What Your Security Seal Is Really Made Of

Posted on by Barnes

Material Matters: What Your Security Seal Is Really Made Of

When you’re shopping for security seals, it often starts with the usual question: “Plastic or metal?” But let’s be real—there’s way more going on beneath the surface.

The materials behind modern high-security seals aren’t just picked at random. They’re chosen based on a smart mix of strength, flexibility, tamper visibility, and durability. And if you’re working with regulations like ISO 17712, choosing the right material can make or break your compliance.

So let’s break it down. No fluff. Just what you need to know.

Not Just Plastic: Polymers with Purpose

Plastic isn’t just plastic. Different types serve different purposes, and they all have their sweet spots.

Polypropylene (PP)

  • Why it’s popular: Lightweight, affordable, resists chemicals, and shows clear tamper evidence (it turns white when stressed).

  • Where it’s used: Pull-tight seals, fixed-length seals, outer layers of bolt seals.

  • Watch out for: Lower heat and tensile strength—keep it away from extreme conditions.

Nylon (PA)

  • Why it’s better: Super tough, handles abrasion well, doesn’t mind the heat.

  • Where it’s used: Stronger pull-tight seals, sometimes in cable seal mechanisms.

  • Pro tip: When you need something a little more rugged than PP, nylon steps up.

Polycarbonate (PC)

  • Why it’s clever: Transparent, tough as nails, resists heat.

  • Where it’s used: Meter seals, any seal where you want visibility into the internal mechanism.

  • Bonus: Makes tampering easier to spot, especially for regulatory checks.

ABS (Acrylonitrile Butadiene Styrene)

  • Why it’s tough: High impact resistance, customizable, tamper-evident when it breaks.

  • Where it’s used: Bolt seal casings, some chunky fixed-length seals.

  • Fun fact: It snaps cleanly when messed with, which is great for spotting tampering.

Metal Matters: The Backbone of High-Security Seals

When brute force resistance is non-negotiable, metal steps in.

Carbon Steel

  • Why it rules: Strong, hard, tough to cut. Often zinc-coated to fight rust.

  • Where it’s used: Bolt seals, cable cores.

  • Ideal for: Meeting ISO 17712’s high-security standards.

Stainless Steel

  • Why it’s a fave: Rust-resistant, hygienic, can handle wide temp swings.

  • Where it’s used: Internal parts, seals exposed to harsh conditions (think: food, pharma, marine).

  • Good to know: If your seal’s going on a long trip or getting wet—this is your guy.

Aluminum Alloys

  • Why it’s handy: Lightweight, easy to color, decent corrosion resistance.

  • Where it’s used: Cable seal bodies, tamper-evident markings.

  • Heads-up: The steel does the heavy lifting—the aluminum is mostly for looks and function.

Zinc Alloys

  • Why it’s smart: Great for complex shapes, decent strength, corrosion resistant.

  • Where it’s used: Padlock seal bodies, precision locking parts.

  • Why it matters: Lets you create tricky locking mechanisms without bulking up.

Mix It Up: Hybrid Designs for Extra Punch

The strongest seals blend both worlds—plastic and metal.

  • Bolt seals: High-carbon steel pins wrapped in ABS or PP. You get strength and color coding + tamper-evidence.

  • Cable seals: Steel cable for resistance, aluminum or zinc for easy marking and branding.

  • Added extras: Sometimes plastic coatings go over metal parts to help with grip, durability, or just making it easier to spot tampering.

What Else Should You Look For?

Materials are more than just strong. They’ve got to perform under pressure.

  • UV Resistance: If your seal’s outside in the sun, it better not crumble. Additives help plastic stand up to UV rays.

  • Extreme Temps: Global transit means crazy hot and icy cold. Make sure your materials don’t crack or warp.

  • Chemical Exposure: Industrial environments can be messy. Seals must hold their own if they come into contact with solvents or grease.

TL;DR: It’s Not Just “Plastic or Metal”

Knowing what your security seal is made of helps you choose smarter. Because the right material means:

  • Fewer breakages.

  • Better tamper detection.

  • Easier compliance.

  • And seals that just last longer.

So don’t just go for the cheapest option—or whatever your supplier suggests off-hand. Ask what it’s made of. Better yet, talk to a seal manufacturer (like Acme Seals) that knows their materials inside out.

Need Help Choosing the Right Material for Your Seal?

Whether it’s keeping your container secure during a 5,000 km shipment or locking down critical assets at a remote site, the right material makes all the difference. Let’s chat. Our experts at Acme Seals are here to help you make the smartest, safest pick for your operation.