Some notes on paint removal and clean up

I want to completely strip the South Bend Lathe down to the bare metal and then repaint it. This will mean taking out every screw and taper pin (more on those later) and then using some kind of paint remover to get down to the bare metal. I hate organic chemical strippers. They work great, but long ago I got sensitized to them by being cavalier about wearing gloves. Nowadays even a drop on my hand feels like a burning match.

So the first thing I tried was the somewhat famous "Mr. Muscle" oven cleaner. Basically this is lye and surfactants in some sort of foaming carrier. It works great, but is very expensive! Here are a bunch of parts sitting in a plastic bag after being sprayed down with the oven cleaner. The plastic bag keeps the moisture in and lets the parts "soak". NOTE: I stupidly left the brass plaque on the gearbox in this picture. It had already had all its paint worn off, but even so I ended up giving it a tough green patina that I had to remove. Also DO NOT PUT ALUMINUM IN OVEN CLEANER OR LYE! It will dissolve. Quickly!

South Bend Lathe parts in oven cleaner

After sitting for a day or two you can just wash the paint and old oil right off. I also found a cheaper but still heavy duty cleaner that is based on Potassium Hydroxide instead of the Sodium Hydroxide in the Mr, Muscle.  Even so, it costs a lot to do a whole lathe.

A better solution (pun intended) was to buy a few bottles of Red Devil lye at the hardware store and dissolve it in water in an old 10 gallon paint bucket. Be careful when you add the lye to start with cold water, and to add the lye SLOWLY! The reaction as it dissolves and hydrates generates lots of heat, and if you are not careful it can boil and spatter on you. WEAR LONG GLOVES AND EYE PROTECTION!

This gave me a cleaning tank I could dump parts into and forget about for a day or two. Pull them out, rinse them off, and they are good to go. I worked through all my lathe parts in a week or so. You do have to rinse them well, but the alkali solution means that things don't rust much. Also I ended up using a Phosphoric acid based primer which neutralized the lye and passivated the cast iron (since I knew I would not get to paint for a while). I even put all the hardware in there to clean up the threads and get rid of the old hardened oil. I punched a bunch of small holes in a tin can, put a handful of nuts/bolts/washers/whatnot in the can, and lowered it into the lye bath. A day later you just lift out the can and let it drain and then run warm water in it to wash off the lye. Works great!