Loctite Chart: Which Loctite is Removable? A Procurement Perspective

What Loctite actually does (and doesn't do)

If you've ever ordered Loctite for your team, you know it's not just threadlocker—it's a whole system. But here's the thing: it took me a couple of years and about 40 different orders across 8 vendors to really get the Loctite chart.

When I took over purchasing in 2020, I thought all threadlockers did the same thing. They don't. The strength spectrum—from low-strength (removable) to high-strength (permanent)—matters a lot more than the tube color. Let me break it down.

Bottom line: Loctite threadlockers are anaerobic—they cure in the absence of air and in the presence of metal ions. But their strength varies wildly depending on the formula.

Question 1: Which Loctite is removable?

Probably the most common question I get from our maintenance team. And the answer is:

• Loctite 242 (blue) — Medium strength. Removable with hand tools. This is the most popular for general service, like bolts on machinery covers.
• Loctite 222 (purple) — Low strength. Removable with light hand tools. Great for small fasteners, like set screws on electrical enclosures.
• Loctite 243 (blue, oil-tolerant) — Medium strength. Similar to 242, but works on slightly oily surfaces. Also removable.

Which Loctite is not removable? Anything in the red family—Loctite 271 (high strength) and 272 (high temp, high strength). Those are basically permanent without heat or special tools. If you put 271 on a bolt you'll be taking an angle grinder to it. Trust me on this one.

I want to say 242 covers about 70% of our needs. But don't quote me on that—it depends on your application.

Question 2: How do I read the Loctite chart?

The Loctite chart is actually pretty straightforward once you know what you're looking for. It's color-coded by strength:

• Purple (222) — Low strength, removable
• Blue (242, 243) — Medium strength, removable
• Red (271, 272) — High strength, permanent
• Green (290, 294, 603, 638, etc.) — Wicking grade or retaining compounds. Green can mean wicking (for pre-assembled fasteners) or high-strength retaining (for cylindrical parts like bearings).

But the chart also includes technical specs like torque strength, temperature range, and gap fill. For example, Loctite 272 handles temps up to 450°F, while 271 only goes to 300°F. If you're working on a hot motor, that distinction matters.

It took me 3 years and about 150 orders to understand that the chart is a reference—not a rulebook. The actual performance depends on the base material, cleanliness, and temperature. So use the chart as a starting point, then test.

Question 3: Can you use Loctite on any fastener?

No, and this is a common mistake. Loctite threadlockers are designed for metal fasteners—steel, stainless steel, iron, bronze, and brass. But there are exceptions:

• Stainless steel — Can be slow to cure. A primer (Loctite 7649) helps.
• Plastic fasteners — Don't use anaerobic formulas. They can cause stress cracking. Use cyanoacrylate or epoxy instead.
• Pre-coated fasteners — Some fasteners already have a microencapsulated adhesive. If you use more Loctite, it may not work because the surface is already sealed.

The surprise wasn't the fasteners that worked—it was the ones that didn't. I had a batch of stainless steel bolts that refused to cure properly. At first I thought we ordered the wrong formula. Turns out we just needed a primer. After 5 years of managing procurement, I've come to believe that the 'best' product is context-dependent.

Question 4: How long does Loctite cure?

Functional strength (handling) typically takes 20-30 minutes at room temperature. Full cure takes 24 hours. But temperature matters:

• Cold (below 50°F / 10°C) — Cure time doubles or more. Not recommended.
• Room temp (68-77°F / 20-25°C) — 24-hour cure.
• Hot (above 100°F / 38°C) — Cure time decreases, but performance may degrade if it gets too hot during cure.

The most frustrating part of using Loctite: waiting for full cure when you need the machine back online. You'd think a 24-hour cure in a 400°F environment would be accelerated, but the anaerobic cure reaction stops above 300°F. So if you apply it to a hot surface, it may never cure properly.

What finally helped was building in buffer time and using Loctite 243 (oil-tolerant) for surfaces that are harder to clean thoroughly.

Question 5: Does Loctite work on packaging equipment?

Yes, but you need the right product. For packaging machinery—conveyors, sealing equipment, filling heads—standard threadlockers work fine on bolts and fasteners. But if you're dealing with sealing gaskets on pumps or valves, you want a sealant like Loctite 518 (flange sealant) or 567 (thread sealant), not a threadlocker.

Here's what you need to know: the wrong Loctite can cause gasket failure. Using a threadlocker on a flange joint is like using super glue to patch a tire—it's the wrong tool.

Heads-up: For hot-melt adhesive equipment, you might need Loctite 480 (instant adhesive) for bonding plastic parts, but not threadlockers. They're different families.

Question 6: How do you remove red Loctite?

You don't—unless you have heat. Red Loctite (271, 272) requires 450-500°F (232-260°C) for 5-10 minutes to soften. Then you can disassemble with hand tools. Without heat, you're likely to snap the bolt.

Loctite 262 (also red) is marketed as a 'high strength, don't use unless you mean it' formula. It requires tools to remove but is technically removable—but I've found it just as stubborn as 271 in practice.

Which Loctite is removable? The answer: purple, blue, and green (wicking) grades are removable. Red and green (retaining) grades are not. But the key distinction is intent. You use red when you want a permanent assembly that you expect to replace the fastener rather than reuse it.

Take it from someone who snapped a bolt: use the right strength for the job. A red Loctite on a removable panel is asking for problems later.

Question 7: What if I accidentally use the wrong Loctite?

It happens. Even our senior techs have done it. If you put blue on a high-temp fastener and it fails, you need to clean and reapply the correct grade. If you put red on a removable fastener, you need to heat it or replace the fastener.

But here's a trick: if you accidentally use green wicking (290) when you meant to use threadlocker, it's actually okay. Green wicking is a low-to-medium strength post-assembly threadlocker that seeps into threads. It's removable with hand tools. Not ideal, but not a disaster.

After the third late delivery from the same vendor (not Loctite, but just bad service), I realized that ordering the wrong Loctite is usually fixable—as long as you caught it before full cure. If it's already cured, it's a lesson for next time.

Pro tip: Use Loctite 243 for oily surfaces and Loctite 242 for clean surfaces. If you're unsure, go with 243. It's more tolerant of imperfect prep. An informed customer asks better questions and makes faster decisions.