In-Mold Labeling - What is IML?

Understanding in-mold labeling

In-mold labeling (IML) is a labeling method in which a pre-printed decorative film is placed into a mold before the plastic container is shaped into that mold. Plastic pellets or resin are heated and placed into the mold where it merges with the label to create a single product.

IML Plastic Containers

In-mold labeling is most commonly used for thin-walled disposable items like consumer packaging that have a shorter shelf life. Companies in food, personal care, household and cosmetic industries often use IML to brand their packaging.

Plastic containers with in-mold labeling are manufactured through two methods: injection molding and blow molding.

Types of in-mold labeling processes

IML Injection Mold Process

Injection molding (Pictured above) - In injecting molding, the design label is placed into the mold before fusing together with the container. After the plastic pellets are heated, the resin is injected into the mold where it seamlessly combines with the label.

Blow molding - Blow molding is similar to glass blowing. Like injection molding, the label is inserted into the mold before it is combined with the plastic. However, instead of injecting plastic into the mold, it is blown in using an air stream. Once expanded into the desired shape, the label melds to the container.

4 benefits of in-mold labeling

1) Design quality

In-mold labeling provides high resolution colors and images for labels. IML is compatible with a wide range of colors and can be displayed on both sides of the package. In-mold labeling is a powerful platform for enhancing graphic effects, enabling business owners the flexibility to respond to creative design ideas using flat, curved, or 3D-formed graphics.

The label is fused to the plastic giving the in-mold container a clean, smooth, integrated and unlabeled look as opposed to post-mold labeling (PML). This label remains intact throughout its life and is highly tamper-proof unless the container is cut open.

2) Durability

The water resistance of in-mold labeling makes it a reliable labeling option that can withstand both humid environments and extreme temperature fluctuations (freezing / cooling conditions). In contrast to pressure sensitive labeling, IML is a permanent design method with excellent impact and scratch resistance because it fuses permanently to the container.

A container with in-mold labeling has the potential to be impervious to abrasion and chemicals depending on the hard coatings used to generate the manufactured goods.

3) Environment-friendly

Traditional methods of pressure sensitive labeling require adhesives that are not accepted by every recycling plant. Because both the container and the label are combined without the exterior glue, plastic products with IML can be eco-friendly and fully recyclable depending on the type of plastic resin used to manufacture the product.

Since in-mold labeling containers are completely recyclable, they are eligible to become PCR products which can help decrease carbon footprints and leave a positive impact on the environment.

4) Cost-effective

For mass production, in-mold labeling containers take less time to manufacture because it is produced and decorated in one step to form a single product. In comparison to PML, in-mold labeling is typically more cost-efficient because it is without the expense of time, labor and floor space; IML also reduces inventory like post-mold paper labels and adhesives.

Is in-mold labeling right for you?

While IML has many benefits, in some scenarios conventional labeling may be the best option for you depending on your needs. Here are some factors to consider if IML is the best labeling option for your needs:

High minimum order quantity

Minimum order quantities are typically higher for in-mold labeling compared to traditional labeling methods due to the set-up cost associated with precise positioning and intricate design. For considerable businesses, in-mold labeling is a valuable method because the cost per container is lower in mass production quantities.

Increased lead times

Because IML requires specific mold design and construction for accurate placement and reliability, the time between initiation and completion of the production process can be longer in comparison to other labeling methods.

What materials are used for in-mold labeling?

The two most commonly used plastic types used to manufacture a container with in-mold labeling are high density polyethylene (HDPE) and polypropylene (PP).

IML Food Container

Common in-mold labeling applications

  • Personal care products such as shampoo bottles, deodorants and soaps
  • Food packaging including ice cream tubs, yogurt containers, butter tubs and takeaway containers for soups, salads and confectionaries
  • Cosmetic tubes for sunscreen, lotions and liquid makeup
  • Household products such as bulk cleaning supplies, laundry detergent and fabric softeners

What are some design considerations when using in-mold labeling?

What are your container requirements?

What shape is your container? Round? Square? What surface consistency do you want your container to have? Smooth? Textured? Do you want your container to be clear, glossy, or white? By answering these questions, label suppliers can help determine if the container requires freezer grade, autoclave or ultra-clear resin.

What function will your product be serving?

If your product will be in fluctuating temperature environments, it needs special chemicals that coat and protect the container from harsh conditions so that the plastic remains durable.

IML Food Lid

How big is your container?

If you choose a portion-sized container, say a 5 oz. jar, the ingredient label will not fit on the body of the container and will need to be placed on the lid or at the bottom.

Where do you want your label printed on the container?

Being mindful of where you are printing your label could prevent distortion to your design. Knowing where the plastic is infused into the mold could help avoid labeling on the lump when the injection ends.

Looking for an in-mold labeled container?

We supply customizable printed tamper evident containers and plastic square pails in addition to our design services and other labeling opportunities. If you’re interested in our in-mold labeling solutions, we provide bulk food service packaging and single serve consumer facing retail packaging.

If you need help putting your idea on paper, we also offer custom design services to meet your packaging needs. Our in-house design team can take your ideas and create designs from scratch so that it's made exactly as you envision it. Once your design is complete, we can customize it to suit the bottle or container you are interested in. Schedule a free IML consultation today! -- Call 630.629.6600 or email us at