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Clear finish for steel door?

Quickstart:
     Although it's possible to spray or brush a clearcoat onto bare steel, it probably won't prevent rust even for indoor exposure for too long, and it won't be satisfactory for outdoor use.
     Read on, join in ...

Q. I am trying to seal an unfinished mild steel entry door to my house with some sort of protective clear coat. I have been received varying suggestions, ranging from "it cannot be done successfully" to "you can use a spray can of lacquer from a hardware store." I am concerned with rust, the degradation of the clear coat under sunlight (it is an exterior door), durability of the finish, and appearance (I am essentially trying to achieve the look of an unfinished steel door).

Any suggestions or advice as to a finishing solution would be much appreciated. Thanks! ⇦ Answer?

Brass Wire Cup Brushes

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(affil link)

Q. I have stripped all the old paint off the inside of the steel door to my apartment, and I like the look of the bare metal. There are little spots of rust that I've been able to get off with a brass drill brush.
Once I get all the rust off, what coating can I use so that the door a) won't continue to rust and b) will give the door a clear matte finish? Is there a particular sort of polyurethane that's good for steel? Also, is it important to buff the metal with a jeweler's rouge ⇦ on eBay or Amazon [affil link] compound first? Thanks for any tips you can offer.

A. Hi, Allison: your inside door is much more practical to clearcoat than Jerry's entry door :-)

Spar Urethane


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(affil link)

Consider the way automobiles are painted for their exposure and why. First, every edge is turned or sanded so there are no places moisture can accumulate. Home doors are not built that way, and there will be wet areas around the hinges on exterior doors. Second, a good part of the metal on a car is pregalvanized (coated with zinc for sacrificial protection); if your door was pregalvanized, that coating is not transparent and will be gone by the time you sand the door. Automobiles are phosphatized, which is a coating that not only helps paint adhere, but evens out galvanic "hotspots" (areas that due to machining operations and stresses are more active and rust-prone). This is not a transparent coating, so you can't have this on your door either. Then automobiles are electrocoated with a primer; it's not transparent so it can't be on your clear finished door. Then cars are painted, then they are clear coated.

So, when you want a clear coat finish on a door you leave out galvanizing & phosphatizing & electropriming & painting and rely on just a clear coat to keep the steel from rusting. A 2-part automotive clearcoat is the most reliable, but don't be surprised if it doesn't work quite as reliably and as much to your satisfaction as we'd like. But exterior exposure in a humid area is much more problematic than interior exposure in a dry or air-conditioned area.

No, you don't need to buff it first unless you prefer the buffed appearance. Best of luck!

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

UV-Resistant Clearcoat

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(affil link)

I am amazed at the way almost any question posted on the internet can illicit intelligent-sounding "can't be done and here's why" responses. That drives me nuts.

Clear acrylic spay from a can works very well in this situation.
Basically, it is what's used on automobiles. Comes in gloss to dull finishes. Apply several coats. Note that painting a door may require several cans.

dirk blaze
- West Chester, Pennsylvania
January 25, 2010

Thanks, "Dirk". I didn't say it can't be done ... of course you can spray anything. It's quick and easy, things usually don't have to last forever, and life is short -- so your side of the discussion is appreciated!

I have yard art which I spray that stuff onto every year or two. It's a practical way to prolong its life when you don't mind frequent re-dos, don't need things rust-free, and aren't worried about the runny look of partially-peeled coats over a few years.

Still, I explained why car manufacturers spend the money to do all those steps that I described instead of doing it your way. It's why unpainted bar-b-q grills are always stainless rather than clearcoated plain steel; it's why appliance manufacturers use expensive stainless steel rather than clear coated plain steel even for indoor use.

I've supervised corrosion tests for many different finishes and can tell you that people who try to keep bright bare steel from rusting outdoors by simply spraying on a clearcoat -- any number of layers of it -- will discover its limitations really quickly :-)

My opinion is only my opinion, but at least it's from a real person with some metal finishing experience, whereas yours is posted with a fictitious name :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

A. I'd like to second Mooney's original answer, the reason it was 'intelligent sounding' is because it is. He did not say it could not be done.

I'm a professional furniture designer / maker with tons of experience in interior architecture and specifically finishing. It's what makes my work shine.

