How to Tell If Your Toy Is Silicone or PTE Using the Seam Line

Many products on the market are made from PTE yet claim to be silicone. If you've ever wondered how to verify what you're actually holding, here's a method that professionals in the industry use — and it starts with something called the seam line.

First: Both Silicone and PTE Have Seam Lines

Let's clear up a common misconception. Both silicone and PTE (a thermoplastic elastomer blend often used as a cheaper silicone substitute) are made using molds — and both will have a seam line where the two mold halves meet. So simply having a seam line doesn't tell you anything about the material.

What matters is how that seam line was treated after manufacturing — and that's where things get interesting.

Step 1: Look for the Seam Line — Or the Lack of One

Flip the product over and examine the base, especially around the suction cup edge. This is where the mold seam is most visible.

↑ The seam line runs along the edge of the suction cup base — this is the first place to check.

• Silicone seam lines can only be removed mechanically — trimmed with a knife or scissors. This takes skill and time, and a faint line often remains.
• PTE seam lines can be removed with heat — a flame or a hot iron causes the material to shrink and the seam line simply melts away and disappears.

So here's the first clue: if a product has absolutely no visible seam line and the surface looks perfectly smooth everywhere — that's actually a red flag for PTE. Real silicone almost always retains at least a faint trace of the seam, because you can't melt it away.

Step 2: The Fire Test — The Definitive Method

But what if the PTE product wasn't heat-treated? What if it still has a seam line, just like a silicone product? How do you tell them apart then?

This is where the fire test comes in. It's simple, fast, and definitive.

1. Find the seam line on the product (usually along the base or shaft)
2. Hold a lighter flame briefly to the seam line — just a second or two
3. Watch what happens:

• 🔥 PTE: The seam line will shrink and disappear as the material contracts from the heat. The surface may also become slightly shiny or deformed around the area.
• ⚫ Silicone: The seam line stays exactly where it is. The surface may turn black or leave a carbon residue, but it won't shrink, melt, or deform. Real platinum-cured silicone is heat-stable and simply chars rather than melting.

Why This Matters

This isn't just a fun party trick. The difference between silicone and PTE has real implications:

• Porosity: PTE is porous, meaning bacteria can hide in microscopic surface pores even after cleaning. Silicone is non-porous.
• Longevity: PTE can degrade over time, becoming sticky or cracking. Silicone lasts for years with proper care.
• Body safety: Platinum-cured silicone is inert and hypoallergenic. PTE formulations vary widely in quality and safety.

A Note on Testing

We recommend doing the fire test on a small, inconspicuous area — like the very edge of the suction cup base — rather than on a visible surface. And of course, do it safely: hold the product with a cloth or glove, keep the flame brief, and do it in a ventilated area.

Want to Put It to the Test?

If you own one of our products, we genuinely invite you to try it. Hold a flame to the seam line and see what happens. The line won't disappear — it'll just char slightly, exactly as real platinum-cured silicone should. We're confident enough in our materials to say: test us.

Curious about how our products are made or have questions about materials? We love talking craft — reach out anytime at realtouchlab.com.