- Grey Scotch-Brite Pads (7448)
- Some sort of treatment such as…
Cast iron gets rusty. Period. You can take steps to help prevent it but you’ll still have to deal with it eventually.
In my case, I have a SawStop Industrial Cabinet Saw with an additional 10″ cast iron wing that has some rust forming on it. It’s not too bad but I should definitely do something about it. You can see a big greasy hand print right on my right miter slot. (How that happened is a long story but rest assured, our lights work now.)
Another mysterious rust spot. It isn’t too bad so it should mostly come off.
Removing The Rust
Some people prefer to use 0000 steel wool to remove rust, and it will do a pretty good job. Personally, I prefer to use Scotch-Brite 7448 pads. These are the grey pads, not the green ones you use in your kitchen. They are the same grit as 0000 Steel Wool but you can use a sanding block to apply even pressure over the entire pad. This is a lot harder to do with steel wool.
Next, I apply a generous coating of WD-40 to the entire table top. You want to let it sit for a while so it can penetrate the iron and start to break apart the rust and even some of the slight discoloration that cast iron can sometimes get. I will typically let it sit for at least 15 minutes but in this case I let it sit for about an hour and a half.
Technically, you can stop here. I find that no matter how much I scrub with shop towels I can never quite get all the WD-40 up. This leaves a slightly greasy feeling to the table top which can transfer to the material you are cutting. I find that the best way to clean this up is with denatured alcohol.
Protecting The Surface
There are many ways to protect the surface of cast iron tools. I’ve had good experiences with T-9 BoeShield or GlideCote, but I personally prefer using a furniture wax like Johnson Paste Wax, although MinWax and Renaissance Wax will work as well. I like Johnson Paste Wax since it is softer, which means it applies easier and also buffs out a LOT easier than either MinWax or Renaissance.
Use a fresh rag to wipe the wax off and buff it out. This can take some experimentation but the way I handle it is to use one rag to wipe the bulk of the wax off but I don’t worry about it looking good yet. You’ll still have some streaks and maybe a few missed blobs of wax. After that, I take another fresh rag and wipe it down to buff it out. You’ll notice that when you first start buffing it, the table will be slightly “grabby” with the rag. Just keep buffing. You don’t really need to apply much pressure or buff in any particular direction, just go back-and-forth for a while to build up some friction. You’ll find that eventually the table will get very slippery. That means you’re done and ready to move on to the next section.
That’s it. You’re done. You now have a nice slippery cast iron table top that won’t rust up as quickly (if at all). I like to repeat this process as needed, which may be every six months or every six years. It all depends on how you use your saw.
Also, it is a good idea to apply some paste wax to the exposed metal on the front tube where the fence rides back and forth.