Handheld inkjet printers for batch and expiry codes: what to test before you buy

A handheld inkjet printer can put a clean batch number and expiry date on cartons, pouches and labels. It does that well only when the ink suits your exact pack surface. So before you buy one, print your real code on your real packs. Time how long the ink takes to stop smudging, rub it, tape-test it, and work out what each good code costs you.

A demo on the seller's clean white carton proves very little. Your pouch has a different skin.

We make plastic films and tapes at Jagannath Polymers, and labels are made by Jagannath Labels, our group's label company. I am not recommending any printer brand here. My aim is to help you test whatever printer you are offered, so that you buy once.

What a handheld coder does well, and where it struggles

A handheld inkjet is a small printer that you roll across the pack by hand. Many of the ones sold for coding use a cartridge with rows of tiny nozzles that fire drops of ink. One pass can print a line or two of text, a date, a small logo or a simple code.

It suits these jobs:

1. Small batches and many products, where a coder fixed on a conveyor would stand idle.
2. Cartons, shipper boxes and flat pouches that sit still on a table.
3. A young business, before volumes justify a coder on the line.

It struggles with these:

1. Round bottles, and soft pouches that flex under the printer's roller.
2. Long shifts, because a hand gets tired and codes start to slant.
3. Very small packs that need tiny, crisp characters.
4. Barcodes that a buyer will grade, because hand speed can stretch the bars.

That last point matters more than it looks. With a handheld, the operator is part of the printer.

So we would train two people on it, not one.

Start with your pack, not the printer

Coding inks come in two broad families. Water-based inks soak into paper and board. Solvent-based inks dry by evaporation and are made to hold on surfaces that soak up nothing, such as film, foil, glass and metal.

Here is how I would think about common packs.

One insider point, because we sit on the film side of this. Film meant for printing is normally treated on the print side so that ink can grip it. A plain film or pouch whose outer side was never meant to carry print is the hardest surface on this list. Polythene is also one of the lowest-energy surfaces you can label or print, as our lesson on label adhesives shows with 3M's figures.

So ask your pouch supplier which side was treated before you blame the printer.

The rules your code must meet in India

For prepackaged food, the FSSAI Labelling and Display Regulations, 2020 (compendium Version VII, dated 3 April 2025) say what the code must carry and how it must look.

1. A batch number, code number or lot number must be on the label (regulation 5(9)).
2. The date of manufacture or packing and the expiry or use by date must both be declared, grouped together at one place. Best before may be added (regulation 5(10)).
3. For a shelf life of up to 3 months, dates go as DD/MM/YY. Above 3 months, month and year are enough, with the month in capital letters and at least its first three letters. DD/MM/YY is allowed there too.
4. Everything on the label must be clear, indelible and readily legible under normal conditions (regulation 4(7)). A code that smudges in the carton fails this.
5. Information that is not pre-printed, like your coder's block, may be grouped in one place of its own, apart from the pre-printed information (regulation 6(1)).
6. Table I in regulation 6(3) sets the smallest letter height by the area of the principal display panel: 1 mm up to 200 cm², 2 mm up to 500 cm², 3 mm up to 2,500 cm², and 6 mm above that. For the expiry, best before or use by date, net weight, price and consumer care details, it points to the Legal Metrology rules instead.

Measure your printed code with a steel ruler. I would not guess this one.

Then check both sets of rules with your food safety consultant, because your product category may add its own.

There is one more rule people miss. The FSSAI Packaging Regulations, 2018 (compendium dated 1 June 2022) say in regulation 3(9) that printing inks used on food packages shall conform to IS 15495. The next clause says the printed surface shall not come into direct contact with the food. So code only the outside, and ask the ink supplier for a written statement on IS 15495 for the exact ink you will buy.

One hour with a demo printer: the test

Ask the seller for a demo unit, or a demo at your site with your own packs. This is the test we would run if we were buying one for our own dispatch.

Most of it takes an hour. Only the rub check waits until the next day.

1. Collect 20 of each real pack from your stock: cartons, pouches, labels. Take the dusty and slightly oily ones as well as fresh ones.
2. Print your real code at its real height, for example a batch line, a packed date and a use by date.
3. Drying: rub one code with your thumb 1 second after printing, the next after 3 seconds, then 5, 10 and 30. Write down the first time the code does not smear. That is the real dry time on that pack.
4. Rubbing: the next day, rub a code 10 times with a thumb. If your product is oily or wet, rub with an oily or damp finger as well.
5. Tape: press clear packing tape firmly over a code and pull it off fast. Ink on the tape means the ink is not holding.
6. Cold and damp: if packs come out of a cold room, code one cold pack and one dry pack and compare them.
7. Reading: ask someone who has not seen the code to read it to you at arm's length. If there is a barcode, scan it with the scanner your buyer uses.
8. Idle time: leave the printer unused, uncapped, for your normal tea or lunch break, and print again. Count the patchy codes before it prints clean.
9. Two operators: let two people print 50 codes each, and check how straight and how well placed the codes are.

Step 8 is the one a seller rarely shows. We sell air cushion machines, and I tell buyers the same thing there. The film you use up every day matters more than the machine you buy once. A coder works the same way, with ink in place of film.

The nozzles of a solvent cartridge can dry out when left open. Some ink goes into wiping and purging every morning and after every break, and that ink is part of your cost.

The true cost per code

Do not compare printers on the cartridge price alone. Compare the cost of one good code.

I would do this sum before I signed anything.

Cost per code = (cartridges + cleaning supplies) ÷ codes that pass

You can measure the bottom half of that sum yourself.

1. Weigh a new cartridge on a jeweller's scale that reads to 0.01 g.
2. Print 200 of your real codes.
3. Weigh it again. The difference divided by 200 is the ink in one code.
4. Run one full cartridge to empty in normal work, counting codes and rejects, to confirm the estimate.

Here is a made-up example, only to show the sum. If 200 codes use 1 g of ink, each code takes 5 mg. A bold font, a second line or taller letters raise that. Then take away the ink lost in purging and wiping, and the packs you reject and recode.

Three things move the cost more than people expect.

1. What you print. Every extra character uses ink, so "PKD", "USE BY" and a second line cost more than a short batch line.
2. Low use. A cartridge opened and then left for weeks can dry out before it is empty. Ask the seller how long a cartridge lasts once it is opened.
3. Rejects. A smudged code means a relabelled or wasted pack, which costs far more than the ink.

Handheld, a fixed coder or a printed label?

A handheld is often where coding starts, not where it ends. I would look at other routes when:

1. One person spends most of the shift coding.
2. Codes wander, and packs get rejected for position or legibility.
3. A buyer asks for a barcode with a print quality grade.
4. Packs already move on a conveyor or a filling machine.

Two common next steps are a coder fixed on the line, or pre-printed labels where only the batch and dates are added by a thermal transfer printer. Our lesson on direct thermal or thermal transfer covers that route. Whichever you choose, the code has to lead back to your records, as our batch traceability starter system explains.

Mistakes I would avoid

1. Buying after a demo on the seller's own carton.
2. Coding across a varnished or heavily printed area when a plain panel is free.
3. Using one ink for cartons and pouches without testing it on both.
4. Letting the code shrink below the legal minimum height to save ink.
5. Forgetting to cap the cartridge when the shift ends.

I will admit one limit of this whole method. A one-hour test cannot show what happens after six months in a hot godown. Keep a few coded packs from your test, and look at them again at the end of their shelf life.

If the inkjet keeps failing on your film, a printed label may be the simpler answer. Tell us your pack and the code you need through the contact page, and we will suggest what we would try first.