By John Keema · Updated October 13, 2026
Use an impulse sealer for batch work and frequent size changes, constant heat when you want to hold a set temperature, or a continuous band sealer for steady runs. Match the specific machine to the pouch’s full seal length, laminate and combined wall thickness, then confirm settings with a filled-pouch trial.
CPP makes custom printed stand-up and flat pouches; we do not sell sealers. The film specifications below give you reference values to take to an equipment supplier.
CPP pouch specs that matter for heat sealing
All six CPP materials are three-layer laminates with a polyethylene-based interior sealant. Each material specification lists a seal temperature range of 250–350 °F (120–180 °C). The inner sealant is the layer that bonds the two pouch walls.
| Material | Layers: exterior / print / sealant | Thickness per wall | Listed seal temperature | Listed seal strength |
|---|---|---|---|---|
| White Matte BOPP | 1.3 mil matte BOPP / 48 ga PET / 3.0 mil white EVOH PE | 4.9 mil (about 124.5 µm) | 250–350 °F (120–180 °C) |
≥9 lb/in |
| White Gloss PET | 1.2 mil gloss PET / 48 ga PET / 3.0 mil white EVOH PE | 4.8 mil (about 122 µm) | 250–350 °F (120–180 °C) |
≥9 lb/in |
| Clear Matte BOPP | 1.3 mil matte BOPP / 48 ga PET / 3.0 mil clear EVOH PE | 4.9 mil (about 124.5 µm) | 250–350 °F (120–180 °C) |
≥9 lb/in |
| Clear Gloss PET | 1.2 mil gloss PET / 48 ga PET / 3.0 mil clear EVOH PE | 4.8 mil (about 122 µm) | 250–350 °F (120–180 °C) |
≥9 lb/in |
| Metallic Matte BOPP | 1.3 mil matte BOPP / 48 ga metallized PET / 3.0 mil clear mLLDPE | 4.9 mil (about 124.5 µm) | 250–350 °F (120–180 °C) |
≥7 lb/in |
| Metallic Gloss PET | 1.2 mil gloss PET / 48 ga metallized PET / 3.0 mil clear mLLDPE | 4.8 mil (about 122 µm) | 250–350 °F (120–180 °C) |
≥7 lb/in |
Source: CPP materials and finishes comparison guide (PDF) and the individual specification sheets, CPP edition 1.0, September 2026. Seal strength is listed self-to-self; the sheets do not identify a test method.
CPP has not supplied confirmed trial data for customer top seals. Confirm the starting settings and usable seal zone with CPP and your equipment supplier, then test your actual filled pouch. A machine’s displayed temperature is not necessarily the temperature at the seal interface.
What these numbers mean for your sealer
- Thickness through the jaws: Two walls total about 9.6–9.8 mil (244–249 µm). With the listed ±10% tolerance, the upper end is about 10.8 mil. Ask whether a machine’s maximum thickness rating is per wall or combined.
- Temperature: Bring the listed range to your equipment supplier to establish an approved trial baseline. An impulse dial normally controls time, not degrees.
- Metallic needs its own trial: Metallic options use mLLDPE and list ≥7 lb/in, compared with ≥9 lb/in for white and clear. Do not reuse settings proven on a different laminate.
- Storage: CPP lists 12 months from delivery, at 50–80 °F (10–26 °C) and 30–70% relative humidity. This is guidance for storing the pouch material, not the shelf life of its contents.
What “Mylar bag” means for CPP pouches
The sealant layer, not the “Mylar” label, determines how a pouch seals. Mylar® is a brand of polyester (PET) film; “Mylar bag” is also used loosely for metallic or multilayer pouches.
- Every CPP material includes PET film. Gloss options have a PET exterior and PET print layer. Matte options pair a BOPP exterior with a PET print layer.
- CPP metallic pouches use metallized PET, not foil. Their metallic appearance comes from the metallized PET print layer.
- The inside is polyethylene-based. White and clear use EVOH PE; metallic uses mLLDPE.
For bags from another supplier, ask for the layer structure, total thickness per wall and recommended sealing guidance.
