In my role coordinating emergency repairs for packaging and printing plants, I get the same questions on repeat. Last quarter alone, my team worked 47 rush jobs with a 95% on-time rate — and a solid third of those were adhesive-related. The product on the line changes every week: a capping station that fills 50ml spray bottles, a conveyor unit for a single coffee cup maker, a wrapper with a heat-seal bar running hot. The underlying problem is usually the same. A fastener backed out. A bearing walked. A thread leaked. And somebody's asking me: "Which LOCTITE do we need, and can we have it today?"
This is the comparison I wish someone handed me when I started doing this six years ago. LOCTITE 272 vs. 271. 609 vs. 680. The "is LOCTITE super glue waterproof" question. And the Teflon tape on gas fittings issue that shows up more than it should. I'll put a verdict at the end of each section, because you're probably reading this with one eye on a downed line.
LOCTITE 272 vs. 271: Same strength, different temperature ceiling
Both are high-strength threadlockers — red, anaerobic, and a pain to remove if you pick wrong. They are not interchangeable, though. I've seen the consequences of treating them like they are.
The headline difference comes straight from the LOCTITE technical data sheets: 271 is rated for continuous service up to 150°C (about 300°F). 272 is rated up to 230°C (about 450°F). These are current specs as of early 2025 — always check the latest TDS revision at Henkel's site before you spec anything, because formulations do get updated.
Here's a concrete example. In March 2024, 36 hours before a client's seasonal restart, I got called to a packaging plant where the heat-seal bar's mounting bolts had worked loose — for the third time. The maintenance log showed two previous fixes with 271. Each held about six weeks, then gave up. I checked the seal bar surface temp: 185°C. The 271 was hitting its ceiling and releasing. Swapped to 272, torqued to spec, done. It's still running as of this writing.
That said, 272 has a reputation as "the strong one," so people order it for everything. That's overkill. At normal room-temperature assemblies — conveyors, guards, general machinery — 271 cures faster and does the same job for less money. 272 only earns its keep in hot zones.
Verdict: Under 150°C service, pick 271. Above that, or with serious heat cycling, pick 272. Don't buy 272 "just in case" — you're paying for a temperature rating you don't need.
LOCTITE 609 vs. 680: The clearance is the answer
Retaining compounds solve a different problem. When a bearing spins in its housing or a shaft wears in a bore, you're not locking threads — you're filling a cylindrical gap between two metal parts. 609 and 680 both do this. The difference is how much gap they handle, and I think people grab the wrong one more often than any other mistake I see.
609 is rated for gaps up to about 0.005" (0.13 mm). It's low-viscosity, wicks into close-fit assemblies, and cures fast. If a bearing is a couple thousandths loose in the bore — the classic slip-fit repair — this is your product.
680 handles gaps up to about 0.015" (0.38 mm). It's thicker and bridges real wear. But here's the counterintuitive bit: a thick bond line is a weak point, not a strength. If your clearance is 0.003", a thin 609 film will hold better than a thick 680 layer would. Choosing 680 "to be safe" for a tight fit is backwards.
Real case from last year: a client's capping turret on their 50ml spray bottle filling line had walked its housing down to about 0.010" clearance. That's what 680 is for. It saved a turret replacement that would have cost thousands and weeks of lead time. The repair took one afternoon. The same machine had a secondary shaft boss at 0.003" — 609, and done.
One more thing about sourcing. When a maintenance manager Googles "loctite 609 near me" at 7am, the hardware store usually doesn't have it. That's not a knock on them — it's a stocking reality. Industrial bearing suppliers and adhesive distributors carry it. I keep a 50ml bottle in my service case, which covers fifteen to twenty bearing repairs. Call a supply house, not a retail store.
Verdict: Measure the clearance. Under 0.005", use 609. Between 0.005" and 0.015", use 680. I know you're gonna eyeball it — at least use a feeler gauge. Guessing is how you get repeat failures.
Is LOCTITE super glue waterproof?
The short answer? No. Not really.
Standard cyanoacrylate — LOCTITE 401, 404, that family — is water-resistant. It'll handle a splash, some humidity, an occasional rinse. But constant immersion or regular washdown with pressurized water and cleaning chemicals will break it down. That's not a defect; it's chemistry.
I learned that the expensive way. Bonded a sensor bracket in a washdown enclosure on a packaging line with standard CA. It lasted three weeks before letting go during a 2am sanitation cycle. (Which, honestly, was three weeks longer than I should have trusted it.) Looking back, I should have gone straight to epoxy. At the time, slapping a temporary bracket with CA seemed reasonable — not worth a full downtime. But three weeks later, I was back, and the line was down anyway. The permanent fix was a two-part LOCTITE epoxy, which is rated for water exposure. Still holding.
Wait, let me be precise. When I say "waterproof," I mean continuous immersion or repeated wet conditions. Not "it got rained on once." For the occasional splash, CA is fine.
I'm not a chemist, so I can't walk you through the polymer science. What I can tell you from a maintenance perspective: if the joint will see regular water, use an epoxy rated for water exposure. The cure time is longer and you lose a little convenience, but you won't be redoing the job a month later.
Verdict: LOCTITE super glue handles occasional moisture, not continuous water. For ongoing wet service, choose a LOCTITE epoxy.
Should you use Teflon tape on gas fittings?
This one deserves a careful answer because it's a safety question.
Yes, you can use PTFE tape on natural gas and propane fittings — but only the yellow tape that's gas-rated, applied properly. White plumbing tape is not certified for gas. Wrap clockwise, two to three layers, and leave the first couple of threads bare. Those threads do the actual metal-to-metal seating; tape wrapped into that zone can shred and travel downstream.
That said, I admit I have mixed feelings about tape as a solution. On one hand, a good yellow tape job is code-accepted in many jurisdictions, and it works. On the other, the failure mode — shredded PTFE blocking tiny orifices — is nasty enough that I prefer paste sealant. LOCTITE 567 is rated for gas service, easier to apply consistently, and it doesn't shred.
Also, and I can't say this strongly enough: do not use a threadlocker on a gas fitting. Threadlocker and thread sealant are different products. Putting 272 or 242 on a gas thread won't create a pressure-tight seal, and most threadlockers aren't gas-rated. Read the label. Use the right thing.
The most frustrating part of this whole topic: the right answer is printed on both products. But nobody's reading the label at 10pm with a leaking fitting in their hand.
Verdict: For lasting gas service, use a gas-rated paste sealant like LOCTITE 567. Yellow gas-rated tape is an acceptable stopgap if applied perfectly. White tape is never acceptable.
What goes in your maintenance kit
If I'm building a kit for a packaging or printing plant, it's roughly this:
- LOCTITE 242 — medium-strength threadlocker for things you'll take apart again
- LOCTITE 271 — high-strength threadlocker for standard temps
- LOCTITE 272 — high-strength threadlocker for hot zones
- LOCTITE 609 — retaining compound for close-fit bearings and shafts
- LOCTITE 680 — retaining compound for worn parts with visible clearance
- LOCTITE 567 — thread sealant for gas and liquid thread joints
- LOCTITE two-part epoxy — waterproof structural bonds
Not in the kit: white Teflon tape, and threadlocker used as a sealant. Those are the two mistakes I've been called in to undo more times than I can count.
I'll close with the boundary that matters: I'm an emergency repair coordinator, not a design engineer. If you're putting this into a product that ships, or into a safety-critical fuel line, bring in the engineers and check the codes. But if a line is down and you need the right call under pressure, the comparisons above have carried me through 200+ jobs.
Now go check those fittings. Seriously.