I have acrylic coated, wax coated, poly coated, you name it, and many times for clients who want 'that steel look'... and for those of you who eschewed chemistry early in life it is a fact of life that no polymeric (paint) coating is / or stays waterproof its whole life. Nearly all coatings, (wax isn't even a 'coating' in this sense) allow molecular water through it's pores. Oil based coatings less so, epoxy based coatings even less so.

Naval Jelly

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(affil link)

The reality is, it WILL rust under any coating, dependent on the ambient moisture, hence galvanization. What you have to do, but only if you want to DELAY this, is remove all rust physically, a wire brush is only enough for very superficial orange rust. Rust makes layers, you need to get UNDER and remove all layers, a scraper is cheap to open the rust pockets along with a twisted wire cup brush on a grinder (brass won't cut it on bad rust, too soft) .

Then, you must deactivate the residual rust chemically with Naval Jelly.
or a similar product that converts that "Rust that never sleeps" into a non active form.

If there isn't ANY rust (and I mean NONE), which is highly improbable, then just paint the damn thing.

Then, put whatever product you want on it. Epoxy will shine, but last a Really long time against rust, a NON-thinned polyurethane or a NON-thinned Acrylic are pretty good too. Wax is just eye-candy, it is very porous to water vapor.

Get all the rust off, be o.k. with light rust re-forming, enjoy your awesome door, and don't worry about anything. Its just a door, and you are a rebel against paint, remember?

Sef Pinney
- Loveland, Colorado, USA

Ed. note: Thanks Sef!

A. I found your letter because I have the same problem. I, too, am seeking a solution to the problem. I have some observations you might find helpful. For interior work wax is the best bet. Any rust that pops up can be 00 steel wooled ⇦ on eBay or Amazon [affil link] or Scotchbrighted (is that a word?) off then waxed again for a seamless finish. This also works on protected exterior work. The problem with hard finishes is the UV resistance. They break down. The biggest problem is that if you ever get water behind the lacquer it will turn milky or rusty. Then the only way to fix it is to remove all the finish. If you wax, you will never get paint to stick later ... Something to think about.

Ludwig Schweinfurth
ornamental iron fabricator - Weatherford, Texas
2006

Microcrystalline
Museum Waxes

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(affil link)

Q. I too am looking for a clear finish for steel plate. I like the wax idea but I am cladding a fireplace with this, so I am not sure a wax would work. ⇦ Answer?

Q. How do I apply a wax finish to a fireplace (plain/raw steel)? What kind of wax do I use? Thanks. ⇦ Answer?

Q. I've read this thread and am deciding between the wax and acrylic. This is for an interior ceiling fan, where I also like the raw steel look. I've brushed off most of the rust with a brass wire brush ⇦ on eBay or Amazon [affil link] .

What type of wax? Will this feel wet to the touch when finished and attract lots of dust?

Thanks, Brian

A. Hi, Brian. If your home is air-conditioned, or at least not muggy, not much corrosion protection is needed. The wax should be dry to the touch (it's what museums use for their metal objects).
But wax is much thinner than a clear coat, and is something you need to repeat with some frequency, especially if you don't have museum-level environmental control. Since that's probably not convenient for a ceiling fan, I think the clear coat may be more practical, but either will work. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Q. Hello,
I bought some NEW raw steel furniture legs that have no rust on them. They will be used for lightweight interior furniture. How effective is shellac as a sealer?

I am not concerned about how shellac will add color, but only with its ability to slow or prevent rusting. I have already applied it to the legs so I know that it will, in fact, adhere.

has anyone ever tried this?
Mark

A. Hi, Mark. I haven't tried it, but I do see a technical paper on water-thinned shellac as a primer for iron and steel, so I suspect that it will be fine for indoor use. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Want to polish shipping container home to keep it cool

Q. I'm planning to build a shipping container home and would like to strip all the paint from the outside walls and apply a finish to the bare steel to reflect a lot of the tropical sunlight and heat. They're made from Corten steel which doesn't rust but it does oxidise which not only looks like unsightly rust but also negates the reflection of sunlight. Since I plan to use about 5 containers, it will be expensive to use Klear Kote and I'm looking for a cheaper but durable alternative. I'll be putting solar panels on the roof so anything that doesn't require frequent repainting would be nice. To make it more challenging, I'm also planning to harvest rainwater (non-drinking, but used for bathing and washing wares) from the roof, so it shouldn't be too toxic. If there's no easy solution, I can always leave the roof painted and strip the side walls of paint. Any suggestions will be appreciated.

