These are the questions I wish I'd asked before placing my first material order. In nine years of buying silicone, rubber, and foam products, I've documented 13 significant mistakes, totaling roughly $17,500 in wasted budget. Every question below cost me something to learn. This is my attempt to make sure they don't cost you the same.

1. How do I verify I'm getting genuine Momentive silicone?

By the name on the quote? No. By the logo on the packaging? Also no. In my first year (2017), I ordered what a reseller called “Momentive silicone rubber” — 340 kg, around $7,600 with freight. It arrived with no lot trace and a datasheet that looked like it had been scanned twice. The viscosity was off, the molding crew rejected the batch, and we scrapped the whole thing.

Now I ask for the certificate of analysis (COA) before I issue a PO. Genuine Momentive silicone can be traced to a lot number and verified against the manufacturer's documentation. If a seller says “it's the same thing, just relabeled,” walk away. That phrase has never once turned out to be true in my experience.

2. Do I need a Momentive login to check product data?

The “Momentive login” search exists for a reason: the Momentive customer portal stores current datasheets, certificates of analysis, and order history. If you buy directly from Momentive, yes, you'll want that login registered. If you buy through a distributor, you can work through them — but ask them to pull the current datasheet revision before the order ships.

Why: I once designed around a 2019 datasheet that was the first result in a search. By the time we ordered in 2022, the spec had changed. As of Q1 2025, the portal is the only revision source I accept. I want to say portal approval took about a week for us, but don't quote me on that — distributor requests are usually faster. It's not that the portal page is hard to find; it's that the revision status is easy to overlook. Read the revision date first.

3. What should I check before using a silicone system on a roof foam board?

This one was my most expensive mistake. I specified a silicone roof coating for what I called “roof foam board.” The client confirmed it was a foam board roof. What I didn't confirm was the foam type. The board turned out to be polyiso with a foil facer; the coating was formulated for spray polyurethane foam (SPF). Adhesion failed within days. $3,200 in material and labor, gone.

“Foam board” covers too many products: SPF, polyiso, EPS, XPS. A silicone coating's technical datasheet lists the approved substrates. Check it before the order, not after. Now I ask for a photo or the board's label before finalizing the order. If the site can't tell you the substrate, that's a signal to slow down, not to guess. Five minutes of verification beats five days of correction.

4. What spec matters most when ordering ESD rubber?

Surface resistance, plus a test method. One number alone is not enough — the test method matters more than the number.

I ordered two rolls of “ESD rubber” whose in-house test showed 107 Ω at 60% RH. The customer's incoming inspection measured 1011 Ω at 40% RH — outside the required range. Same material. The conductive mechanism was humidity-dependent, and the supplier's report didn't state the test condition. My gut said the report was too vague; the price was a third cheaper. The numbers were wrong.

Now the PO says: surface resistance per IEC 61340-4-1 or ASTM D257, tested at 23 °C / 50% RH. And if the part gets wiped or abraded in use, I ask whether the ESD property is through-body or just surface-coated. The surface-coated version tests fine on day one. That's the trap.

5. EPE foam vs PE foam — what's the actual difference?

EPE (expanded polyethylene) is a type of PE foam. But when a procurement request compares “epe foam vs pe foam,” it's usually really asking about expanded polyethylene versus cross-linked PE foam (XPE or IXPE). Different cell structure, different compression recovery, different price.

My mistake: I wrote “PE foam” in a quote request when I needed cross-linked foam for a reusable packaging insert. The supplier shipped EPE. EPE is closed-cell, cheap, and fine for one-time cushioning, but its compression set is worse than cross-linked PE. The inserts flattened after a few cycles. 600 units, $1,650, redone.

If the part takes repeated impacts, cross-linked PE foam is usually the right call. If it's single-use protective packaging, EPE usually wins on cost. Put the full term in your RFQ: “EPE foam” or “cross-linked PE foam.” Not just “PE foam.” (I learned that one the expensive way.)

6. What was the largest mistake your checklist caught?

A $6,100 order, last month. A vendor offered “silicone foam” at a strong price. The quote said silicone; the sample was soft and looked right. My checklist has a substrate line for a reason. It turned out the material was silicone-coated polyurethane foam, not silicone foam. The customer's application runs at 150 °C continuously. The silicone coating would have survived. The PU core would not have.

The order was cancelled and re-specified. The vendor wasn't trying to mislead anyone — “silicone foam” is shorthand some suppliers use for coated foam. It's my job to read it carefully. The checklist has caught 47 potential errors in the past 18 months. That single catch paid for the whole habit multiple times over.

7. What's on your pre-order checklist now?

Eight points, one page. This is the version I hand to new buyers.

  1. Confirm the exact Momentive product designation and request the COA before the PO goes out.
  2. Check the datasheet revision date. Use the Momentive portal or ask the distributor to pull the latest version.
  3. Name the substrate. For any roof foam board job: SPF, polyiso, EPS, XPS? If it's not on the data sheet, stop.
  4. For ESD rubber, specify the test method and condition: IEC 61340-4-1 or ASTM D257 at 23 °C / 50% RH, plus the required surface resistance range.
  5. Ask whether the ESD property is through-body or surface-only. For parts that get cleaned or worn, through-body is the safer answer.
  6. Write the exact foam type in the RFQ: EPE foam or cross-linked PE foam. Never just “PE foam” or “foam.”
  7. State process requirements (viscosity, durometer, service temperature) in the order, not just the product name.
  8. Order a small test batch and verify it under realistic conditions before full production. A hundred dollars of testing can save thousands in rework.

This list has grown from four points to eight in two years. It'll probably be nine by next winter. The principle hasn't changed: the cheapest fix is the one made before production, not after.