Is Silicone Recyclable? A Dow Corning Silicone Oil, 732, O-Ring Cord Checklist

I work on the quality side of a Dow silicone materials operation. I review outgoing batches before they ship—roughly 200 items a year, maybe 180 if you don't count re-runs. In 2024, I rejected about 9% of first deliveries for spec mismatches. Most weren't catastrophic. They were wrong durometer, wrong viscosity, or a missing lot certificate.

I'm not a chemist, so I can't teach you polymerization. What I can tell you from a QC perspective is how to avoid ordering the wrong Dow Corning silicone and how to answer the question I hear almost weekly: 'Is silicone recyclable?'

Who this checklist is for

Use this if you are buying any of these:

• Dow Corning silicone oil for lubrication, damping, or release
• Dow Corning silicone Dow 732 99179 or another RTV sealant
• o-ring cord for custom gaskets
• silicone cookie molds or other food-contact parts

It also helps if a customer or colleague asks 'is silicone recyclable?' and you don't want to guess.

The 7-step checklist I use

1. Write down the application before you write the part number

Silicone is not one material. Dow Corning silicone oil is a liquid. Dow Corning 732 is a cured sealant. o-ring cord is a rubber profile. A silicone cookie mold is a molded elastomer. They all start with silicones, but the specifications are completely different.

Take one minute to write down: what does it touch? what temperature? any food contact? any chemicals? That sentence filters out more wrong orders than anything else.

2. Pull the current datasheet

For any of these products, the current technical datasheet is the baseline. Ask for the datasheet version and effective date. If someone sends a PDF from 2018, ignore it.

For Dow Corning silicone oil, I look at viscosity and flash point. For Dow Corning silicone Dow 732 99179, I look at cure time, service temperature, and tensile strength. The 99179 code is a specific package code within the 732 family; it tells the distributor exactly which product and size you mean.

For o-ring cord, I ask for a durometer value in Shore A and, if the application is sealing, a compression set value. If you buy to ASTM D2000, the line callout specifies those properties. For silicone cookie molds, I look for food-contact compliance and temperature limits.

Then ask for a lot certificate for the batch. I've rejected batches where the color was right but the viscosity was 12% off spec. The vendor said it was within 'normal production variation.' It wasn't within our agreed tolerance. Now our contract states the test method and tolerance.

Checklist point: no lot certificate, no release. This applies to sample orders too.

3. Confirm the cure system for cured silicone

This step gets skipped more often than it should. There are different ways to cure silicone rubber, and the chemistry affects food safety and long-term sealing.

For silicone cookie molds, I ask for food-grade platinum-cured silicone with a compliance declaration to FDA 21 CFR 177.2600. For o-ring cord, the cure system affects compression set—if a gasket has to seal under constant pressure, that matters. For Dow Corning 732, it's a one-part moisture-cure RTV, so it needs air and humidity; thick blobs may not cure in the middle.

From the outside, all cured silicone looks similar. The reality is that cure chemistry determines whether the part is safe for food contact and how long it seals.

4. Order a sample before you order a production quantity

Small sample orders are not a nuisance. I've been the person with a $200 order and a tight deadline. One sales rep tried to move me to a 'small order' line that didn't answer. I won't name the supplier, but I didn't forget it. The vendors who treated small orders seriously are the ones I later called for $20,000 production runs. Small doesn't mean unimportant; it means potential.

If you're switching silicone cookie mold suppliers, order two molds first. If you need o-ring cord, buy a short length and test it in the actual groove. If you need Dow Corning silicone oil, order a small bottle and check compatibility with the seals, paints, or plastics it will touch.

5. Do a 10-minute incoming inspection

When the order arrives, don't just check the shipping label. Measure what matters.

• For o-ring cord: measure the diameter with calipers in at least three places.
• For silicone oil: check the lot number, color, and viscosity at the specified temperature if you have a viscometer.
• For silicone cookie molds: look for flash, tears, and surface contamination.
• For Dow Corning 732 sealant: confirm the SKU and the manufacture date.

One time I had 20 minutes to approve a small sample before a courier deadline. Normally I'd run a full viscosity test. With a $300 order, I checked the lot number, flash point, and package integrity, then approved it with conditions. The upside was meeting the deadline; the risk was shipping something unverified. I kept asking myself: is one sample order worth a potential field failure? It worked out, but I wish I had kept a physical sample. Now I cut and keep a test piece from every lot.

6. Find out what 'recyclable' means for the specific product

So, is silicone recyclable?

Here is the honest answer: sometimes, but not through a curbside bin.

Cured silicone is a thermoset, so it can't be melted and remolded like a thermoplastic. It can be recycled in industrial loops—for example, clean production scrap can be ground into powder and reused as filler, or depolymerized back into silicone oil. That requires a collection system and a processor. It is not something a typical recycler handles.

Silicone cookie molds, used o-ring cord, and leftover sealant tubes should not go into household recycling. If a supplier says '100% recyclable,' ask them to show you the take-back program in writing.

I don't have hard data on industry-wide recycling rates. Based on our plant's waste records, less than a third of our clean silicone scrap goes into reclamation. The rest is used for energy recovery or landfilled. That's not a great answer, but it's a realistic one.

The 'all silicone is recyclable' idea comes from an era when manufacturers mainly recycled their own in-house scrap. Today, the constraint is collection, not chemistry. At least, that's been my experience with industrial and food-contact grades.

7. Keep a file with the spec and the sample

This is the step that saves you later. Save the datasheet version, the lot certificate, a photo of the sample, and any email about recycling or compliance. If you reorder the same Dow Corning silicone Dow 732 99179 in six months, you'll have a baseline. If a cookie mold fails in a customer's oven, you can trace exactly what you supplied.

Common mistakes I review every year

• Ordering silicone oil by name without a viscosity grade. Viscosity matters more than brand.
• Using the first o-ring cord sample that fits, without checking durometer. A soft cord can extrude under pressure.
• Assuming every silicone cookie mold is food safe just because it is silicone. Additives and cure chemistry matter.
• Ignoring cure time for Dow Corning 732. It is 100% silicone, but it is not instant.
• Believing 'recyclable' means 'put it in the green bin.' It doesn't.

What I'd skip

I would skip the cheapest supplier if they won't share test data. Price is meaningless if the batch is out of spec.

I would also skip a supplier that treats a sample order like a nuisance. If they can't answer questions on a small order, they won't answer them when your line is down. Period.

Bottom line

Is silicone recyclable? Some of it, through the right channel. Is Dow Corning silicone worth buying in the correct grade and checking before use? Yes. Use this checklist, ask for the certificate, and keep a sample. That's it. Done.