact, a Kerr jar. Look carefully at the logo to avoid misidentification.
- Overestimating Precision: Without documentation, you can usually only estimate a date range, not a specific year.
Conclusion
Dating Kerr canning jars offers a fascinating glimpse into the history of home food preservation. By carefully examining the logo, shape, embossing, and closure type, you can estimate the age of your jars and learn more about their origins. Remember to consider multiple features and avoid common mistakes to arrive at a more accurate assessment.
Frequently Asked Questions (FAQs)
What is the best resource for researching Kerr jar dates?
The best resource is often a combination of online guides, collector forums, and books dedicated to antique canning jars. Websites like Minnetrista’s Ball State archive and user-submitted databases can offer valuable insights, but remember that information accuracy can vary. Checking several sources is always recommended.
Can I use old Kerr jars for canning today?
While you can use older Kerr jars, it’s crucial to inspect them carefully for any chips, cracks, or other damage. These flaws can weaken the glass and increase the risk of breakage during the canning process. Using newer jars is generally safer if you are unsure of the condition of older jars.
What does “Self-Sealing” mean on a Kerr jar?
The term “Self-Sealing” refers to Kerr’s innovation in developing a lid that creates a vacuum seal during the cooling process after canning. This seal prevents spoilage by keeping air and microorganisms out. This innovation was revolutionary at the time.
Are jars marked with “Sand Springs, OK” more valuable?
Jars marked with “Sand Springs, OK” indicate that they were manufactured at the Kerr Glass Manufacturing Corporation plant in Sand Springs, Oklahoma. The value of these jars depends on their rarity, condition, and collector demand. While the Sand Springs plant was important to Kerr’s history, not all jars from this location are automatically valuable.
How does the color of the glass affect the date of a Kerr jar?
While most Kerr jars are clear, some were produced in light green or aqua glass. These colored jars were typically manufactured in the earlier years of production (roughly pre-1930). Finding a colored jar is a strong indicator that it is relatively old.
What is the difference between a Mason jar and a Kerr jar?
“Mason jar” is a generic term for a glass jar used in home canning, named after John Landis Mason, who patented a screw-top jar in 1858. Kerr was one of many manufacturers that produced Mason jars. Both Kerr and Ball are well-known makers of Mason jars.
What are some signs that a Kerr jar is not safe to use for canning?
Signs that a Kerr jar is unsafe for canning include chips, cracks (especially near the rim), hairline fractures, or a rough sealing surface. Also avoid jars with bulges or irregularities in the glass. These defects can compromise the jar’s ability to withstand the heat and pressure of canning.
How can I clean vintage Kerr jars without damaging them?
To clean vintage Kerr jars without damage, use warm water and a mild dish soap. Avoid abrasive cleaners or scouring pads that can scratch the glass. For stubborn stains, try soaking the jar in a solution of vinegar and water. Gentle cleaning is key to preserving the jar’s condition.
Where can I find more information about Kerr jar values?
Finding Kerr jar values can be challenging as they fluctuate based on condition and collector demand. Online auction sites (like eBay) and collector forums can provide some insight, but professional appraisal is best for accurate valuations.
What does it mean if a Kerr jar has bubbles in the glass?
Bubbles in the glass are common in older Kerr jars due to the manufacturing processes of the time. While a few small bubbles are usually not a concern, a large number of bubbles or a large bubble near the rim could weaken the jar. Excessive bubbles should be evaluated with caution.
Are commemorative or limited-edition Kerr jars more valuable?
Commemorative or limited-edition Kerr jars can be more valuable, especially if they are in pristine condition and come with original packaging. Rarity is a key factor in determining their value. Researching the specific edition and its historical significance is essential.
What is the best way to store Kerr jars to preserve their condition?
Store Kerr jars in a cool, dry place, away from direct sunlight. Avoid stacking them directly on top of each other to prevent scratches or chips. Wrapping each jar in acid-free tissue paper can provide additional protection. Maintaining a stable environment is key for preserving vintage jars.