Choose Thermo Ink
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Choose Thermo Ink

Picking the right thermochromic effect is not only about colour change. It is about matching the trigger temperature, print method, packaging material and supply chain conditions so the pack performs from Jacobs to the final shelf.

1. Start with the job the pack must do

Begin by deciding what the ink must tell the customer. Some packs need a clear temperature cue for chilled goods, others need a visual reminder for heat exposure, and some need a feature that also helps with authenticity. The right choice depends on whether the pack must signal safe handling, open time, storage limits or tamper control.

For South African conditions this matters more than many teams expect. A carton moving through Durban heat, a cold chain in Gauteng, or a container crossing the coast can all affect how quickly the effect appears. We always start with the product, the pack format and the route to market before recommending a trigger point.

  • What item is being packed?
  • What temperature should trigger the colour change?
  • Will the pack travel in cold rooms, trucks or coastal humidity?
  • Does the effect need to be subtle or highly visible?

2. Match the trigger temperature to real use conditions

The trigger temperature is the point where the ink starts to change. A small shift can make a big difference. Too low, and the pack changes when it should not. Too high, and the message comes too late. For chilled foods, cosmetics, pharmaceuticals and moisture-sensitive goods, the right threshold must be chosen around the actual storage and handling range, not a guess.

We use threshold tuning and drawdown panels to test different options before full production. That lets your team see how the colour behaves after printing, drying and curing. It also helps identify whether the chosen effect will still read clearly after folding, sealing or stacking. On busy lines, even a 2 to 3 degree difference can change the result.

  • Confirm the intended storage range in degrees Celsius.
  • Check whether the pack will see short heat spikes or long exposure.
  • Test the effect after full drying, not only straight from print.
  • Keep one retain sample from every approved batch.

3. Check the substrate before you choose the ink

Thermochromic and security inks do not behave the same way on every surface. Board, film, coated labels and laminated cartons all need different handling. Adhesion, rub resistance and coating compatibility should be checked before you commit to a production run. If the surface is too slick or too porous, the print can lose clarity or wear too quickly.

In Jacobs and at converter sites nationwide, we often review the full print stack, from substrate to overprint varnish. That saves time and reduces waste. Coastal humidity can also affect drying and storage, so a pack that looks fine in the factory may behave differently once it sits in a warm warehouse or a container yard.

  • Confirm whether the substrate is coated, uncoated or laminated.
  • Test adhesion after curing and after 24 hours.
  • Run rub resistance checks for transport and shelf handling.
  • Review how the ink works with any topcoat or varnish.

4. Decide whether you need colour change only or added security

Many packaging teams start with thermochromic colour change, then add a security layer once they see the value. If the pack must also help with authentication, the design can include security patterns, verification features or a custom response that is harder to copy. That is useful for higher-risk products, controlled distribution and premium ranges.

Security inks should not clutter the pack. They need to support the brand and remain practical for the line. We work on security pattern design, UV verification setups and production troubleshooting so the effect still prints cleanly at speed. The best result is a feature that is easy for your team to check and difficult for others to replicate.

  • Choose a visible cue for the consumer and a separate cue for verification if needed.
  • Keep the security element consistent across the pack format.
  • Test how the feature reads under normal light and UV.
  • Store approved samples in the batch retain library.

5. Run a proper trial before full production

A trial batch is the safest way to confirm the final choice. Small production runs let you check colour intensity, print stability, drying time and press behaviour without risking a full order. We use trial batch making and press startup support to confirm that the chosen ink runs correctly on your machine settings and your production speed.

During the trial, watch for edge lift, uneven coverage, blocked screens and colour drift. If something looks off, it is easier to adjust the formulation or setup early. This is especially important when the pack has tight registration, fine text or a combined decorative and security print. A good trial prevents expensive rework later.

  • Approve the visual result under shop floor and daylight conditions.
  • Check line speed, drying and curing settings.
  • Review start-up waste and make any needed adjustments.
  • Record the approved settings for future repeats.

6. Plan supply, storage and repeat orders from day one

Once the effect is chosen, think beyond the first run. Thermochromic and security inks should be stored correctly, tracked by batch and ordered with enough lead time to avoid line stoppages. For converters in Johannesburg, Pretoria, Pinetown, Prospecton and beyond, dependable replenishment matters as much as the formulation itself.

We keep a practical view of production. That means clear batch records, retained samples and logistics that suit live manufacturing schedules. If your operation is affected by load-shedding or tight dispatch windows, the plan must include that. Good ink selection is not only about performance on the press, it is about keeping your packaging moving week after week.

  • Keep stock in a cool, dry area away from direct sunlight.
  • Use batch codes and retain samples for repeat orders.
  • Allow enough time for testing before a launch or reprint.
  • Confirm delivery timing with your production schedule.

Questions we get asked

How do I know which thermochromic threshold to choose?

Start with the product temperature range and the real handling conditions. The threshold should reflect how the pack is stored, transported and displayed, not only the ideal specification on paper.

Can thermochromic ink work on different packaging materials?

Yes, but the substrate matters. Board, film, labels and coated cartons all need compatibility testing, plus adhesion and rub checks before full production.

Do I need security printing as well as colour change?

If the pack needs authenticity control, security printing is worth considering. A combined solution can give a visible temperature cue and a separate verification feature for your team.

More guides

UV Check Guide

UV Check Guide

A simple guide to setting up consistent UV verification in packaging operations.

Flexo Trial Guide

Flexo Trial Guide

How to set up a controlled flexographic trial for special packaging inks.

Carton Effects Guide

Carton Effects Guide

Choosing coatings and effects for folding cartons without losing print function.

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