Metal Container Anatomy: Inside & Out

As the industry’s Metal Container leader since 1938 Freund Container has your answers for better packaging solutions.

WHY CHOOSE METAL? Metal is one of the most abundant raw materials, offering superior content protection and provides a very low environmental footprint.

Metal Liner Types:
C-Enamel liners work great for low acidic foods. For prolonged storing of foods with low acidity, however a discoloration of the metal surface can occur.
White Enamel liners are ideal for higher acidic foods, such as beets, berries, tomatoes, etc.
Epoxy liners are for most water and latex based solvents and increase chemical stability.
Laquer liners are FDA approved and work well for acidic food and aggressive solutions.

Frequently Asked Questions:
Heated Metal? Tinplate heat up to 450°F (230°C). Stainless Steel and Carbon can be heated to 2600°F.
Rusting Metal? Much of our metal is treated with a rust inhibitor, but not rust preventer. Rust is based on moisture and oxygen and however much exposure a container gets to either one of these post manufacturing is what will determine if any, how much rust you will incur. Testing is recommended with your product.


anatomy of a can 










Bead: concave (interior bead dot) or convex (exterior bead dot) area usually 1/8″ wide spanning the circumference of the tin to provide additional strength and stability to the tin bodyBody: a can without a cover (lid); the base of a containerCover: a can’s lid or closureCurl: area of tin turned in on itself to provide a safe, finished curved edge dotDome: a type of cover characterized by a flat horizontal surface (top) that tapers smoothly onto the skirt (vertical surface) dot

Drawn: see seamless

End: the area of a tin also known as the bottom. Coffee-style hermetic tins generally have two ends. Ends can be attached by seaming them on or crimping dot

Full friction: a plug-style metal cap fits snugly to the interior of the can dot

Hem: similar to a curl, an area of tin turned in on itself to provide a safe, finished flattened edge

Interior Friction: Cover/closure option in which a pliable ring fits to the interior of a tin allowing for a straight-sided slender profile can

Lock-seam: side walls meet and attach by hooking onto one another to form a tin body dot

Multiple friction: a plug closure fits into a “well” of a seamed-on ring. The plug is pressed into the ring and the two surfaces (the outside and inside edge) come into contact with the ring, creating multiple sealing surfaces on the plug/ring combination dot

Seamless: a tin that is constructed from a single piece of tin drawn to form the body of the can

Single friction: a plug-style metal cap fits snugly into a seamed on ring. The outside edge of the plug presses against the interior edge of the ring, creating one sealing surface dot

Slip cover: cover/closure style in which the cover’s skirt (vertical surface) slips over and to the outside of the can body dot dot

Stepped cover: type of slip cover in which a “step” is created between the horizontal surface and vertical surface of the cover so that stacking tins is possible with less likelihood of toppling over dot

Welded Seam: seam type in which side walls attach to one another through the use of heat to form a tin body dot

White Coat: entire surface of the metal is coated with white before applying other printing ink colors



Types & Terminology – Glass Containers

Chances are good that glass containers never receive a second thought, but simply sat in your refrigerator or medicine cabinet or on the pantry shelf.  Knowing your glass bottles, jars, jugs, and vials is important if containers are your business!  At Freund we love Glass and are taking a moment to share our knowledge about glass types and terminology.  Freund Container is an industry leader when it comes to glass with the broadest selection at unbeatable prices.

Types of Glass: Glass containers are made from silica sand, soda ash, limestone, alumina and other additives as needed. There are three different types of glass.

Type I – A borosilicate formulation, this type is usually reserved for parenteral (injectable) products, particularly those that are alkaline in nature. It is 10 times more durable than soda glass.

Type II – A soda-lime glass treated with sulfur in the annealing phase to reduce alkali solubility. It is used for parenterals – sometimes alkaline, but more likely acidic or neutral.

Type III – A regular soda lime (flint) glass that has been tested and shown to be at or below a specified extractives level. It is intended for more sensitive products, but usually is not used for parenterals.

Glass Container Terminology: Blown glass containers tend to fall into two categories: Narrow Neck and Wide Mouth Jars. Most commonly glass is found in two different colors, flint – clear or amber – brown color. Also, glass can be found in cobalt blue or sometimes with a greenish tint. There are secondary processes that can be done to frost the glass or tint custom colors. As with most packaging forms, there’s a distinct terminology associated with blown glass containers. Each term will be explained and Figure 1 diagrams the locations of the points that will be explained.

Sealing Surface – The flat, circular top surface of the finish in which the closure will form a seal. It’s also termed the “land”. If this is not flat, the container could leak.

Finish – The top part of the container, above the neck, shaped to accommodate a specific closure.