Impulse vs. constant-heat vs. band sealers
Pick the type by workflow, then confirm that the specific model handles your pouch’s thickness, seal length and laminate.
| Compare | Impulse sealer | Constant-heat sealer: direct heat / hot jaw | Continuous band sealer |
|---|---|---|---|
| How it heats | An element heats during a timed pulse, then the seal cools under pressure. | Jaws or bars stay at a set temperature. | Moving bands carry the pouch top through a heated section. |
| What you set | Heat time; cooling time on some models. | Temperature; dwell and pressure on some models. | Temperature and conveyor speed. |
| Best fit | Batch work, small runs and frequent size changes. | Batch work where you want to read and hold a temperature. | Steady runs of one pouch size and fill. |
| Watch for | Dial numbers are not temperatures. Check the combined-thickness rating. | Warm-up time; jaws remain hot between seals. | Pouch support, fill weight, conveyor height and changeovers. |
| Manufacturer documentation | Fujiimpulse FS series; Sealer Sales instructions (PDF) | AIE constant-heat CH series | Audion D 547 AVTS |
These are documentation examples, not sealer models CPP has tested or endorsed for its finished pouches.
Shortlist a model in five checks
- Seal length: Measure across the top of your widest pouch. A jaw must cover it in one closure; a band sealer must accommodate the full opening in its pass.
- Thickness: Confirm capacity for two pouch walls, including the material’s tolerance.
- Laminate compatibility: Give the supplier the film structure and listed temperature range. Ask for suitable starting settings and a trial.
- Workflow: Compare batch handling with continuous feeding, including size changes and warm-up.
- Support: Plan how filled pouches stay level and supported before, during and after sealing.
Where to place the seal on a zippered pouch
Place the heat seal above the tear notches and above the zipper. The zipper recloses the pouch after first opening; the top heat seal keeps it closed until then. CPP’s standard zipper is not a tamper-evident or child-resistant closure.
- Keep the jaws off the zipper so they do not crush or melt its track.
- Leave the zipper usable after tearing. The notch should let the customer remove the sealed strip.
- Keep the seal zone clean. Dust, crumbs, powder and oil can interrupt the seal.
Use the approved dieline for your chosen format and size, and confirm the usable header with CPP. There is no confirmed universal seal offset in this guide. Without a zipper, seal the full top opening and keep any tear notches below the seal.
Can you use a hair straightener, iron or vacuum sealer?
Hair straightener or clothes iron
These do not provide the controlled pressure, timing and cooling of a purpose-built pouch sealer. A temperature display alone does not establish suitability for the laminate. For products you sell, choose equipment rated for the material and document the trial.
Household vacuum sealer
Check the manufacturer’s compatibility guidance. A machine designed for its own vacuum bags may not suit your laminate or combined thickness. If it has an approved seal-only mode for the material, test that mode with your actual pouch; do not assume compatibility.
How to run a controlled seal trial
Find repeatable settings using real pouches, real product and the machine you plan to run.
- Gather starting points. Give the equipment supplier CPP’s film specifications and follow the machine’s operating instructions.
- Fill as you will in production. Use the same product, fill weight and filling method so trapped air and contamination appear in the trial.
- Set an approved baseline. Use the equipment and pouch suppliers’ guidance. Record every available control; an impulse dial sets heat time, not temperature.
- Change one variable at a time. Adjust temperature, heat time, cooling time, pressure or conveyor speed while keeping the others fixed.
- Let the seal cool. Follow the machine’s instructions for cooling under pressure before releasing or handling it.
- Inspect the full width. Look for channels, wrinkles, trapped product, burning, shrinkage and incomplete bonding.
- Repeat at startup and during a run. A batch of 10 pouches per setting can help compare results; it is an example, not a validated sampling or acceptance plan.
- Record the result. Note the pouch material, size and lot, product, fill weight, machine, settings, operator and observations.
A packaging lab can measure seal strength using ASTM F88/F88M. Confirm the test method and conditions before comparing a result with CPP’s listed values. Peel strength alone does not establish leak integrity or product shelf life.
Record the wider package checks with CPP’s custom pouch testing checklist.
