01 HEAT-SEAL DECISION GUIDE
Seal-initiation temperature vs seal-strength target
Seal-initiation temperature and seal strength are connected, but they are not interchangeable. SIT is meaningful only when the threshold criterion and laboratory seal conditions are defined; seal strength is a measured response from a formed seal. Hot tack answers another question while the seal is still hot.
02 DECISION FRAME
A seal curve is a laboratory starting map—not a production setting guarantee
ASTM F2029 covers making laboratory heat seals and warns that laboratory and manufacturing equipment can differ in scale, sealing area and speed. ASTM F88 measures seal strength, while ASTM F1921 addresses hot seal strength before cooling. A buying comparison must preserve which outcome, specimen and method each reported value represents.
- A film enquiry claiming a lower seal-initiation temperature or wider seal window
- A packing-line issue involving weak seals, hot opening or inconsistent peel
- A material comparison where laboratory seal curves use different conditions
- That the first detectable seal provides the final strength or integrity the pack needs
- That jaw setpoint equals the temperature reached at the sealing interface
- That a laboratory seal curve validates production speed, contamination or package geometry
03 COMPARISON MAP
Use the right seal metric for the decision
Keep temperature threshold, cooled seal strength, hot tack and package integrity as related but distinct evidence.
Swipe or scroll horizontally to review every evidence column.
| Metric / evidence | Question it answers | Conditions to preserve | Do not substitute for |
|---|---|---|---|
| Seal-initiation temperature | At what stated condition does the seal reach an agreed threshold? | Threshold definition, structure, jaw system, temperature basis, dwell and pressure | Final seal strength, hot tack or production validation |
| Cooled seal strength | What force response and failure mode does the formed seal show after the stated conditioning? | ASTM F88 or other named method, specimen width, orientation, conditioning and technique | Seal continuity, leak integrity or hot-seal performance |
| Hot tack | How does the seal resist disruptive force before it has cooled? | ASTM F1921 or other named method, delay, specimen, jaws and seal conditions | Cooled peel strength or long-term package integrity |
| Seal window | Across which controlled conditions does the structure meet all agreed seal criteria? | Temperature series, dwell, pressure, line-relevant structure and each pass criterion | One isolated laboratory data point |
| Failure mode | How did the specimen separate or fail? | Peel, film tear, delamination, distortion or other agreed category | A force value reported without observation |
| Contamination tolerance | How does the intended fill or product residue affect sealing? | Representative contaminant, location, amount basis and trial method | A clean laboratory specimen |
| Production-line result | Can the roll form consistent seals at the intended operating conditions? | Jaw type, actual line settings, speed, cooling, fill, pack geometry and defects | A laboratory heat-seal curve |
04 SELECTION SEQUENCE
Move from a broad comparison to an approvable decision.
Define the required seal outcome
State whether the decision concerns initiation threshold, cooled strength, hot tack, easy-open behavior, integrity or a combination.
Compare one laboratory basis
Align specimen structure, preparation, jaw type, temperature basis, dwell, pressure, conditioning, test method and failure reporting.
Establish a production window
Use the laboratory curve only to plan the full-scale trial, then record line settings, pack conditions and finished-seal outcomes.
05 RFQ INPUTS
SIT, seal-strength and line-trial checklist
Request the complete test basis rather than a standalone temperature or force claim.
Open the RFQ brief builder ↗- 01
Exact sealant grade, full web structure, total thickness and sealing-surface orientation
- 02
Decision metric: SIT, cooled seal strength, hot tack, seal window, integrity or easy-open response
- 03
Threshold used to derive SIT and the reporting rule applied to the seal curve
- 04
Laboratory sealer type, jaw geometry or surface and temperature measurement basis
- 05
Dwell, pressure, specimen preparation, conditioning and time before strength testing
- 06
Seal-strength or hot-tack method, specimen orientation, fixture or technique and reporting unit
- 07
Failure mode, appearance, distortion, delamination and other acceptance observations
- 08
Representative product contamination, seal-area condition and package geometry
- 09
Production machine, jaw type, speed, settings, cooling and in-process inspection
- 10
Trial acceptance criteria, retain samples, responsible approver and commercial monitoring
06 EVIDENCE BOUNDARY
No universal SIT or seal-strength target is supplied
ASTM F2029, F88 and F1921 cover different parts of the heat-seal decision. This page does not reproduce their procedures and does not convert a laboratory curve into a line guarantee. The application owner and converter must define the threshold, methods, conditions and production acceptance window.
07 BUYER QUESTIONS
Resolve the assumptions that make quotes diverge.
01Is seal-initiation temperature the same as seal strength?+
No. SIT is a threshold derived under stated sealing and strength criteria. Seal strength is the measured response of a formed seal under a named test and conditioning basis.
02Does a lower laboratory SIT guarantee a faster packing line?+
No. Web construction, heat transfer, jaw type, dwell, pressure, cooling, contamination and machine geometry affect production. ASTM F2029 treats the laboratory curve as a starting point for full-scale conditions.
03When is hot tack relevant?+
Hot tack is relevant when the seal faces disruptive force before cooling, such as during form-fill operations. It is distinct from cooled seal strength and should use its own method and timing basis.
04Why should failure mode accompany a seal-strength value?+
The same force value can arise from different separation behavior, film deformation or delamination. Failure mode helps the buyer understand what the measurement represents and whether it fits the pack.