Is Silicone Plastic? A Buyer’s Lesson on Material Verification

Let me state something that might sound obvious: searching for “plastic little” is not a procurement strategy.

I am an office administrator for a 38-person industrial company. I manage about $55,000 in annual MRO and material orders across seven vendors. When I took over purchasing in 2020, I thought the hard part was finding the best price. It wasn’t. The hard part was knowing what I was actually buying.

I now believe that understanding the material before you order is the single highest-leverage step in the entire purchasing process. Not delivery speed. Not cost per part. Those matter, but if the material is wrong, none of the rest matters.

Why “Plastic Little” Is Not a Specification

When someone walks over and says “we need a plastic little thing for this bracket,” I used to write it down and try to find something. Now I stop. “Plastic little” could mean polypropylene, polycarbonate, ABS, or a urethane casting. Each one behaves differently. Each one costs differently.

That’s not a criticism of the people making the request. It’s the system’s fault. We expect buyers to translate vague phrases into technical specifications without giving them the tools. The fix is simple: slow down and name the material.

Is Silicone Plastic? The Answer Affects Your Order

A few months ago, we needed silicone for molds. That request led me to a question I should have asked earlier: is silicone plastic?

Short answer: no. Silicone is a synthetic elastomer. It is a polymer, but it does not sit in the same family as the thermoplastics we usually order. It handles heat and flexibility differently than most plastics. It is often the right material for molds and gaskets. But it is not plastic.

Why does this matter for procurement? Because the material determines the mold’s behavior. A plastic that melts under heat or warps during curing will ruin your production run. Silicone for molds is chosen for release properties and temperature tolerance. If you accidentally order a plastic-based compound, you will find out at the worst possible time.

The question isn’t only “is silicone plastic?” The question is “what environment will this part live in?” That’s the starting point for every material decision I make now.

A Real Order: When I Ignored the Spec Sheet

I still kick myself for this one. We needed a flexible mold for a prototype. The jsp store had silicone mold rubber in two hardness options. The product page said: “Select lower Shore for flexible detail, higher Shore for tear resistance.”

Did I read the instruction? Honestly? No. I selected the lower-cost option and submitted the order. A week later, the mold tore when we pulled the first part.

The replacement compound cost maybe $65. I don’t remember the exact figure—$70? Doesn’t matter. The real cost was the delay. We had promised a sample to a customer, and the prototype ended up a week late. I had to explain to my VP why a “simple supply order” had a cascade of consequences. The most frustrating part: this was completely avoidable.

I only believed the warning after ignoring it. That’s the reverse validation no one wants.

How jsp Products Changed My Buying Process

When I finally stopped googling vague phrases and started using the jsp store with specific material requirements, everything changed. The jsp products catalog lists items by material property, not just by product name. Polyethylene, polypropylene, polyurethane, silicone. Each has a separate section. That structure forced me to learn the difference.

One thing I appreciate about jsp products: they don’t let you hide behind a vague description. You have to pick a resin type. You have to pick a hardness or thickness. That friction is annoying at first. It is also the whole point.

I don’t buy from jsp because they have every material. I buy because the store makes me verify the material before I spend money. The verification step is what prevents the $600 re-order that gets charged to my department’s budget.

What I Check Before Clicking Order

I run through a short checklist now. It is not fancy, but it works.

• What material did the original part use? If I’m replacing a component, I try to match the resin, not just the shape.
• What environment will the part face? Heat, chemicals, UV, mechanical load? That rules out materials immediately.
• What does the datasheet say? A spec sheet is not a suggestion. It is a contract.
• Is this the right product class? Is silicone actually plastic? No. Is polyurethane plastic? Kind of, but it behaves differently from most thermoplastics. Get the category right.

Honestly, this takes five minutes. The last time I skipped it, I spent a week dealing with the mistake. Not ideal. Workable, but not ideal.

Fast Is Another Word for Preventable Rework

The objection I hear most: “But we need it fast.” I get it. I used to rush orders too. But a rushed order with a vague description gets you a wrong part, and the correction path is almost always longer than the time you saved.

One order in 2023 proved this to me. We were out of a replacement part, and the internal request said “clear plastic.” I ordered polycarbonate because I assumed clear meant tough. It turned out the application needed acrylic for optical clarity. The difference? Polycarbonate has good impact resistance, but acrylic has better optical clarity. Our customer noticed the difference in the window prototype. We reordered the correct acrylic from the jsp store and paid for both orders. That’s the kind of lesson that stays with you.

The question we should have asked at the beginning: what is the part supposed to do? Not “what does it look like?”

The Bottom Line: Verify Before You Spend

I’m not going to soften this. Five minutes of verification beats five days of correction. That’s the opinion I’ve formed after five years of sourcing materials, managing vendor relationships, and absorbing the occasional embarrassing mistake.

If you’re buying from a material supplier and you’re not sure whether silicone is plastic or whether “plastic little” is enough of a description, stop before you click. Go to the jsp store or whatever supplier you trust, and make the product catalog tell you what you need to choose.

The best order is the one that doesn’t come back. The second-best order comes with a spec sheet you actually read. Once you start verifying materials as a normal part of purchasing, you’ll find that prevention really is cheaper than the cure.