Tagging with dry inlays? These two label constructions can help.

Dry RFID inlays lend themselves to more options for adhesives and custom shapes. Transfer tape and gum twins are the best way to make dry inlays stick.

By Zuzanna Kokot
ECP Associate Marketing at Avery Dennison

More companies are discovering the benefits of tagging products with RFID inlays. Industries as diverse as apparel, beauty, pharmaceuticals, food, and aviation are seeing how creating trackable, traceable, “digital twin” for every item produced can provide unprecedented visibility into the supply chain, vastly improve inventory management, reduce waste, and improve consumers’ brand experience.

At the same time, some companies have confronted a challenge: because of how they’re produced, standard “wet” RFID inlays come in a relatively small range of sizes and shapes and with relatively few options for adhesives. Those limitations make it difficult to be creative with looks and to have reliable adhesion to challenging surfaces, or guarantee the label performance of the products exposed to heat or cold, and on smaller items. Because they’re generally designed to be permanent, wet inlays also make it hard to create tags that can be easily removed. For all these reasons, wet inlays aren’t a practical solution for many products.

Fortunately, the solution is as simple as using dry inlays instead of wet ones.

The difference between wet and dry

Simply put, wet inlays come with pressure-sensitive adhesive, and dry inlays don’t. In the manufacture of dry inlays, the chip and antenna are placed on a carrier, or substrate, which is usually made of film or paper material. They are supplied to printers on a roll or sheet with registering marks to facilitate the conversion. A facestock and adhesive could be added during conversion and laminated with the inlay, and this construction is then die-cut to specification.

Alternatively, dry inlays could be converted into wet inlays by the supplier through adding a standard pressure-sensitive adhesive —usually acrylic or hotmelt— along with a backing liner. The inlays are then die-cut to one of several specific shapes and sent to the label converter. This format facilitates the insertion operation during the label conversion, but limits the choices on adhesive. Eventually, a wet inlay could be used as a simple finished RFID label.

The question for brands and printers using dry inlays is: What’s the best way to turn the inlays into a tag? In other words, with no adhesive coating, how do you make dry inlays stick? An effective way to do that is by combining dry inlays with one of two special label constructions: transfer tape or gum twins.

Enter transfer tape and gum twins

Transfer tape and gum twins were designed to make any material self-adhesive, and that’s the function they provide for dry inlays.

Transfer tape consists of a layer of adhesive between two liners. Gum twins are made of facestock coated on both sides with adhesive, and two liners; the facestock in gum twins adds a bit of support. In both cases, users can choose from a broader range of adhesives than with wet inlays. And in both cases, the adhesive is added to the inlay during the conversion process.

Transfer tape and gum twins are both proven solutions. Gum twins are often used for product inserts in magazines, for permanent mounting, as in photo albums, for food reclosures, and and on sealable products like envelopes. Transfer tape is mainly used to create custom labels with a high level of complexity.

Gum twins are often the preferred solution for RFID, due to the ease of conversion. In gum twin constructions, the adhesive “holds on” to the face material providing a trouble-less conversion. Additionally, the facestock layer in gum twins can have different color and opacity, which is a desired feature for security applications in particular. And gum twins labels are sturdier overall for handling. Transfer tape, on the other hand, offers a more economical solution than gum twins, and is often suitable for labels where caliper and overall thickness need to be kept to the minimum.

When to use them?

Both gum twins and transfer tape offer a solution for attaching dry RFID inlays in applications where wet inlays won’t work. Here are some of them:

Challenging surface. Wet inlays work best on cardboard and paper. For curved or rough surfaces, or those likely to be contaminated with dust or moisture, dry inlays are the better choice, because they allow users to apply an adhesive that will hold up better in such surfaces.

Extreme environments. For RFID tags that will be applied or deployed in hot, cold, or wet conditions, dry inlays can be made with adhesives engineered to withstand such environments, ensuring reliable adhesion and ongoing RFID functionality. Using gum twins for the tag, particularly, provides extra reinforcement, thanks to the presence of face material covered on both sides with adhesive.

Creating a removable tag. Most standard adhesives used with RFID tags are permanent. But some products, like clothing, electronics, and multiple-use logistics packaging, require tags that users can remove. Dry inlays paired with gum twins covered on one side with removable adhesive are perfect for this application.

Look and shape. Surface, reading environment, memory requirements, the size of the decorated label, and the size and shape of the item itself all dictate the size and shape of an item’s RFID tag. Dry inlays offer more choice for sizing and shaping the inlay to fit the application. One example is jewelry: “rat tail” RFID tags, small barcode labels with a longer strip of paper extending from one side, are frequently used on rings.

Going dry

In all, dry inlays allow for greater customization in size and adhesive than wet inlays, letting brands add the benefits of RFID to products not suited to wet inlays. At the same, dry inlays give label printers more potential lines of business. Transfer tape and gum twins are an effective way to make sure tags made with dry inlays stay put and do their jobs.

Read more about transfer tape and gum twins in our technical guide — or find out how to get started with RFID at label.averydennison.com/rfid

Zuzanna Kokot, ECP Associate Marketing at Avery Dennison

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