Two years ago, I sat at my desk with two rubber samples, a stack of invoices, and a serious case of tunnel vision. The supplier on the phone kept saying “silicone is premium.” The other said “buna is cheaper.” Neither told me what the material would actually cost us over 18 months of maintenance. That framing mistake is why I’m writing this.

I manage procurement for a mid-sized industrial maintenance company. We spend roughly $180,000 a year on sealing materials, rubber sheet, gaskets, and related consumables. I’ve been tracking every purchase order for six years. It took me about 200 purchase orders and one emergency shutdown to realize that the sticker price was the least interesting number on the invoice. So when I compare Momentive silicone rubber and buna rubber sheet, I’m comparing total cost of ownership, not unit price.

Why These Two Materials End Up in the Same Conversation

In the sealing world, Momentive silicone rubber and buna rubber sheet are both “rubber sheets” to the untrained eye. But they solve different problems. Momentive’s silicone materials carry a long history—some of the current product lines trace back to GE Silicones, and engineers still ask for GE Momentive silicone by habit. Buna-N, on the other hand, is the workhorse of oil-resistance applications.

So the comparison is not “which is better.” It’s: for this specific service, which one costs less over its useful life? That’s the only comparison worth making.

The TCO Framework I Use

If you’re only comparing price per square foot, stop. I did that for my first two years, and our “budget-friendly” material choices came back to bite us. Here’s what I calculate now:

That last one is the hidden killer. A sheet that seems cheaper on the supplier’s quote can triple in real cost when it fails at 11 p.m. on a Saturday.

Dimension 1: Temperature Resistance

This is where Momentive silicone rubber pulls ahead. General-purpose silicone can handle continuous heat that destroys buna-N. I’ve seen Momentive silicone gaskets hold up in steam traces and compressor discharge lines where buna hardens in weeks.

Buna rubber sheet is rated for moderate temperatures, but “moderate” depends on your process. Once you cross about 250°F, the math changes. In our 2023 summer outage, we used buna on a hot oil pump because it was in stock. The gaskets lasted six days. We replaced eight of them before the vendor even invoiced us. Looking back, I should have ordered silicone immediately. At the time, the lead time scared me off.

Conclusion on temperature: If your sealed surface regularly runs above 250°F, choose Momentive silicone. The buna sheet is not a substitute.

Dimension 2: Oil and Chemical Resistance

Here’s the twist: buna rubber sheet often beats silicone in direct oil contact. Nitrile rubber is literally designed for petroleum-based fluids. Industrial hydraulic oil, diesel, lubricating grease—buna-N is the conventional choice. Silicone can swell or soften in some oils, especially if you’re dealing with certain additives.

To be fair, Momentive’s specialty silicone grades can resist some fluids well. But for a standard maintenance room stocking sheet material, I wouldn’t pay silicone prices for a gasket sitting in hydraulic oil all day at 180°F. Buna does that job without complaining.

Conclusion on oil resistance: For petroleum fluid service at moderate temps, buna is the lower-TCO pick. Silicone’s “premium” label doesn’t help if the chemistry is wrong.

Dimension 3: Compression Set and Long-Term Sealing

Compression set is the nerdy spec that determines whether a gasket keeps sealing after it’s been squeezed. Silicone typically recovers better than buna after compression, which matters in flanged joints and bolted covers that see thermal cycling.

We had a steam-jacketed filter housing where buna gaskets leaked every month. Not catastrophically, but enough that the operators knew the drill: torque the bolts, wait a week, re-torque. Switching to a Momentive silicone rubber sheet gasket cut the change frequency by maybe 75%. That’s not a guess—it’s in our CMMS work order history.

Conclusion on compression set: If you need a seal that relaxes less over time, silicone wins. This is where the “cheap” buna sheet becomes expensive.

Dimension 4: Cutting, Handling, and Waste

Shop labor is a cost too. Buna rubber sheet is denser and heavier; it cuts cleanly but requires sharper blades and more effort. Momentive silicone rubber is generally easier to cut, though it can be tacky or soft depending on durometer. Both generate waste if your team freehands the shapes.

For gasket fabrication, I recommend a water jet or die cutter if you’re doing more than a few parts. The cost per blank drops fast once you stop cutting circles with a utility knife. If you’re small-volume, at least use a template and a brand-new blade.

This is also a good place for a tangent on Styrofoam foam board, because we often order it on the same maintenance requisition. How to cut insulation foam board properly: use a sharp utility knife with long single passes, or a hot wire cutter for thicker panels. Do not push hard—let the blade do the work. I’ve watched crews crush foam edges by forcing a dull knife and then wonder why their insulation board has gaps. Those gaps are an energy cost, not just an aesthetic problem. Cutting clean is a free efficiency gain.

Conclusion on handling: The best material on paper is useless if your shop can’t cut it accurately. Factor fabrication time into the cost comparison.

What About “GE Momentive Silicone” vs. Generic Silicone?

I get asked this a lot. Some buyers see the GE Momentive silicone naming and assume they’re paying for history. My view: the legacy data and process consistency are worth something. When I order a Momentive silicone rubber sheet, I know the durometer and elongation spec are not going to drift between lots. That consistency has a dollar value, even if I can’t easily calculate it.

Would I pay a premium for the name alone? No. Would I pay a premium for lot-to-lot consistency and a traceable product line? Yes. That’s a TCO decision, not a branding decision.

So Which Should You Buy?

Here’s my honest shortcut after six years of procurement data:

I want to say we’ve standardized on one material, but that would be a lie. We now stock both. Before I would have tried to standardize on the cheap one. If I could redo those early decisions, I’d spend more time on the comparison and less time defending the unit price. Given what I knew then, Buna seemed logical. But I didn’t know what I didn’t know about TCO.

If you’re building a quote for your own plant, run every line item through the TCO lens. The best sheet material isn’t the one with the lowest price—it’s the one that fails the least, cuts the easiest, and keeps your process running.