How do I clean this brown gunk off my forms before the next job?

Cosmoline is a nightmare to get off aluminum once it sets up and gathers dust, but you definitely need to strip it before that first pour. If you leave that brown funk on the faces, it will absolutely ghost into your finish. It acts like a bond breaker in all the wrong ways and can leave nasty, oily staining on the face of the concrete that no amount of sacking or rubbing will fix later. Since you over-applied it, a standard pressure washer won't touch it unless you're running a hot water unit at about 200 degrees, and even then, it's a mess. Your best bet is a heavy-duty degreaser or a citrus-based solvent. I usually go for something like **mineral spirits** or a dedicated wax and grease remover. Spray it on thick, let it dwell for five or ten minutes so it can soften that waxy layer, and then use a stiff nylon brush to agitate the corners. Don't use a wire brush on the aluminum or you'll scratch the hell out of the faces and those marks will show up on every single wall you pour from here on out. Once you've scrubbed the bulk of it, hit it with a high-pressure rinse to blast away the residue. You'll know it's clean when the water stops beading up like a freshly waxed car. After they're dry, just hit them with your regular form oil or release agent right before you set them. The release agent won't penetrate that old Cosmoline, so getting back to the raw metal is the only way to ensure a clean pull. And for the future, if you're storing them long-term again, a light mist of a high-paraffin form oil is usually enough if you keep them covered. Cosmoline is great for shipping parts overseas on a boat, but it's overkill for a form trailer sitting in the yard. It's better to deal with the labor of cleaning them now than to have a client refuse to pay becasue thier foundation looks like it has tobacco spit running down the walls.

I did the same thing once thinking I was being smart. Mineral spirits work okay but what really got it moving for me was just straight diesel. I soaked a rag in it, wiped the faces down, and let it sit. The wax just melted right off. Then I used Dawn dish soap and a scrub brush to cut the grease before the final rinse. Whatever you do, don't let that run-off hit your new blue bins or the trailer floor—that crap stains everything it touches and stays sticky forever.

While the aforementioned hydrocarbon-based solvents are effective at breaking down the aliphatic hydrocarbons found in Cosmoline, you must ensure your subsequent cleaning process removes all trace residues, as any remaining film will adversely affect the surface tension of your release agent and potentially lead to localized 'bug holes' or surface voids. I have found that employing a heat gun to soften the thickest accumulations before introducing a high-purity xylene helps significantly, though one must exercise caution regarding the flammability of such vapors in a confined trailer enviornment. Furthermore, ensure you are monitoring the pH of any aqueous detergents, as highly alkaline cleaners can inadvertently etch the aluminum alloy and compromise the face quality.

So I tried the diesel trick someone mentioned, and it definitely melted that brown gunk right off. It was way faster than scrubbing with spirits. However, I’m still seeing a really greasy film on the aluminum faces. I’m worried about what was said regarding the release agent not sticking correctly. Has anyone found that a standard pressure washer with soap is enough to kill the grease, or do I need something stronger?