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A Field Checklist for Loctite 572, Loctite 660 Retaining Compound, and Loctite Marine Epoxy

Who This Checklist Is For

If you buy Loctite products for maintenance and repair, this is for you. I'm a maintenance planner, and I've handled service orders for industrial and packaging equipment for six years. I've personally made and documented 14 significant mistakes, totaling roughly $9,300 in wasted budget. Now I keep this checklist so the next person doesn't have to repeat them.

There are five steps. That's it.

When I first started choosing Loctite products in 2019, I assumed the strongest one was the right one. Red, high strength, done. Three bad repairs later, I learned that the right question is not 'is it strong enough?' It's 'is this the right product category for what I'm doing?'

Step 1: Match the Product to the Actual Task

Loctite 572 is a thread sealant. Loctite 660 retaining compound is a product for cylindrical assemblies. Loctite Marine Epoxy is a two-part epoxy for structural bonding, especially in wet areas. These are not three strengths of the same thing.

According to Henkel's current Loctite product datasheets (henkel-adhesives.com, accessed April 2025), each product has a specific job. I'm not going to recite spec numbers from memory; check the current datasheet before you order.

I put Loctite 572 on a machine screw once because I thought 'thread sealant' was close enough to 'threadlocker.' Actually, let me rephrase that: I used it because I was in a hurry. It didn't hold, and the alignment drifted. Wrong category, every time.

• Sealing a threaded pipe or fitting? Consider Loctite 572.
• Restoring a worn shaft or bearing fit? Consider Loctite 660 retaining compound.
• Bonding a damp surface or doing a wet-area repair? Consider Loctite Marine Epoxy.

Step 2: Check Temperature, Chemical, and Water Exposure

Before you order, write down the operating conditions. That's not busywork. I once chose an epoxy for a sensor bracket that ran at about 65°C, about as warm as a heated coffee cup Ember. The epoxy softened, the bracket shifted, and the sensor read wrong for an entire shift. The redo cost $680 plus a one-day delay.

If the joint will see water or washdown, Loctite Marine Epoxy is a better starting point. If it's a threaded fitting that needs sealing, Loctite 572 is one of the products worth checking. Temperature ratings are not a suggestion.

Step 3: Measure Before You Order Retaining Compound

Loctite 660 retaining compound has saved me when I thought the only fix was a new shaft. But it has a gap limit, and the limit depends on the product and surface preparation.

For bearing fits, I look up the exact dimensions in the Nachi catalog. That catalog tells me the nominal shaft diameter, housing bore, and tolerance. Then I measure the actual worn part. If the clearance is outside the datasheet limit, no retaining compound is going to make it right.

I was told to measure before ordering. I didn't. The shaft had a taper I hadn't seen. The Loctite 660 held the bushing for two hours, then the bushing spun. That replacement cost $2,100 and a piece of my credibility.

Step 4: Plan the Disassembly Before You Cure It

I went back and forth between Loctite 660 and a replacement shaft for two days. The new shaft was about $480; the retaining compound was a fraction of that. On paper, 660 made sense. But I still had to answer: what happens when this assembly gets opened next year?

Loctite 660 is strong. It isn't 'fit it and forget it forever' when removal is part of the maintenance cycle. If your maintenance schedule requires disassembly, read the removal instructions in the datasheet before you commit. Also plan for cure time. I want to say that job took about six hours, but don't quote me on that—we got pulled to another failure in the middle.

Step 5: Document It So the Next Person Doesn't Become Me

A repair isn't finished when the torque wrench clicks. It's finished when the next person can read what you did. Write down the Loctite product number, the surface preparation, the cure time, the application location, and the date.

And if you've been searching 'what is the Chicago Manual of Style,' here's the short answer: it's a style guide for writing and editing, not an engineering standard. I use a simple format in our logs. The important thing is consistency, not whether you cite the Chicago Manual of Style edition perfectly.

An informed person makes better decisions. I'd rather spend five minutes explaining a product than deal with the phone call after a $2,100 mistake.

Notes From the Mistake File

Don't Trust the Color or the Screw Cap

Loctite 242 and 271 look different if you know the code. But if you grab a tube from the drawer and assume it's the same product you used last month, go back to Step 3. Colors are a visual clue, not a spec.

Clean the Surface Like It's the Only Thing That Matters

Many Loctite products need a clean, dry surface. I once thought a shaft was clean because it looked clean. Grease always wins. Use the correct cleaner or solvent, then dry it.

Check the Shelf Life

I found an old bottle of Loctite 660 retaining compound in a bottom drawer. It looked fine. It wasn't. If the package has a use-by date, honor it.

That's the list. It's not glamorous, but it keeps me from ordering the wrong Loctite 572, Loctite 660 retaining compound, or Loctite Marine Epoxy. If it helps you avoid one bad repair, it's paid for itself.