When cleaning surface rust, should the table become completely clean in the end?

[Michael Yadfar]

So I unwisely kept the cast iron surface unprotected on my new Grizzly band saw I got this summer, which is in my unprotected-from-the-outside-air shed shop. When I used the saw frequently in the summer, I didn't notice any rust issue, but I haven't used it in a few months and I came to it today with a coating of surface rust. Anyway, I'm using WD40 and a scotchbrite pad to clean this table, and after about a half hour of serious elbow grease, you can still see rust and the comparison of the clean part of the table under the fence and the rest of the table. I'm wondering if this table should be completely brand new clean before I wax, or if this is expected. If this has to be brand new clean, I don't know what else I can do!

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[Brian Henderson]

You're never going to get it back to looking brand new but it's a tool, it's supposed to be used, it's not supposed to look new. There are a lot of ways you can do it that are easier and quicker than elbow grease. You can use a ROS with a Scotch Brite pad and it will take off rust very easily. WD-40 or mineral spirits work well here. If you're careful, you can use Naval Jelly which will just eat through the rust in a jiffy, but you want to make sure you remove all of it and it gets into cracks and crevices and is hard to get out so be careful. You can also use high grit sandpaper, starting in the 400 range and ending up around 2000 grit and it'll be incredibly smooth. Treat with Boeshield T9 or just Johnson's Paste Wax and you'll be golden.

[Bruce Page]

You can apply the wax now or clean it up more and wax. It's personal preference.
Which pad are you using? The Scotch Brite grey pad can be aggressive and still leaves a nice finish. The ROS will speed the process but is very messy.

[Brian Henderson]

You can apply the wax now or clean it up more and wax. It's personal preference.
Which pad are you using? The Scotch Brite grey pad can be aggressive and still leaves a nice finish. The ROS will speed the process but is very messy.

That's why I said "or just wax", wax is the last step regardless of what you might apply underneath it. As for the pad, it depends on what you're going for, there are several different grits that can be used, depending on how bad the rust is. There's an orange pad that's more aggressive but you'll want to follow it up with the gray one before going even finer with sandpaper. I got a cheap paste wax buffer from Harbor Freight and it actually does a really nice job buffing out the wax at the end, it leaves things slick as mercury.

[Michael Yadfar]

I'm using the blue scotchbrite pad. I have Johnson's paste wax on hand that I plan to use, but I just wanted to see how acceptable that surface is. I'm not new to woodworking, but I'm new to machine maintenance, as the shop I've worked in actually had a maintenance service, and the shop was properly insulated and climate controlled so rust wasn't an issue. So I'm starting to get a feel for this.

[Jack Gaskins]

If it were me.......I would use Evapo rust remover, get it from Autozone. poor on and let set for six or so hours then wipe off. Sand/scuff top wipe off, then go to walmart get a bottle of Barkeepers Friend in the liquid squeeze bottle not the powder. Wipe on small areas let set ten or so minutes then wipe off. Then wipe down top with mineral spirits dry and wax. I also used a cup brush on my grinder and ran across the top.

Jack

[Kevin McCluney]

As indicated by how rust-free the table is where the fence was positioned, cover the table when not in use and that'll help reduce rusting.

[Shawn Pixley]

Directly to your question, if this were my table I would keep cleaning until I couldn't see where the fence was. Evaporust, oxalic acid, or green scotchbrite & WD40 all work. I would clean up the edges as well.

After cleaning up the rust, wax, Boeshield or other protectant should be applied. Then cover the table when not in use. I use a furniture pad for the table saw. I cut a piece of thin plywood for the band saw.

[Michael Yadfar]

or green scotchbrite & WD40 all work. I would clean up the edges as well.

Wow, I just figured out my issue and it's a bit embarrassing. I thought scotch brite was scotch brite, didn't know there were different ones and I was using blue non scratch stuff. I just found a green one laying around and it cleaned the surface to brand new in like 30 seconds. The sides are painted so I won't be doing those

[Keith Weber]

"After" pic?

[Bruce Page]

Wow, I just figured out my issue and it's a bit embarrassing. I thought scotch brite was scotch brite, didn't know there were different ones and I was using blue non scratch stuff. I just found a green one laying around and it cleaned the surface to brand new in like 30 seconds. The sides are painted so I won't be doing those

Well, as I asked in post 3, "Which pad are you using?"...

