Dow Corning Purchasing FAQ: 5.3oz Vacuum Lubricant, 3145 RTV MIL-A-46146, and E6000 Mix-Ups

I'm the office administrator for a 200-person manufacturing company. I handle all the maintenance and lab supply ordering—roughly $80,000 a year across 8 vendors, and I report to operations and finance. Most of my orders are boring, but the Dow Corning ones get questions.

Here are the actual questions I get from engineers and the maintenance crew, plus a few I think every buyer should ask.

Is Dow Corning vacuum lubricant in the 5.3oz tube the same as regular silicone grease?

No. Dow Corning vacuum lubricant, 5.3oz tube, is a high-vacuum grease made with silicone and designed for vacuum systems, O-rings, and ground-glass joints. Regular silicone grease won't hold up under vacuum and can outgas. The 5.3oz tube is a nice size for bench work, but I still read the technical datasheet before ordering because "vacuum" doesn't mean "all-purpose."

The part number matters more than the color of the tube. If you're not sure, buy the tube that lists the vacuum range and temperature range on the label. If a cheaper tube looks like the same grease, that's a red flag to me. I'd rather pay for documented performance than gamble on a seal failure in the field.

Can Dow Corning 3145 RTV MIL-A-46146 adhesive sealant be used instead of E6000 adhesives?

Not as a drop-in swap. Dow Corning 3145 RTV MIL-A-46146 adhesive sealant is a one-part silicone adhesive sealant with good heat resistance and electrical properties. E6000 adhesives are industrial-strength and flexible, but they're not the same chemistry. Both come in tubes, and both smell super strong, but that's where the similarity ends.

If you need a MIL-A-46146 silicone sealant for electronics or high-temp bonding, 3145 is a solid choice. If you're bonding porous materials or doing craft repair, E6000 might be what you actually need. I once saw a purchase request say "same as 3145" and the buyer ordered E6000 because they were both "adhesive in a tube." Check the datasheet, not the tube shape.

What does MIL-A-46146 mean on the Dow Corning 3145 datasheet?

MIL-A-46146 is a military specification for a one-part RTV silicone adhesive sealant. It covers tensile strength, elongation, and adhesion to common substrates like aluminum and steel. When a contract calls out MIL-A-46146, you need the material to be tested against that spec, not just "similar."

For Dow Corning 3145, that designation is important for aerospace, defense, and some industrial electronics work. If you're buying for a government job, ask the distributor for the certification or the CAGE code before you order. Looking back, I should have asked for certs in the RFP during our 2024 vendor consolidation project. At the time, I assumed the spec on the datasheet meant the vendor would handle the paperwork. It didn't, and we lost a week expediting the right documentation.

Can I use Dow Corning vacuum lubricant on powder-coated parts? (Asking for a powder coating shop in Buffalo)

This one came from a powder coating shop in Buffalo that had sticking spindles on their line. The short answer is no. Powder coating is a surface finish, and a high-vacuum lubricant is not a general-purpose industrial grease. It's not designed for the loads, temperatures, or dust you get on a powder coating line.

For powder coating line maintenance, you want a high-temperature chain or bearing lubricant, not a vacuum grease. And if you need to lubricate a finished powder-coated part, the coating is already cured, so that's a different application entirely. It's tempting to grab the first tube with "silicone" on it, but the application has to drive the product choice.

Are corn starch and baking powder the same?

No, and this is the question I never expected to tie back to Dow Corning. Corn starch is a thickening agent. Baking powder is a leavener, and it often contains corn starch as a carrier. If you swap them, your biscuits will be dense in a way that no amount of butter can fix.

Why am I putting this in a Dow Corning buying FAQ? Because product mix-ups happen exactly this way. Someone remembers "that white powder in a tube" or "that clear adhesive like the other one," and orders from memory instead of from a part number. Maintenance once asked me for "that grease in the grey tube" and meant 3145 RTV. The tube was grey. The product was not grease.

So, no: corn starch and baking powder are not the same. Neither are vacuum lubricant and RTV sealant. Read the label.

Is the Dow Corning 5.3oz tube worth the price versus off-brand silicone?

I can't tell you which brand to buy for your operation, but here's how I decide. For a product like Dow Corning vacuum lubricant in the 5.3oz tube, I look at what's included: documented vapor pressure, temperature range, shelf life, and lot traceability. Off-brand tubes can be fine, but if they don't come with that information, I can't verify performance.

The unit price is way less important than the total landed cost. The conventional wisdom is to compare unit prices. My experience with hundreds of orders says the cheapest quote is rarely the cheapest total cost. Shipping, hazmat fees, and reordering after a failed tube are all part of the real price. I've learned to ask "what's NOT included?" before I ask the price. A vendor who lists all fees upfront, even when the total looks higher, usually costs less in the end. That has been true for me since I took over purchasing in 2020.

What's the best way to order Dow Corning 3145 RTV and vacuum lubricant without making a mistake?

Use the full product name and part number. For 3145, write "Dow Corning 3145 RTV MIL-A-46146 adhesive sealant" on the PO, not just "3145." For the lubricant, specify "Dow Corning high-vacuum lubricant, 5.3oz tube," and include the part number from your distributor. If your ERP system lets you attach a file, include the datasheet link. That has saved me more times than I can count.

Check lead times too. A single 5.3oz tube might be in stock, but a case of 12 might have to come from a regional warehouse. In our 2024 vendor consolidation project, we moved most of our Dow Corning buys to a distributor with a web portal and transparent shipping. It cut our ordering time from about two hours a week to thirty minutes and eliminated surprise freight charges. For that reason alone, an online distributor with clear fees is a no-brainer.

What should I ask before buying Dow Corning products from a new vendor?

Three things: Are you an authorized distributor? Do you provide certifications for military-spec items? What does the total delivered price include? If any answer is fuzzy, treat it as a red flag. I process 60-80 orders a year, and the vendor who couldn't provide proper invoicing cost us $2,400 in rejected expenses. Now I verify documentation before placing any order.

To me, transparency is the deal-breaker. If a salesperson says, "that spec won't be a problem" but won't put it in writing, that's a red flag. Bottom line: Dow Corning materials are reliable when you buy the right product and get the paperwork you need. The extra five minutes it takes to verify costs less than the expedite fee you'll pay later.