If you’ve been around a while, you’ve heard the old saw: Once you stick stuff together with 3M 5200 (or any of the other one-part polyurethanes or polyether adhesives on the marine scene these days), there’s no going back. Not unless you want to tear your boat up or flat-out destroy somethin’. And yeah, there’s often a lot of truth to the various saws you hear from folks, which I guess is why the darn things (the saws, not the folks) get to be old.
But hey, sometimes, you really,really, really need to break the fabled bond that can’t be broken. Or you need to remove a chunk of poly-insubordinate goop that simply can’t, can’t, can’t remain where it is. And, should that desperate day arrive for you, I’ve got a whiff of provisionally good news, based on what I recently discovered while attempting the damage-free removal of two thick strips of 3M Fast Cure 4000 UV polyether adhesive from the transom of a small sailboat.
Here’s the deal. While 3M recommends removing or de-bonding Fast Cure 4000 with a knife, razor blade, or some other mechanical device—a rocky route typically strewn with scratched or chipped gel coat and a host of other ghastly befalling’s—there seems to be at least one product on the market today that does the job chemically, without engendering a whole lot of misery.
Notice that I say one. I cranked up this project with an ulterior motive. While I, of course, wanted to accomplish the adhesive-removal task, I also wanted to parenthetically compare two de-bonding agents (see photo above) that are fairly popular these days, namely West Marine’s Anti-Bond 2015, around for years now, and Un-Hesive (www.un-hesive.com), the new kid on the block. And guess what—only one product performed well. The other?
But before we get into all that, let me toss out three, worthy disclaimers. First, as noted above, 3M Fast Cure 4000 is a polyether, not polyurethane adhesive, meaning it is perhaps slightly different than, say, 3M 5200 but still wickedly strong and resilient. Indeed, once I’d removed the four quarter-inch bolts that secured the flanges of the (in my opinion, unsightly…hence my decision to remove it) outboard-motor mount shown at the beginning of this post, I had to discombobulate the mount, pull sideways on each individual stainless-steel leg, applying all my strength and weight (I’m a reasonably healthy, 165-pound, six-footer), and only then did each leg eventually pop loose, uncovering the strip of adhesive still clinging vengefully to the gel coat underneath it. Second, both Anti-Bond and Un-Hesive are advertised as polyurethane-specific. It’s conceivable that a polyether shootout did not give both products a fair shake. And third, directions for using the poor performer stated, “For vertical surfaces (like the transom of a small sailboat) cover with a piece of plastic to trap the liquid.” This suggestion seemed a bit iffy to me. I was concerned that leakage around the plastic pocket might somehow damage the sailboat’s gel coat. So I went instead with simply spraying one adhesive strip with one product and the other strip with the second.
Paranoid? Well, maybe. But the sailboat in question is virtually new and the products I was testing were untried and unfamiliar to me. Check out the above photo. To keep the boat’s gel coat safe, I went so far as to surround the two adhesive strips with a couple of layers of protective varnishing tape and, on top of that, a layer of plain ol’ duct tape.
I applied the Anti-Bond as directed on its spray bottle. Afterwards, I waited about 10 minutes (per directions on the label), and then began scraping with the end of a paint-stirring stick. The results were so encouraging that I hit the adhesive with a second liberal shot of Anti-Bond and found that, within maybe five minutes or so, I’d removed all the adhesive material I’d treated.
I applied the Un-Hesive in the same manner. I waited about 20 minutes (per directions on the spray bottle), and then began scraping with another paint-stirring stick as before. The results were discouraging rather than encouraging, even after I’d tried a couple more shots of the Un-Hesive product. At length, I decided to remove the second strip of Fast Cure 4000 with Anti-Bond instead of Un-Hesive and, once I’d begun, I completed the work in just a few more minutes.
The conclusions I can draw are limited. Will Anti-Bond remove or de-bond 3M 5200 or any of the other one-part polyurethanes? I don’t know. Will Un-Hesive remove or de-bond the same sorts of products? Again, I don’t know.
But believe me. If I have to remove or de-bond 3M Fast Cure 4000 UV (or any other polyether-type adhesive) in the future, I’ll go with Anti-Bond 2015. It produces a decent result, while doing virtually no damage to the surrounding gel coat. West Marine sells 1.5-oz. spray bottles of the stuff, by the way, for $19.99. An 8-oz. spray bottle of Un-Hesive will cost you $19.95.