Shrink sleeve labels need heat for them to shrink onto the containers they are wrapped around. However, which is the best method for applying heat to these labels? There are actually a few different heat tunnels used for shrink sleeve labels.
The big three are hot air, radiant heat, and steam. All methods have their own merits but deciding which is best overall for you may depend on your preferences. So let’s go over the three.
Hot Air for Shrink Sleeve Labels
Hot air tunnels (also known as convective tunnels) are popular to use for shrink sleeve labels because they can be used by themselves. Hot air tunnels force hot air onto shrink sleeve labels causing them to shrink.
This is usually done by having a heat source and a fan force the hot air out. An example of this would be an industrial hot-air gun. Hot air can be directed to specific areas of the film that places the heat where and when it is needed in the shrink process.
Hot air is often more aggressive than steam and requires careful handling of the packaging materials based on it’s heat resistance. Due to the high heat hot air can go to, you run the risk of melting, or burning your packaging’s label or container.
This method isn’t recommended for products that do not do well with high heat.
Radiant Heat For Shrink Sleeve Labels
Radiant heat tunnels (also known as infrared tunnels) are similar to steam in that they provide a consistent temperature and a high heat energy transfer.
However, they are the most aggressive in terms of heat, and are best used for a fast shrink on packaging material not affected by higher heat. These tunnels use various energy sources from quartz panels, tubes, and in some cases, standard Calrod-style heating elements with reflectors.
Radiant heat is ideal for neck bands on containers such as wine bottles. Radiant or infrared tunnels normally are used in conjunction with other types of tunnels that can serve a finishing unit so may need another heat source to finish the shrinking process for your product if applicable.
Steam tunnels use steam to heat the shrink labels in the shrink process. The benefit to steam tunnels is they have the most uniform heat. With steam, you’re getting 360° all around the package container. This means overall even shrinkage of the shrink sleeve label film.
Steam is also the least aggressive heat of the three tunnel types. Steam tunnels are ideal for round, hourglass, and other non-straight sided packages because of gentle, even shrinkage. PET packaging which stands for polyethylene terephthalate does extremely well in steam tunnels.
However, some companies do not have a water source to draw steam from. Steam machines such as the CoolJarz SST has a water tank from which it uses to create steam. Much of the steam is also funneled back into the water tank to allow for extended use.
There are many methods for applying heat to shrink sleeve labels. CoolJarz SST has gone with a steam tunnel like system because it is capable of applying an even tamper-evident shrink sleeve label all around and works well with most products due to the low heat.