Polyken 345SW vs 3M 425 — Aluminum Foil Tape Comparison

Direct specification comparison for 3-mil aluminum foil tape — 3M 425 (3M #425) vs. Polyken 345SW speed tape — aircraft masking, vapor barriers, heat shielding, and HVAC sealing. AMS-T-23397B, MIL-T-23397, L-T-80, FAR 25.853(a).

Want the short version? Read 3M 425 vs Polyken 345SW: Foil Tape Compared →

Please Note: Always verify certified values against your applicable specification before qualifying any tape for production use.
Polyken 345SW Premium Self-Wound Aluminum Foil Tape Our Product

Polyken 345SW

Berry Global — Franklin, MA

Premium self-wound foil tape with heavy-duty dead soft aluminum backing and acrylic adhesive — no release liner. 68 oz/in adhesion to steel — roughly 45% above 3M 425's published 47 oz/in. Carries AMS-T-23397B, MIL-T-23397, L-T-80B, and Gulfstream GAMPS 4002 / GAT100BC approvals for aircraft sealing, masking, heat shielding, and vapor barrier applications.

3M 425 Aluminum Foil Tape
Available · 4–6 Week Lead

3M #425

3M Company — St. Paul, MN

Industry-standard 3-mil aluminum foil tape with transparent acrylic adhesive, widely used in HVAC, aerospace masking, heat reflection, and sealing. Documented low moisture vapor transmission and UL 746C / UL 723 Class "L" listings. Available from Skytapes on a 4–6 week lead time.

Both are dead soft aluminum foil tapes with acrylic adhesive for aircraft masking, vapor barriers, heat shielding, and HVAC sealing. Polyken 345SW delivers 68 oz/in published adhesion to steel vs. 3M 425's published 47 oz/in (different test methods) — plus a higher heat rating (350°F vs. 300°F) and broader aerospace specification coverage including AMS-T-23397B and Gulfstream approvals.

Overall comparison score

Polyken 345SW wins

7

categories

vs.

3M #425 wins

4

categories

Full specifications comparison

Property Polyken 345SW 3M #425 Advantage
Construction
Foil thickness 3.0 mil dead soft aluminum 2.8 mil dead soft aluminum (nominal 3 mil) Tie
Total tape thickness 5.0 mil (0.127 mm) 4.6 mil (0.12 mm) Polyken
Adhesive type Acrylic Transparent acrylic Tie
Liner None — self-wound (no liner waste) None — self-wound Tie
Physical Properties
Adhesion to steel 68 oz/in (7.44 N/cm) 47 oz/in (5.1 N/cm) +45% (diff. test)
Tensile strength 26 lb/in (45.53 N/cm) 28 lb/in (49 N/cm) 3M #425
Elongation 3% 6% 3M (more conformable)
High temp resistance 350°F (177°C) 300°F (149°C) long-term Polyken
Low temp resistance −40°F (−40°C) −65°F (−54°C) 3M (colder)
Water vapor transmission Not published 0.77 g/m²/24h (documented) 3M (documented)
Packaging & Value
Standard roll length 60 yd (stocked in 1" & 2" widths) 55 m (60 yd) Tie
Shelf life 24 months 24 months Tie
Availability at Skytapes Stocked 4–6 week lead time Polyken 345SW
Compliance
FAR 25.853(a) flammability Yes Yes Tie
Aerospace / military specs AMS-T-23397B, MIL-T-23397, L-T-80B, Gulfstream GAMPS 4002 / GAT100BC L-T-80C (can be certified), UL 746C, UL 723 Class "L" Polyken (broader aero)

Specifications & approvals

Polyken 345SW

✓FAR 25.853(a) flammability

✓SAE AMS-T-23397B (supersedes MIL-T-23397A & B)

✓L-T-80B

✓Gulfstream GAMPS 4002 & GAT100BC

✓Tested in accordance with UL 723

3M #425

✓FAR 25.853(a) flammability

✓UL 746C (File E 122798)

✓UL 723 Class "L" low flammability (File R 7311)

✓Can be certified to L-T-80C

✗AMS-T-23397B / Gulfstream approvals not listed

Where each product wins

Polyken 345SW advantages

  • Published adhesion ~45% higher — 68 vs. 47 oz/in (different test methods)
  • Higher heat rating: 350°F vs. 300°F long-term for 3M 425
  • Thicker total tape: 5.0 mil vs. 4.6 mil
  • Broader aerospace coverage: AMS-T-23397B, MIL-T-23397, Gulfstream GAMPS 4002 / GAT100BC
  • Self-wound construction — no liner waste
  • Excellent solvent resistance for paint stripping & electroplating masking
  • Stocked at Skytapes — 3M 425 is a 4–6 week lead

3M #425 advantages

  • Wider cold temperature range — rated to −65°F vs. −40°F for Polyken
  • Slightly higher tensile strength: 28 vs. 26 lb/in
  • Higher elongation (6% vs. 3%) for better conformability over contours
  • Documented low moisture vapor transmission rate as a sealant
  • UL 746C and explicit UL 723 Class "L" file listings

Which tape to specify

If your requirement is… Specify Reason
Maximum peel adhesion to metal surfaces Polyken 345SW 68 oz/in vs. 47 oz/in published for 3M 425 (different test methods)
High-temperature duct, heat shielding & "hot spot" applications Polyken 345SW Rated to 350°F vs. 300°F long-term for 3M 425
AMS-T-23397B / MIL-T-23397 or Gulfstream-approved tape Polyken 345SW Explicitly lists these specs; 3M 425 does not
Paint stripping & electroplating masking Polyken 345SW Solvent-resistant acrylic adhesive with clean removal
Needed now — no lead time Polyken 345SW Polyken 345SW stocked; 3M 425 4–6 week lead time
Extreme cold applications (below −40°F) 3M #425 3M 425 rated to −65°F; Polyken rated to −40°F
Moisture / vapor barrier with documented WVT data 3M #425 3M publishes a 0.77 g/m²/24h transmission rate; Polyken does not
Conformability over tight irregular contours 3M #425 Higher elongation (6% vs. 3%)

Polyken 345SW specifications from Berry Global TDS (rev. 4/11/18) and Product Information Sheet. 3M 425 specifications from 3M Technical Data Sheet (rev. May 2022). 3M lists its values as "representative or typical" and not for specification purposes; Polyken adhesion/tensile values are per PSTC test methods while 3M values are per ASTM — verify certified values against your applicable specification before use.

Prefer a plain-English summary? Read the article: 3M 425 vs Polyken 345SW →