Thread – A small spiral-shaped protruding glass ridge on the finish of a container intended to mesh with a similarly sized screw-type closure to seal the container.

Neck – That portion of the container that is above the shoulder and below the finish. The neck is where the cross-section of the bottle grows smaller to join the finish.

Neck Ring or Bead – Protruding ring just above the neck-ring parting line. All glass bottles have this so they can be removed from the machine.

Mold Seam – The slight vertical ridge of glass that runs through the neck ring and the rest of the finish. The seam indicates where two halves of the finish molds were joined.

Shoulder – That part of the bottle between the main body and the neck.

Body The main part of the bottle where the sidewalls are usually vertical.

Bottom – The entire lower part of the bottle below the sidewalls. The bottom includes the heel, base and push-up. The bottom may have letters and symbols molded into it that indicate the number of the mold cavity that produced the container and the manufacturer. The manufacturer symbol is called a “punt mark”. The bottom also may have a small projection that serves as a registration device for labeling and decorating equipment. The device also can take the form of a small recess along the heel of the container. This is also a good spot for a customer name or company logo.

Heel – That lower part of the bottle where the glass in the sidewall turns from vertical to horizontal. The heel joins the sidewall to the bottom-bearing surface and may have a small recessed spot that serves as a registration device for labeling and decorating equipment.

Base – An even bearing surface that forms a ring around the outside of the bottom upon which the bottle rests. This ring usually is given a stippled finish in the mold to mask scratches that occur during handling and concentrate abrasions on the stronger high points of this raised pattern, thus, preventing the container from being weakened. The base is inside and underneath the heel and surrounds the push-up.

Push-up – An inward dome in the center of the base. The resulting ring around the outside of the bottom provides an even bearing surface upon which the bottle rests.

What is your favorite glass container?  Share your ideas and company products with us!

Cash Management: Sweating Your Prime Asset

Economies around the globe are sputtering again! Headlines from nearly all leading news sources cast a shadow on recent recovery talk. America’s jobless rate is up. Europe is on the brink of collapse: Greece is teetering on bankruptcy; Spain, Italy and Ireland have seen their credit ratings slashed. What’s a company to do?

For most companies, CASH is their prime asset – a resource you deploy nearly every day. Nearly every article on the cash management focuses on cost cutting or reducing your collection cycle. Both are fundamental to an enterprises financial health.

There are a great many other variables that must not be ignored when solving the “Cash Management” riddle. When sourcing, do you factor in the cost to carry and store products? Do you consider the “opportunity” cost associated with the investment? Which is to answer this question: will another investment option produce a higher rate of return? After all, we all want to make more profits.

Fresh Perspective …

Have you considered slashing inventory levels to precisely what you need for a narrow production window? If you have, you likely dismiss the idea when you think about long vendor lead times and the impact it might have on your customer service. What if you had a trusted vendor partner that would guarantee your items will be in stock precisely when you need them? Moreover, they would ship on-time 99.9% of the time. Depending on your business position, these practices make more CENTS. Smaller cash outlays for product will allow you to invest in higher-yield investments (more PROFITS); or, provide you the cash cushion needed to be resilient during these tough economic times.

Freund Container & Supply is a trusted packaging partner dedicated to helping you grown your Net Income!

Contact Chris Soltis at Freund Container & Supply 800.363.9822 to improve your cash management. FREUND – your lowest cost supplier GUARANTEED!

Your Guide to Plastic Resins

Your Guide to Plastic Resins

If you are looking for a plastic resin container, the following information will serve as a guide to help you in your selection. However, this information can only illustrate the many varieties of plastic resins that are available. Therefore, these descriptions are intended only as a manual to explain the options available, and you should not ignore compatibility testing to determine the container most appropriate for your purposes. All buyers are ultimately responsible to consider these descriptions and to examine their applications before deciding which containers, closures, and accessories best meet their needs.


Created with durable materials, PET and PETG containers demonstrate a gloss and clarity that make this resin perfect for use in food and beverage containers. This resin gives the look of glass, but because it is made of plastic, it features an increased resistance to strong impacts and breakage. Foods, beverages, personal care products, and pharmaceuticals are safer and more secure in a PET or PETG plastic resin container. In addition to these display and safety features, PET and PETG bottles and jugs are lightweight and convenient alternatives to more fragile glass containers.

Low Density Polyethylene (LDPE)

 Although very similar to HDPE containers, the LDPE composition is less rigid. This allows containers made from this resin to be even more flexible and therefore squeezable. Products such as shampoo, conditions, and adhesives are typically packaged in LDPE containers because they are so elastic. Because LDPE is less chemically resistant than HDPE, these containers are typically glossier in appearance. The glossier appearance makes them ideal for food and personal care products. 