[Michael Yadfar]

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Not the best pic, but here's "after"

[Howard Acheson]

Keep in mind that rust actually removes part of the surface of the metal object. You can never replace what has rusted away. Even with vigorous cleaning and sanding, some discoloration will remain.

As a preservative, nothing is better than Boeshield. Apply it per the instructions. Wax is not a very good preservative as is does not do a good job preventing water vapor from reaching the metal surface under the wax. Wax works fine to repel liquid water but does not work well with water vapor.

[Michael Yadfar]

Eventually I probably will get a rust prevention product, especially with the type of work environment I'm currently in. Right now I just started up my project again to insulate and seal up the shed that I started in the summer. I hope to get a dehumidifier in there, and at least prevent extreme temperatures. The good thing though is that I only spent about $4,000 on my planer, jointer, table saw, miter saw, and band saw. Once I get a better shop these will all likely be upgraded, but I still want to keep these in good condition for resale value and if I still want them as smaller tools. Now I understand the importance of humidity control once I get around to building my own shop years down the road

[Keith Weber]

Since I work in China, and my shop is in the US, it can be unattended anywhere from 2 weeks to 3 months (sometimes, in the winter) at a time. I have a lot of cast iron and unpainted steel in my shop. In the metal shop, it's a little easier to keep everything well-coated with oil, but you don't want that in a wood shop. I find that the best thing I do to prevent rusting is to keep a little heat on when I'm away. If I keep the heat on in my shop at around 45°F, it costs a bit more in utilities (as opposed to leaving it unheated), but my rust problem goes away.

The air always has a dew point. The dew point will change with the weather on a daily basis, as will the temperature. On a foggy day in the northeast, the temperature and dew point will be the same. In Phoenix or Vegas, the dew point will be much, much lower than the temp. You can still find Ford Pintos down there -- something that went extinct decades ago in the north, though salt on the road was probably a bigger factor than humidity. If you cool air to the dew point, you'll see visible moisture in the air.

The problem comes with a fairly rapid warming of the outside air temperature, say in the passing of a warm front. Yesterday, it might be 30°F, with a dew point of 25°F. After the warm front goes through overnight, the temperature might be 42°F with a dew point of 37°F. Still okay, because you've still got a 5° spread between the temp and dew point. The problem, though, is that since your 1500 lb, cast iron jointer is not going to warm up as fast as the air did, as it will tend to retain its temperature due to its mass. So now your jointer is, say, 33°F and the dew point of the air outside is 37°F. If you open up your shop door and allow this outside air to come into contact with your jointer, the jointer will cool the air next to it to below its dew point, and you'll instantly get a layer of condensation all over your nice, shiny jointer. The next day it will have a nice orange layer of surface rust for you to look at on its unpainted surfaces.

By keeping the heat at 45°F in my shop, my tools will not be cold-soaked, so the condensation issue will not happen. My tools are happy, which makes me happy. The 45°F figure is not a hard number. It's just my compromise between winter dew point temperatures and heating costs where my shop is. Obviously, as it gets well into spring time or early summer, there can be warm, humid days with a dew point above 45°F. On those days, you have to throw on some more heat or keep your shop doors closed to keep the humid air outside.

You might think, well... if that's the case, I just need to seal the shop, so that no air gets in, and then I won't need to heat the shop. That is true to a point. A couple of problems with that. Firstly, it is almost impossible to seal a building air tight, so eventually the dew point inside will slowly change as the outside air seeps in. Secondly, even if you could seal the shop completely, if the temperature drops far enough, you could still reach the dew point of the air trapped in the shop. You then have a major humidity problem that will rust everything inside your shop that is not painted. It'll be like a sealed bag of bread that you put in your freezer. All the moisture inside the bad condenses and eventually turns to frost. Vacuum sealing, as you know, makes stuff last a lot longer in the freezer. If there's no air, there's no moisture in it to condense. That's why the area under your bandsaw fence did not rust. There was no air in contact with it, so no moisture.

Sorry for the longish post. Bottom line is that a little heat goes a long way towards keeping the rust away.