Ronsonol is Naptha
Laika and Curt are both correct. Ronsonol (also sold as Zippo liquid lighter fluid in the USA) are 100% naptha, which is also known as Varsol in other places.
Naptha is a chemical solvent that has been used as a dry cleaning solvent, as Laika mentioned.
Butane is a gas - Ronsonol is available to recharge non-disposable butane lighters, but that's not what you use to clean shutters with.
Naptha is a hydrocarbon, like gasoline and jet fuel. Since it is used as a liquid lighter fluid, it is obviously flammable by design. Extreme care should be taken if it is to be used.
Here is how
I use naptha - I do not recommend that anyone else follow my practice, nor is this intended as advice. This is just how I do it.
I clean stuck shutters and aperture blades outdoors or in a well-ventilated area, away from all open flame. I pour out a small amount of naptha into a container like the lid of a 35mm film cannister and close the Ronsonol container, which I keep well away from my workplace. I use q-tips (cotton swabs) dipped in naptha to slowly clean shutters by directly swabbing and gently rubbing them with naptha-soaked q-tips. If the shutter leaves are stuck together, I press down ever so slightly while massaging them - this allows some fluid to run inside and between the leaves.
If the shutter is under tension (because it had been wound and fired, but had not actually worked), it may suddenly spring open as soon as the debris or yuck that's keeping it closed is cleared. So be ready for that. Otherwise, I just keep trying to wind and fire until it finally does.
On fixed lens rangefinders, the aperture leaves are usually behind the shutter, so once I get the shutter working, I keep cleaning it until the leaves are smooth and shiny looking, but then I use the "B" setting to hold the shutter open (a cable release with a lock works great here) and then I can get at the aperture blades. I give them the same treatment as the shutter, but they won't suddenly spring open. I find that when the shutter blades close, they pick up more dirt / naptha, so you do this process over and over again. It can take an hour or more per lens. Just be patient.
If I have been sparing in my use of naptha, the rear lens element will be clear, but if any has dripped, obviously it must be cleaned out as well. There are tools that allow you to remove the rear element from inside the camera (
www.micro-tools.com), and I have a couple of those, but generally, I just clean the inside of the lens out with q-tips and lens cleaner once I get the naptha out.
If a shutter is totally stuck, I might try 'flood cleaning' where you just douse the thing good and proper in naptha - but of course outdoors and well-ventilated. Then leave it sit for awhile. That might cure it, but of course you'll have to clean out the aperture blades and the inside of the rear lens element, since they'll have been soaked as well.
I have slowly gotten better results in recent years with these methods. I would say that I get better than 50% success rates. I find that by continuing to clean even after the shutter frees up, until the blades are bright and shiny, gives me a better overall fix - otherwise, the blades eventually tend to bind up again.
Shutter blades need no lubrication, and neither do aperture blades. Once they are clean and shiny, make sure they are dry of all naptha and button the lens up.
That's pretty much it. Works for me a lot of the time, but if that doesn't do it, then I either discard the camera/lens or plan to send it off to be properly done by a professional, depending on what it is worth to me. I recommend trying it on a cheap camera/lens first before trying it on an expensive/classic camera/lens.
Best Regards,
Bill Mattocks
