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Quality Control of Barrel Bungs

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Quality Control of Barrel Bungs

Feb 5, 2024
Quality Control of Barrel Bungs

At Cincinnati Dowel, we offer the largest product category of bungs in the United States. We supply over 95% of the barrel bungs that distilleries and cooperages use today throughout North America.  

Our large market presence continues to grow because we are committed to creating quality wood products by manufacturing a wide range of sizes and species of bungs for all your specific needs. 

We create barrel bungs by transforming raw lumber into a round piece of wood, that can take on different attributes and sizes, depending on the application. Our uniquely designed site equipment and machinery make us the leader in quality as well as the ability for large-scale production.  

After our bungs are created, we make sure that they go through a thorough quality control process.    

In every manufacturing process, quality control is very important.  

However, it is especially essential for bungs because a watertight seal is imperative to its function which prevents the loss of distillate.  

In this article, we will explain where we get our materials, our quality control process and procedures, and how we keep the bungs safe during shipping.  

Where Our Materials are Sourced 

wooden bungs
Different bung categories (left to right), Premium, 1st Quality, Seconds, Burns.


At Cincinnati Dowel, we are proud to source all our material from Appalachian hardwoods, which can come from anywhere within the states of Indiana, Ohio, Kentucky, West Virginia, and Pennsylvania. These areas are known for their high-quality hardwood and are committed to using the finest materials for our products. 

Lumber is graded based on the number of defects present on the board. Any boards that fall below a certain grading threshold are promptly returned, as we do not compromise on the quality of our materials. 

These grades confirm that the wood is of exceptional quality, with minimal defects. This attention to detail and insistence on high-grade materials allow us to produce durable and reliable bungs and other wood products for our customers. 

Our commitment to using only the best hardwood allows you to receive top-notch, long-lasting products for all your woodworking needs. 

Bung Quality Control Process 

Vibrating bowl on the automatic sorting machine which feeds bungs to conveyer belt so they can be examined by the QC cameras.


At Cincinnati Dowel, we verify that our barrel bungs are high-quality by going through a meticulous quality control process.

This process is done by using a bung sorting machine that was custom-built for us. 

The sorting machine primarily sorts our standard 2” poplar and white oak bungs. Other less common and custom sizes are still sorted by hand.  

For our standard 2” diameter bungs, we utilize an automated sorting machine that has three state of the art triple imaging inspection cameras and lasers that can check for all dimensions and defects of a barrel bung.  

These cameras examine the top (diameter), side (taper and thickness), and bottom (diameter) of the bungs, checking for thickness, diameter, taper, and out of roundness.

Additionally, all three cameras also look for color, knots, cracks, flat spots, and other various defects. 

After inspection, the machine sorts the bungs into their various grades.   


Below, we have outlined our barrel-bung quality control steps using the sorting machine.  


First, we have a Quality Inspector manually check the diameter and angle of the taper continuously on all bung throughout the day. Given the number of machines we have running at the same time, this means each machine is checked approximately every 15 minutes.  This is done to make sure that the machines are calibrated correctly. This is essentially the first line to identify and resolve any potential defects or machine “issues.” If any error is discovered, the machine is shut off and recalibrated.   

The next step is the sorting process which utilizes our state-of-the-art sorting machine. 

Unsorted bungs are dumped into a large steel hopper where they vibrate up the bowl and are carried along a conveyor belt through the sorting machine where the three cameras and lasers check the quality.  

The sorting process categorizes bungs into four different categories. It's important to divide the bungs into separate categories because of their various applications.  


Premium First Quality Bungs: 


These are #1 quality that are free from defects and are also sorted for color and major indentations. This applies to customers requiring a bung that is free from color streaks or machine indentations. 


First-Quality Bungs:  


First-quality bungs are versatile and can be used in various ways. These are the same as premium bungs but are not sorted for color or indentations. 


Second-Quality Bungs:  


This kind of bung may have minor knots and other small imperfections, but it is still a quality product.  

Second-quality bungs are used in a multitude of ways that do not require a watertight seal.  


  • Place holders in barrels
  • Insulation plugs
  • Paper core plugs
  • Any other instances that do not require a watertight seal 

We encourage customers interested in second-quality bungs to contact us for further information


Third-Quality Bungs:  


These are also referred to as 'burn bungs'. These bungs have compromised structural integrity, have major chunks missing, are extremely over or under-sized, or are not able to be used as a plug. 

These are burned as fuel to feed the kiln, which dries our green lumber, or the boiler, which heats our facility. 

How We Protect Bungs in Shipping 

bung sorting table
Sorting table used for manually sorting larger or custom bungs by hand. 


We make sure that our bungs stay safe during shipping by taking the necessary precautions to protect them from any potential damage during transportation. 

One of the key measures we take is the use of a plastic liner to keep moisture out to prevent the expansion or contraction of bungs which can compromise the quality of the product.  

In addition, the liner serves as a barrier that shields the bungs from external elements that could potentially cause harm. It acts as a protective layer along with a reinforced, side-seamed, corrugated box, minimizing the risk of any damage occurring during transit. 

Ultimately, the liner allows you to receive your order of bungs in top condition, ready for immediate use!  


Quality Barrel Bungs with Cincinnati Dowel  


At Cincinnati Dowel, we are committed to providing high-quality bungs through stringent quality control measures.  

By implementing thorough inspection processes and utilizing the latest technology, we make sure that our products meet the highest standards for reliability and performance.  

We are dedicated to quality control, not only to maintaining the integrity of our products but also to instilling confidence in you that each product you purchase from us is top-notch.  

Our attention to detail and commitment to excellence set us apart as a trusted supplier of top-notch bungs for a wide range of applications.  

You can rely on Cincinnati Dowel to deliver bungs that exceed expectations and stand the test of time. 

To browse our full selection of bungs and other products, click here!  

Happy with the difference Cincinnati Wood products have made for your operations? Leave us a five-star review on Google here!  

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