A couple of weeks ago I needed to remove the paint from several parts, and spray-on chemical stripper seemed like just the thing to use. I hadn't used paint remover in a long time, so I did a bit of research first. I found that most commercial paint removers use Methylene Chloride or a variant as the primary active ingredient. Permatex, Aircraft, and Zip-Strip brands all have it at the top of the list of ingredients.
Among the stores in my neighborhood, only Permatex came in a spray bomb. Aircraft brand also comes in spray cans, but the hardware and auto parts stores around me only had the brushable type. From what I saw online, the Permatex spray-on is a smaller package than Aircraft, which seemed better for my small project.
I bought a can of Permatex at NAPA and I was ready to go. I stopped at my buddy's house on the way home to check in on his project. When I told him what I was up to, he said he'd recently stripped some paint w/Citristrip, a citrus-based product that's biodegradable and not nearly as poisonous as Methylene Chloride. He said it worked great, and smelled good, too.
This seemed like the perfect opportunity for a comparison test. Here's what I discovered:
The can of Permatex has lengthy instructions in fine print, describing its use and the safety precautions you should follow and the horrible things that can happen if you do not. I saw very similar language on the can of Aircraft stripper.
After checking to see what was downwind, I sprayed it on some parts outdoors. The paint lifted almost immediately. It's pretty stinky. I got a little on my wrist and it stung, so I washed it right off. Since the parts were small and the instructions didn't specifically say not to, I rinsed them off in my mud room sink. Quick and easy. But if I had been dealing with larger parts or larger amounts of stripper I would not have brought this into the house. I've also read elsewhere that this stuff really shouldn't go into the storm drain or sewer.
The can of Citristrip says that it's made from oranges, has no Methylene Chloride and is biodegradable. The ingredients list includes Dibasic Esters, N-Methyl 2-Pyrrolidine and hydrocarbon propellant. Though there is still strong language about using adequate ventilation and keeping it off of yourself, the warnings don't seem quite as dire as with the Permatex. It smells better, too.
I sprayed it on some parts outdoors. Unlike with the Permatex, nothing happened immediately. But the instructions say that it can take from 30 minutes to 24 hours for things to happen. I set the pieces aside and went on to other tasks. When I looked again the next morning, the paint had lifted nicely and it washed right off in the sink. This was against the recommendations, which say to let the residue dry outdoors before disposal. But the label also says clearly that it is biodegradable, so I don't feel too bad.
The bottom line is that both worked equally well in removing the old finish completely. Permatex works much faster than Citristrip if you're in a hurry. But if you don't mind waiting for it to work and want to ease your conscience just a little about the nasty sh*t you're releasing into the environment, then Citiristrip might be your choice.