Rust prevention on cast iron

[Nick Mazzino]

This is my second summer in my shop.
Last summer I could not keep surface rust off the cast iron.

What do you guys use to prevent rust on your cast iron surfaces? I will lightly wet sand with mineral oil and 500 grit sand paper then put Johnson past wax on.
However, I was having to do this about once a month, sometimes more frequently.

My shop is a detached building from my house.

Looking for a better option.

Thanks,
Nick

[George Yetka]

I use glidecoat on the cast iron surfaces. If I neglect reaplying I use boeshield rust free on a scotchbrite pad. Surface rust comes right off.

The best thing to do is to get a dehumidifier going and set it at 45% or so. Since I added the dehumidifier I have had very little issues with rust

[Devon Prescott]

I live in a humid area (temp and humidity both in 90s most summer days). I did a thick lay down of Liberon Paste wax (I like the smell) on a big saw table. I do re-apply it after heavy use (rare for my TS these days). I don't know about Johnson's but people are saying that is has been re-formulated.

In MY shop its not the strait-up humidity but the falling and rising temps combined with humidity. A covering (tarp) seems to stop this process entirely for me - even for machines that I don't wax up. Your mileage may vary, of course.

[Jacob Mac]

I had the same issues last summer. I bought a dehumidifier for this year.

Otherwise, it is Boeshield T9 and paste wax.

[John K Jordan]

What do you guys use to prevent rust on your cast iron surfaces?

I have a Robland sliding table on my PM66 table saw. From the manual: "White talcum powder applied with a blackboard eraser rubbed in vigorously once a week will fill casting pores and form a moisture barrier."

I bought talc power from Amazon, the stuff made for billiards, not babies. I don't use it as often as they say, maybe once every few months.

JKJ

[Jacob Reverb]

My shop is in a barn along the coast where we get heavy, heavy dew almost every morning from about May until about October. I've tried waxes and goos and talc and just about everything else, but the only thing I found that would work reliably is a 50-50 mix of drain oil and kerosene, which I would wipe on at night and then wipe off in the morning before working. I've gotten weary of the wipe-on, wipe-off routine, and in another thread on this topic, someone suggested thinning down polyurethane to a wiping varnish viscosity and using that, so I tried it. It works great so far.

[Orlando Gonzalez]

Quite humid here in So. Florida. I have an air conditioned 12x18 shed that serves a my dedicated shop and I still have to keep the rust off. I spray WD40 on the CI tops and then use a RO sander with 220g on them. Wipe clean then spray with Boeshield T-9 or CorosionX. I then cover them with a cardboard piece or 1/4" plywood sheet. The cardboard and plywood are cut to the machine's dimensions.

[mark kosse]

I've said this before here but the best rust preventive I have found a a piece of cardboard. I recently dug out and sold a Delta 12/14 that hadn't been touched in 5 years and zero rust under the cardboard. Here in CenTex it can range from extremely humid to very dry and 10 deg to 110 deg, so lots of changes and my shop is unheated or cooled. I prefer shinny cardboard but any cardboard will do. FWIW

[Robert Engel]

Keeping a fan running at night will help.

Other than that, the more infrequently you use your machines, the more issues you will have with rust.

IOW - more woodworking!!

[Eric Anderson]

My biggest rust issue is sweat drips in the summer (and it's already summer in Texas). I usually use CRC 3-36 spray and very fine wet/dry Emory paper to sand out the rust spots at the end of the day (they appear within minutes). If not for the sweat drips, I keep my table saw covered with an old Gore-Tex mattress cover when not in use and that works great and don't really get much rust even in a uncooled garage.

[David Eisenhauer]

Johnson's Paste Wax for many, many years on all cast iron table tops. Prevents rust and slicks up the surface for ez gliding material through the blade.

[Jacob Mac]

So you guys just throw cardboard on your cast iron surfaces and no rust? Is it really that simple?

[tom lucas]

I rub in a light oil, like WD40 or 3in1. Then follow with talc (must not contain corn starch - real talc), rubbed in with an erasure. Then a coat of Johnson's paste wax right on the talc. I don't buff the wax off until I'm ready to use the tool. I just leave glazed over wax in place. Works for me. My shop is not heated nor cooled and no insulation. It's very humid here and this has worked for me. I do watch for rapid temperature swings combined with humid weather (usually late summer here). These can cause "condensation events" seemingly on some random piece of equipment in the shop. I'm betting that covers would prevent this altogether. I've never tried cardboard. I always worry the paper will absorb moisture and pass it to the iron.

