After five years as the person who buys everything for a 400-person manufacturing company, here's the honest conclusion: Dow Corning makes the most reliable silicone sealants and vacuum lubricants I've purchased, but they aren't the answer to every materials question. The 732 sealant has held up on our facility roof for three years where cheaper brands failed in six months. The High Vacuum Grease has outlasted every petroleum alternative we tested. But the best way to thicken soup is still corn starch, and the best answer I can give about removing AR coating from glasses is "talk to an optician." Learning the difference between these situations has saved this company about $2,400 in direct costs—and a lot of embarrassment.
Let me tell you who's writing this, so you know what I can and can't speak to. I'm not a chemist or an engineer. I manage procurement—office supplies, maintenance materials, lab consumables, and the occasional cafeteria request. I've been doing this since 2020, processing 60-80 orders annually across 8 vendor categories. Total annual spend is roughly $1.2 million, and my name goes on the purchase orders. So I've developed strong opinions about what's worth buying.
This isn't a product manual. It's a field report from someone who's made expensive mistakes so you don't have to.
Dow Corning Silicone Sealants: Which One to Buy
If you searched "dow corning silicone sealants" and need a quick answer: Dow Corning 732 for general sealing, 736 for high-temperature work, 795 for structural glazing. If you only stock one, stock 732. That's it.
Here's why. The 732 is a general-purpose silicone sealant rated from -85°F to 350°F continuous. It handles HVAC penetrations, metal framing, weather sealing, and most industrial applications. It cures flexible and stays that way. We've relied on it since 2020.
I learned its value the hard way. In my first year, I found a no-name sealant that was 40% cheaper, ordered 24 cartridges, and saved roughly $180. Six months later, it had cracked across every HVAC penetration on the roof, and the leaks caused $2,400 in rework and downtime. It was a classic rookie mistake, and it taught me a simple rule: don't cut corners on materials that hold your building together.
A few caveats. If the application is near ovens, exhaust stacks, or other high-heat sources, get the 736 heat-resistant version—it handles continuous exposure up to 500°F. If you're sealing structural glass (curtain walls, glass railings), get the 795. It's specifically rated for structural glazing, and no, you shouldn't substitute 732. It doesn't have the specifications for load-bearing glass.
Also: check what you're sealing onto. In 2023, we ordered 732 for a polycarbonate panel job and it peeled right off. Silicone sealant doesn't stick to certain plastics and coated surfaces. Dow Corning's technical data sheets (available on the DOWSIL website) list compatibility—read them before you order, not after.
Silicone sealant also isn't paintable. Paint won't adhere to cured silicone. If your contractor plans to paint over it, use a paintable caulk instead.
Dow Corning Vacuum Lubricant: Is It Worth It?
Yes. Dow Corning High Vacuum Grease is the most reliable product I've ever reordered. The 5.3 oz tube costs around $25-35 based on online supplier listings as of January 2025 (verify current pricing). A single tube lasts us 6-8 months, so it's not a significant line item.
The reason it's worth it comes down to chemistry—and trust me, I'm not a chemist, I just read the spec sheets. Silicone-based grease has low vapor pressure, which means it doesn't outgas inside vacuum systems. It doesn't harden over time the way petroleum grease does. It stays where you put it, keeps O-rings flexible, and doesn't contaminate the equipment. When you're dealing with vacuum pumps and fittings, that matters.
In 2022, our maintenance team decided to save about $10 per tube by switching to a generic petroleum vacuum grease. A few months later, a valve seized because the grease hardened. The repair cost $600. Cheaper, in that case, was dramatically more expensive. (Note to self: don't let people "optimize" things you've already standardized.)
Here's the boundary condition: do not use High Vacuum Grease near food. It's not food grade. For food processing equipment, you need a specifically rated food-grade lubricant from the DOWSIL line, with NSF or FDA certification visible on the label.
Silicone Filament for 3D Printing: Overrated for Most
People searching "silicone filament" usually want to know if it's worth trying. My honest take: unless you need parts that handle heat or chemicals beyond what TPU can manage, silicone filament is not worth the trouble.
We tested it in 2024. Our engineering team wanted flexible, heat-resistant gaskets for a prototype. We bought a $90 spool (prices range from $60-100 depending on brand and quality, as of January 2025). Then we discovered the printer needed a modified extruder because silicone's viscosity behaves nothing like PLA or TPU. We spent three weeks calibrating, produced one usable part, and went back to TPU. The whole experiment cost us time and money without delivering a practical result.
When would silicone filament make sense? If you need a prototype that must withstand constant temperatures above what TPU handles, or resist certain solvents. For those cases, silicone filament is one of the few options. But those are engineering decisions, not procurement decisions.
The Odd Ball: Corn Starch to Thicken Soup
Here's the keyword that made me smile: "corn starch to thicken soup." Why is it in an article about Dow Corning? Because our cafeteria manager asked me the exact same question last year.
The answer: yes, corn starch thickens soup reliably, and it's a naturally gluten-free option. Mix one tablespoon of corn starch with two tablespoons of cold water to create a slurry, then whisk it into hot soup. It thickens in about a minute once the starch activates. One tablespoon will thicken roughly one cup of liquid.
Don't dump dry corn starch directly into hot liquid. You'll get lumps. I've seen it happen in our cafeteria—and once in my own kitchen. The slurry method works because the cold water separates the starch granules before heat activates them.
What does this have to do with materials? The same principle that applies to silicone sealants applies to food thickeners: use the right material for the job. Corn starch is the right material for soup because it's effective, food-safe, and cheap. Dow Corning is the right material for vacuum seals because it's reliable, consistent, and tested. Different jobs, different materials, same principle.
The Eyewear Question: How Do You Remove AR Coating from Glasses?
Here's a question I see a lot in search data. You can remove AR coating from glasses with baking soda paste or commercial coating-removal products, but attempting it at home is risky. You can easily damage the lens, scratch the anti-scratch layer, or create hazy spots that can't be fixed.
I'm not an optician, so this is where my expertise ends. What I can tell you from a purchasing perspective: replacing lenses with a fresh AR coating typically costs $50-150 depending on prescription and provider (pricing varies by location—verify with local optical shops). Some providers will remove a defective AR coating for free if it's under warranty. In 2024, one of our employees had her lenses replaced at no cost because the coating peeled within the first year.
The DIY route with baking soda paste can work on some lenses, but the risk of scratching is high. I've seen two employees ruin perfectly good glasses trying this after watching tutorials online. (Surprise, surprise.) If the coating is peeling or scratched, the practical solution is professional: recoat, replace, or wait for the next prescription. Don't let ten minutes of YouTube convince you to experiment with your vision.
Where My Expertise Ends
I promised you a conclusion at the start, so here are the caveats instead of a summary.
First, prices move. The figures I mentioned were accurate as of January 2025 based on major online supplier listings. Verify current rates before budgeting.
Second, the brand has quietly evolved. Dow Corning is now DOWSIL in many markets after the 2016 ownership transition. Product numbers like 732 and 736 didn't change, but labels and certifications did. Read the current technical data sheets.
Third, my knowledge has a ceiling. I know what works in a real manufacturing facility from five years of buying and watching. I don't know how these products behave in medical, aerospace, or pharmaceutical environments. If you're working in those industries, get an engineer involved.
The honest principle: the premium brand isn't always necessary, and the cheap option isn't always wrong. The right product fits your actual conditions. For us, Dow Corning has consistently fit. Corn starch has also fit. The skill is knowing which one you need.