High Density Polyethylene (HDPE) 

 Making it the most widely used resin in plastic bottles, HDPE is known for being both extremely durable and very economical. This plastic resin is naturally translucent in appearance, but that does not prevent it from being somewhat flexible and very resistant to impacts. Although HDPE cannot be used to contain solvents, it works very well with acid concentrates and some caustics. This application has made it a favorite for FDA-approved food grade products. Color can be added to the HDPE plastic to make it more opaque, but even with this addition, it will not become glossy. These containers can be used to hold substances at below-freezing temperatures, but anything heated to over 180 degrees Fahrenheit or anything requiring a hermetic seal cannot be enclosed in a HDPE container. 


Polypropylene (PP)  

 For products needing to be stored at high temperatures, PP containers are an excellent option. This plastic resin is exceptionally stable at high temperatures while providing a strong moisture barrier. Foods and beverages that are heated, such as pancake syrup, are well-contained in bottles and jars created from PP materials. This resin is also autoclavable, meaning that it can withstand the steam sterilization process created by high temperatures and heavy pressure. Because of these storage characteristics, PP preserves dried foods such as spices, dried fruit, and flour exceptionally well, trapping in the freshness and flavor. Although PP performs well in high temperatures and under strong pressures, it has very poor impact resistance, especially in cold temperatures. 


Polystyrene (PS)   

This plastic resin most closely mimics the appearance and strength of glass. With a strong, clear crystal appearance, PS also creates an oxygen barrier that serves to preserve the freshness of the products held inside. However, this resin does not respond well to changes in temperature or ultraviolet exposures. In addition, it has poor to moderate resistance to impact, much like the glass that it imitates.


Polyvinyl Chloride (PVC)  

Polyvinyl Chloride containers have a variety of uses due to their high resistance to oils and low oxygen transmission. With these attributes, this semi-rigid PVC resin is very resistant to chemicals. In addition, PVC provides a solid barrier to most gases, making it a strong selection for salad oil, mineral oil, and vinegar. Personal products such as shampoos and cosmetics are frequently contained in PVC as well. Although this resin is chemically resistant, it cannot contain solvents or be heated to more than 160 degrees Fahrenheit as these conditions can cause the resin to distort.



Primary Container Closures: Don’t Get Them TWISTED!

Caps & ClosuresA dizzying array of container closures can be found in the rigid packaging market. Understanding the different types of closures will help you select the correct one. Each closure type performs a unique function. Here, we’ll focus on the two most common closure styles: continuous thread and lug style closures.

Continuous Thread Closures:Continuous Thread Closures

Continuous thread closures (also known as CT Finish Caps) are easily recognized by an unbroken, raised, spiral track on the inside of the cap. When mated to a container, the two spiral edges interlock in roughly 1 ½ turns, resulting in a tight, secure seal.

CT closures are available in both plastic and metal and successfully secure most contents, even when containers are tipped momentarily. Threaded closures, however, are not by default “LEAK-PROOF”. A definition of “LEAK-PROOF” systems is provided below.

Clearly, CT closures are utilitarian workhorses! They’re available with either a ribbed or smooth outer finish. Vertical ribbing on the outer finish provides superior gripping power for twisting closures – a useful feature when users’ hands are wet or slippery. CT closures are ideal for nearly any end-use application including chemical, health and beauty, automotive aftermarket, food and beverage, and medical products.

Lug Finish or “Quick” Twist Closures:

Lug Finish or Quick Twist Closures may be found on metal closures. Unlike their close relatives above, the spiral thread is intentionally broken to provide quick opening and closing. You’re likely thinking this compromises the closures sealing ability – that’s not entirely true. Rather than compromising its performance, this unique broken thread allows lug caps to seal in a quarter turn. Quick and easy opening and closing in a snap. Caps with this finish style are commonly used in canning products like jams and sauces, as well as beverage containers such as ice tea, juices, and other drinks.

Leak-Proof Container Systems:

You’re likely thinking, “Systems? I thought this was an article about closures.” Yes, leak-proof containers are sold as systems. Leak-proof container systems feature unique, interlocking threads on both the cap and container. Apply the closure to the container using the correct torque (twisting force) and the result is a leak-proof system – guaranteed. Two companies dominate this space: Nalgene and Kautex. Freund Container & Supply sells both and is proud to be North America’s exclusive Kautex supplier. Their unique design and relatively low sales volume drive their cost up. Cost aside, they deliver leak-free performance time and time again.

Now that we’ve covered basic closure styles, you should visit our Cap Sizer & Liner Definitions to learn about liner types, cap sizing, forming a seat seal, and about dispensing cap options or shop for Caps, Closures, and Liners now.