Troubleshooting common seal problems
Most seal failures involve heat, pressure, alignment or contamination. Change one thing at a time and retest.
| Symptom | Likely causes | Try first |
|---|---|---|
| Open spots or incomplete seal | Insufficient heat or time; uneven pressure; misalignment; worn element or pad. | Check alignment, element and pad. Then adjust within the supplier-approved trial settings. |
| Wrinkles or channels | Uneven feeding, trapped air or uneven pressure along the bar. | Flatten and support the top, then check pressure across the full seal length. |
| Burned, shrunk or distorted film | Excessive heat or dwell time; insufficient cooling. | Reduce heat or time and check cooling. Do not keep increasing heat. |
| Product caught in the seal | Overfilling, dust, powder, oil or unsettled product. | Fix filling first: leave enough headspace and keep the seal zone clean. |
| Seals peel easily or vary | Contamination; inconsistent timing or pressure; too little cooling; incomplete warm-up. | Compare operators and run time. Let constant-heat equipment reach its operating condition. |
If the problem persists, share the trial records with the equipment supplier and CPP.
Checklist to bring to your sealer supplier
Give the supplier these details and ask for written confirmation that the machine fits.
0 of 9 items checked
Ask for a witnessed or documented trial using your actual pouches and product. Contact CPP about sample availability for your trial.
Heat sealer FAQs
What temperature should I use to seal Mylar bags?
CPP’s six film specifications list 250–350 °F (120–180 °C). Use that as a material reference, not a confirmed finished-pouch recipe. Get starting settings from the pouch and equipment suppliers, then test your filled pouch. Other suppliers’ bags may differ.
What is the best heat sealer for Mylar bags?
Choose by pouch and workflow: impulse for batch work, constant-heat to hold a set temperature, or band for continuous runs. Confirm full seal length, laminate compatibility and combined wall thickness, then run a trial.
Can an impulse sealer seal thick Mylar bags?
Yes, if the manufacturer rates the model for the laminate and combined thickness. CPP film is nominally 4.8–4.9 mil per wall, or 9.6–9.8 mil for two walls, before tolerance. Confirm how the rating is stated and test the actual pouch.
Do I still need to heat seal a pouch that has a zipper?
Yes. The zipper recloses the pouch after first opening; the top heat seal keeps it closed until then. Place the seal above the tear notches and zipper, within the confirmed usable header.
Should I double seal Mylar bags?
It is optional and should be validated in your trial. A second parallel seal needs enough usable header space and does not fix contamination, wrinkles or unsuitable settings.
Are CPP’s metallic pouches foil?
No. They use metallized PET, not aluminum foil. The film sheets list oxygen transmission limits of ≤0.03 versus ≤0.06 cm³/100 in²/24 hr for white and clear, and water-vapor limits of ≤0.13 versus ≤0.063 g/100 in²/24 hr. These are film reference values under the stated test conditions, not a finished-package shelf-life claim.
Can one heat sealer handle different pouch sizes and materials?
Often, if it accommodates each pouch’s seal length, thickness and laminate. Prove and record settings separately for each combination. Metallic pouches need their own trial.
Does a wider seal mean a stronger seal?
Not by itself. Width cannot compensate for contamination, wrinkles, poor alignment or unsuitable settings. Confirm both seal strength and package integrity using appropriate tests.
Choose your pouch, then test the sealed package
Stand-up pouches use a bottom gusset for shelf presentation; flat pouches suit samples, single servings and refills. Choose your size, material, zipper and tear notches in the configurator and get a live quote. Orders start at 100 pouches.
Sources and further reading
- CPP materials and finishes and comparison guide (PDF): layer structures, thickness, seal temperature and self-to-self strength.
- CPP individual material specifications (PDF): White Matte BOPP, White Gloss PET, Clear Matte BOPP, Clear Gloss PET, Metallic Matte BOPP, Metallic Gloss PET.
- Mylar Specialty Films: polyester film.
- Fuji-Sotex: Fujiimpulse FS series: timed heating and cooling under pressure.
- Sealer Sales: impulse hand-sealer instructions (PDF): timing controls and cooling.
- American International Electric: CH series: constant-heat equipment.
- Audion: D 547 AVTS: band-sealing controls and pouch support.
- ASTM F88/F88M-23: laboratory seal-strength test method. The CPP sheets do not identify this as the method used for their listed values.
