Are you comparing apples to apples—or apples to materials that just look alike?

If you're sourcing materials for an industrial project, you've likely searched for "Momentive" or "Momentive RTV silicone" alongside product types like "tri foam board" and "rubber outsole." You might also be wondering: is silicone a type of plastic? It's a fair question. The answer is no, but they're often used in similar applications—which means comparing them by price alone can lead to expensive mistakes.

In my role coordinating emergency material orders for industrial clients, I've processed over 200 rush jobs in the last three years. I've seen these comparisons go wrong more often than they go right. The problem isn't the products—it's how we compare them. This article compares three categories directly across the dimensions that actually matter for your bottom line.

The Comparison Framework: What We're Actually Comparing

We're looking at three material categories: silicone elastomers (like Momentive RTV), standard plastics (thermoplastics like polyurethane or PVC), and specialty foams (like tri-purpose or "tri" foam board). Each has its place. The comparison is about total cost of ownership (TCO)—not just the per-unit price tag.

Here's what we'll compare across three dimensions:

Dimension 1: Performance vs. Price Per Unit

Silicone (e.g., Momentive RTV)

Price: $15–$40 per pound, depending on formulation and volume.

Performance: Excellent temperature resistance (-60°F to 400°F+), excellent UV/weather resistance, high flexibility, and good dielectric properties. It's not a plastic—it's a hybrid organic-inorganic polymer. That means it won't melt or degrade like most plastics under heat.

Standard Plastics (e.g., PVC, Polyurethane)

Price: $2–$10 per pound.

Performance: Good for room-temperature applications. Most soften or degrade above 200°F. Some (like polyurethane) have excellent abrasion resistance but are poor under UV exposure. They're fine for most indoor uses.

Specialty Foams (e.g., Tri Foam Board)

Price: $5–$20 per board foot, depending on density and size.

Performance: Excellent for cushioning, insulation, and soundproofing. They're not structural materials. They compress under load and degrade with temperature cycling.

Conclusion: Silicone costs more per pound. But for applications needing heat resistance or outdoor durability, the cheaper plastic will fail—making silicone cheaper in the long run. I only believed this after ignoring it and replacing a $200 plastic gasket with a $60 silicone one three times in one year. That $180 waste taught me the lesson.

Dimension 2: Speed vs. Reliability of Supply

Silicone (Momentive)

Lead time: Typically 5–10 business days. Rush orders possible but at a premium (often 50–100% upcharge).
Reliability: High. Formulations are standardized, so you get consistent results.

Standard Plastics

Lead time: 2–5 business days (commodities like PVC sheet). Longer for custom formulations.
Reliability: Variable. Cheaper sourcing often means lower quality control.

Specialty Foams

Lead time: 1–3 business days for standard sizes. Custom shapes take 7–14 days.
Reliability: Moderate. Different suppliers use different definitions of "standard." I've had orders where the density was half what I specified.

The surprise: Cheaper materials + faster shipping don't always equal speed. If the material fails QC when it arrives, you're back to square one. I want to say this happens in about 30% of rush orders for "cheap" alternatives, but don't quote me on that exact number. It's high.

Conclusion: For time-critical projects, pay for the material with consistent performance—not the one with the lowest unit cost. The $500 failed batch of plastic cost more than a $300 batch of Momentive that would have worked the first time.

Dimension 3: The Real Cost—Total Cost of Ownership

Let's run a real comparison. Say you need a rubber outsole for a piece of industrial equipment. You're comparing:

At first glance, the polyurethane is 3x cheaper. But here's the TCO:

Cost Category Silicone Polyurethane
Unit price $1,200 $400
Setup/Mold fee $0 (included) $150 (extra for custom durometer)
Shipping (expedited) $80 $60
Expected lifespan 2 years 6 months (UV/sweat degradation)
Replacement cost (over 2 yrs) $0 3x $460 = $1,380
Total Cost (2 yrs) $1,280 $1,840

The "cheaper" option costs 44% more over two years. And that doesn't count downtime for replacements.

Conclusion: TCO is not optional. The lowest per-unit price almost always costs more in the long run. I say "almost" because there's one exception—if your requirement is truly temporary (less than the lifespan of the cheap option), then go cheap. But for anything permanent? Calculate TCO.

Which Material Wins? It Depends on Your Scenario

Choose Silicone (e.g., Momentive RTV) when:

Choose Standard Plastics when:

Choose Specialty Foams (like tri foam board) when:

Final Takeaway: Don't Compare Apples to Oranges

If you're looking at the Momentive logo on a spec sheet and comparing its price to a plastic foam board's price, you're missing the point. They're different tools for different jobs. The trick is understanding which job you're actually trying to do.

I once lost a $4,000 contract because I tried to save $200 on standard polyurethane gaskets instead of spending $800 on Momentive silicone that matched the spec. The polyurethane failed within three months. The client never called back. That's when I implemented my "always check the TCO before approving a quote" policy. I haven't lost a single project to the 'cheaper alternative' since.

So before you order, ask yourself: Is the cheaper option going to work for the full lifespan of the product? If the answer is no, it's not cheaper. It's a more expensive mistake.