[Charles Lent]

Rusting tools is a significant problem in shops that are not air conditioned and located in the Eastern half of the US. Keeping the humidity lower that about 50% requires a dehumidifier or air conditioner and the shop kept closed up as much as possible to keep the high outside humidity air out of the shop. Actually, another measurement of humidity is more important. "Dew Point". Warm air can hold more moisture than cool air. When warm moist air is cooled, a point is reached where the air can no longer hold the moisture that is in it, and some of this moisture begins condensing out of the air. This is the Dew Point of the air. This is why dew forms as the warm Summer air cools over night and dew forms in the early morning hours. The air temperature has dropped low enough that the moisture in it can no longer be held.

Keeping your tools rust free requires that you keep your shop air dry enough that the dew point of the air is way below the temperatures that the shop air will ever be. Let the shop air get very humid and then let it cool down without removing this moisture and if it reaches the dew point, you will have rusty tools. Waxing the surfaces will help prevent rusting, but keeping the air dry enough that you never reach dew point in your shop air is really the key to keeping your shop tools rust free.

My shop is about 6' above and less than 100' from a 250 acre lake. Tools left outside overnight in the Summer months will be rusty in the morning. But my shop is insulated, air conditioned, and has a vapor barrier. I do wax my larger cast iron tools, but mostly to make boards slide easily over them. I don't have rust problems in my shop, even if I don't leave the air conditioner running full time.

Charley

[Randall J Cox]

I have a Robland sliding table on my PM66 table saw. From the manual: "White talcum powder applied with a blackboard eraser rubbed in vigorously once a week will fill casting pores and form a moisture barrier."

I bought talc power from Amazon, the stuff made for billiards, not babies. I don't use it as often as they say, maybe once every few months.

JKJ

I use sometimes Johnsons paste wax and sometimes baby powder, both work for me in central calif with little humidity. The baby powder makes the shop smell nice... ha ha Randy

[Terry Wawro]

For most of my cast iron tools Johnson Paste Wax works great for preventing rust. Even left uncovered for months at a time. The only exception is my SawStop. Even with two coats of wax it will start rusting if you just walk past it with a cold can of soda. After awhile I got tired of the constant maintenance and decided to try something new. I stripped off all the old wax and cleaned the top with acetone. Then I sprayed on a heavy coat of CRC 3-36 and let it sit overnight. The next morning I rubbed off the excess with paper towels. Worked great. It's been over 4 months and still no rust.

[Mike Cutler]

I use a nice paste wax.Sometimes MaQuires, sometimes Fleet, sometimes Johnson's. All work equally well. The MaQuires is the easiest to apply, the Fleet is a marine paste wax and is more difficult.
When not in use ,all of my machine tops are covered with a layer of cardboard, scrap plywood, and those cheap moving blankets from Harbor Freight. This sequence in my experience keeps the moisture from being able to settle on that machine tops,and it protects them from me setting things on top of them, which I do as my shop is in my non climate controlled garage ,and sees multiple duties. I don't think there is a single natural fiber in those HF blankets,so they don't attract, or hold any moisture. For some reason, the jointer is the only machine that gets small "blooms",but they're easily wiped off.
If I keep up with this process, and wipe the machines down after use, I apply wax once, or twice,a year. If not, I'm out there with AeroKroil, transmission fluid, acetone, and a fine 3M pad. :( I keep up with it.

[Charles Lent]

Be very careful of using automotive waxes for any reason in your wood shop.

Many automotive waxes and polishes contain silicone. Silicone in a woodworking shop will cause all kinds of finishing problems when it gets on your wood or the projects that you make. You can't see it, until you apply stain or finish, and discover fish eyes (little spots where the finish won't stick to or the stain won't sink into the wood). Fish eyes are nearly impossible to remove once the wood becomes contaminated. The silicone soaks into the wood, so even heavy sanding doesn't always remove it, and no solvent seems to completely remove it either.

Silicone containing products have been banned from my wood shop, and I closely read the label of anything new that gets brought into the shop to be certain that there is no silicone in it. I replaced a workbench and burned several hundred dollars worth of wood and two projects that got contaminated with silicone many years ago. I learned my lesson the hard and expensive way and will not make that mistake again. Johnson's Paste Wax and Butcher's Wax are the only two waxes that I allow into my shop now, and I use either on my tool tables and cast iron for rust minimization and to make my work slide easily over the tables and along the fences. My automotive polishes and waxes remain in my garage at the opposite end of my home from my shop and are used only on my cars.

Charley

[Mike Cutler]

Charles

Thank you! I never thought to look up the SDS to find out what was in the wax. Turns out the Maguiars Paste wax does have a silicone type product in it.
I haven't had the issue you referred to with it, but I'm going to stop using it before I do.
Once again. Thank you.

[Jacob Reverb]

FWIW, if you do get finishing problems due to silicone contamination, I've found that a product called "Smoothie," used by auto body folks, works. You add something like 12 drops to a quart of finish, then proceed as normal.

I've also heard you can coat the fisheyes with shellac, then finish as normal – but unlike the Smoothie, I haven't tried that method.