Loctite 638 & Go2 Gel: An Admin's Guide to Buying the Right Industrial Adhesive

Loctite 638 & Go2 Gel: An Admin's Guide to Buying the Right Industrial Adhesive

Office administrator here. I manage all our facility and maintenance supply ordering for a 150-person manufacturing company. When a maintenance tech or engineer asks me to order "some Loctite," I've learned that's not a simple request. It usually means they need something specific for a critical job, and getting the wrong thing can mean downtime or a safety issue.

After five years and managing relationships with about eight different industrial suppliers, I've put together the questions I always ask myself before placing an order. This isn't a technical deep dive—I'm not an engineer. But from a procurement perspective, here's what you actually need to know.

1. "They asked for Loctite 638. What is it, and why is it so expensive compared to regular threadlocker?"

Loctite 638 is a retaining compound, not a threadlocker. Everything I'd read said threadlockers were for screws, so this was my first learning curve. In practice, I found retaining compounds are for press-fit parts—think gears, bearings, or shafts that are pressed into a housing and shouldn't ever slip.

It's pricier because it's designed for a different, often more critical job. If a threaded fastener comes loose, you might hear a rattle. If a press-fit bearing slips, you're looking at catastrophic machine failure. The high strength (Source: Henkel Loctite datasheet, 2024) justifies the cost for those applications. I always confirm with the requester: "Is this for a threaded part or a press-fit assembly?" It saves a lot of back-and-forth.

2. "What's the deal with Loctite Go2 Gel? Is it just thicker glue?"

Sort of, but that thickness is the whole point. The conventional wisdom is "liquid flows better, so it's better." My experience in a busy plant suggests otherwise. Go2 Gel is for vertical or overhead applications where a liquid would just drip off before it cures.

Think about sealing a fitting on the underside of a machine. With a liquid, you're fighting gravity. The gel stays put. It's also way less messy for the maintenance team to apply (note to self: fewer complaints about sticky tools). It doesn't replace all liquids, but for the right job, it's a game-changer for application control.

3. "How do I remove something bonded with a high-strength product like 638? They say it's 'permanent.'"

This is a big one. You should never assume something labeled "permanent" can't be serviced. The key is knowing the removal method before you apply it. For most high-strength threadlockers and retaining compounds, disassembly requires localized heat.

According to Henkel's technical guides, heating the assembly to about 500°F (260°C) will break down the adhesive's bond. Always verify the base materials can withstand that heat first.

I learned this the hard way. We used a high-strength product on an assembly we thought would never need service. It did. The tech spent half a day carefully heating it with a torch because we couldn't just wrench it apart. Now, my checklist includes: "What's the planned disassembly method?"

4. "My requester mentioned 'primer.' Is that a separate product I need to order?"

Sometimes, yes. This gets into surface preparation territory, which isn't my expertise as a buyer. What I can tell you is that primers (like Loctite SF 7840 or Primer T) are used on inactive surfaces—certain plastics or metals—to make the adhesive cure properly.

I don't try to guess. When I hear "primer," my question back is: "Can you give me the specific product number, or should I connect you directly with the supplier's tech rep to confirm?" Skipping the primer because it "never matters" was the one time it mattered for us. A bonding job failed, and we had to redo everything. A $30 bottle of primer would've saved $400 in labor and downtime.

5. "How do I make sure I'm getting the real thing and not a counterfeit?"

This is a real concern, especially if you're price-shopping online. I stick to authorized distributors. The price might be a few dollars higher than some random Amazon seller, but it's not worth the risk.

Signs of potential counterfeits include blurry labels, misspellings on the packaging, or prices that seem too good to be true. Henkel has resources on their website about identifying genuine products. My rule: if the vendor can't clearly state they're an authorized distributor, I move on. The cost of a bond failure far outweighs any tiny savings.

6. "What should I ask the vendor before I place the first order?"

Here's my shortlist:

• "What's the shelf life, and do you rotate stock?" Old adhesive won't cure right.
• "What's the lead time for this specific item?" Some specialty items aren't shelf stock.
• "Can you provide SDS sheets and technical data sheets with the invoice?" Our safety and engineering teams need these on file.
• "What's your return policy on unopened, misordered items?" Mistakes happen, even with the best checklists.

Getting clear answers to these upfront has saved me countless headaches. The vendor who's vague on these details usually causes problems elsewhere. Five minutes of verification beats five days of correction later on.