A. Hi, George.

If you want the bright metal look for aesthetic reasons, that's fine. But if you think it will reflect heat instead of absorbing it, please touch the shiny metal bumper of a truck on a hot sunny day before proceeding with the project. Solar collectors are chrome plated to increase their capture of the sun's heat :-)

Bright white paint is more heat reflective than shiny metal. This is probably confusing, but the difference between a mirror and a bright white wall is diffusivity not reflectivity. It's not that the white wall reflects less light than a mirror, but that it scatters the light in every direction instead of maintaining a focused image. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Q. I'm sure what you're saying makes perfect sense, Ted, but I went Googling further and found this -

"What is an everyday example of a good reflector of heat?

A light colored or highly polished metallic surface will reflect a lot of heat (which is primarily infrared radiation). Some people in sunny places put a folding windshield screen up inside their car. The best ones have what looks like shiny aluminum foil on them to reflect the heat."

Read more, wiki.answers.com: What is an everyday example of a good reflector of heat"

If white paint is as just good as bare metal for reflecting heat, I shall use the white paint as it's a lot simpler and cheaper than clear coating the containers.

Many thanks,

George

A. Hi, George. The absorption of heat from sunlight by aluminum is way less than by polished steel or stainless steel for reasons that are beyond my pay grade -- "drude electrons", etc. -- but you really can't compare a polished steel shipping container to an aluminum car shade. But to compare polished steel to steel that is painted white, please see:

en.wikipedia.org/wiki/Cool roof

and azcoolroof.com/downloads/Resources/Article%20Laboratory%20Testing%20of%20the%20Reflectance%20Roofing%20Materi.pdf, "Laboratory Testing of the Reflectance Properties of Roofing Materials" -- especially page 7.

White paint is a lot better than "just as good". It absorbs as little or less heat from the sun in the daytime, but it emits much more at night.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Ed. update: The above link is broken. Thankfully, the Internet Archive preserved a copy here  🙂

Excellent, Ted! Big thank you. I'm completely convinced. What I thought was a simple matter has turned into a most interesting discussion on cool roofs among my friends here.

Thanks and blessings,

George

! My pleasure, George -- I learned at least as much as you from our googling together. Come February, when it's below zero here, I'll be thinking of you and your friends trying to escape the heat  🙂

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Q. I have a basic steel wheel that I am using as a base for a coffee table. The question remains, Use a wax or clear coat to prevent rust and corrosion. I want to see the steel and not paint it any color. I want to keep the carpet the table base will sit on safe. Is a wax going to get on the carpet. Is a clear coat on a 50 lbs solid steel wheel going to get on the carpet. There are a lot of intelligent comments on this site. I appreciate any advise
PS
My Google search term: clear coat unfinished steel-you were the number two search. This is how I found you. Any help is appreciated

A. Hi Dan. I don't know if buffed wax will rub off at all onto the carpet, but if you don't buff it to death to make sure you haven't missed a nook or cranny, it does sound possible ... so clearcoating is probably better for you.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Q. We have just finished remodeling our only bathroom and are searching for storage furniture to add to the room. We have found two different sets of raw steel pieces that work dimensionally, one set that is vintage and the other made to look vintage. I'd like to know if this is going to inevitably going to be a problem of oxidation? We added a pretty powerful fan to take out moisture just above the tub/shower but there will no doubt be residual moisture in the room. Can anyone tell me if this is a lost cause or if there is some sort of treatment we can apply to stop the oxidation? The cost for these is pretty substantial and will only work for this space so we'd prefer not to find ourselves in the hole on something we could have avoided. Thanks so much-

A. Hi Chad. Paints and clear coats are much more rust resistant than bare metal, so if they are involved in either of the finishes, it will probably be okay.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

Q. I'm looking for a reliable, field applied sealing method for hot rolled sheet steel. I have 4 interior doors and frames that will be touched by lots of people. I like the fingerprints, etc. but I'm concerned about rust over time.

I really want to keep the hot rolled look, so a clear sealing method is desired. I've heard that butchers wax will do the trick, but is high maintenance. Any other suggestions or references would be great.

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