Choose a hot melt adhesive for carton sealing by checking the actual bonding surface and the delay from glue application to flap compression. Then check the time under compression and the temperatures the sealed case will encounter.
A grade that looks suitable on a data sheet can still fail on recycled board, a coated carton, or a faster sealer. Use your production board and machine for the final decision. Good Adhesive’s packaging adhesive range provides starting grades for these trials.
What surface will the adhesive actually touch?
Test the surface beneath the glue bead. An uncoated corrugated flap, a liner with high recycled content, and a film-laminated retail carton present different bonding surfaces. A change of board supplier or coating can change the result even when the case design stays the same.
Collect samples from the production lot and mark where the bead lands. Note dust, print, varnish, film, and any differences between the top and bottom flaps. If several board stocks run on one sealer, include each in the trial.
Does the open time fit your application-to-compression delay?
The adhesive must remain able to bond until the flaps meet under compression. Measure the interval from bead application to contact across normal line speeds and case spacing. Record how your line handles stops and restarts separately. Compare the measured interval with the candidate grade’s open time under your operating conditions.
An adhesive that sets before the second flap touches it may stay on the first flap and leave a weak seal. Smithers explains the difference between open time and setting time; the two measurements describe different parts of the sealing process.
Will the seal hold when compression ends?
The bond needs enough early strength to resist flap spring-back when the compression section releases the case. Record the time under compression, then inspect the bead on cases that reopen immediately. A rounded bead or patchy transfer to the second flap points to a different problem than adhesive that transfers well but remains too soft at release.
Check bead position, application amount, nozzle condition, and actual temperature at the applicator before switching grades. If those are stable, trial a grade whose setting behavior matches the available compression time.
Should you trial an EVA or an APAO grade first?
For uncoated corrugated cases, trial an EVA carton grade first; for film-laminated cartons, include an APAO grade formulated for coated board. Good Adhesive lists EVA YD-5158 for general carton sealing and EVA YD-5313 for faster lines. Its APAO YD-5100 is another candidate for standard corrugated board. For laminated board, start with its YD-5289 APAO grade.
These are application matches, not guarantees for every liner, coating, or sealer. Compare candidate grades on the same board at the same machine settings. Ask for the current technical data sheet before setting a production temperature or approving a grade.
Can the bond survive storage and transit?
Test the sealed case at the coldest and warmest conditions it will actually face. A case that passes immediately after sealing may behave differently in a cold warehouse, a hot trailer, or after a board change. Include the packed case’s weight and handling conditions in the test.
Do not use a softening-point figure alone as proof of package performance. The outcome depends on the adhesive, the board surface, the bond geometry, and how the case is handled after sealing.
What does a useful line trial record?
A useful trial records the process conditions alongside the bond result. Keep the board lot, case design, line speed, applicator temperature, bead placement and amount, application-to-compression delay, and compression time for each candidate. Inspect cases immediately after release and again after the planned storage or distribution condition.
On uncoated corrugated board, fiber tear can be a helpful sign of a strong bond. Also record whether adhesive releases cleanly from one flap or splits within the glue layer. Those failure patterns help the supplier separate wetting, compression, and setting-speed problems. On coated board, use the agreed package performance test rather than fiber tear alone.
What should you send when requesting a matching grade?
Send the supplier a sample of each bonding surface and the timing measured on your sealer. Include the current adhesive grade, photos of any open cases and glue beads, the machine type, application temperature, case weight, and the storage and shipping temperature range. These details make a sample comparison more useful than a request for “stronger glue.”
