# Coating system for rusty structural steel in stairwells



## PNW Painter (Sep 5, 2013)

One of my relatives owns an apartment building where the structural steel in 4 stairwells (about 20 total floors) needs to be painted. Although they are interior stairwells, the walls have openings so the steel is exposed to UV and small amounts of rain.

Here's a few images of the stairwells and the rust that is typical throughout. The stair treads are concrete over a steel structure.


























After talking with my SW Rep and a Manager of an SW industrial store I've been given these product recommendations.
- Primer - Kem Kromic
- Top Coat - High Solids Polyurethane, Macropoxy, Acrolon and Urethane Alkyd Enamel 

If this was your project how would you approach it? What coatings would you spec? 



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## racx (May 2, 2015)

Macropoxy does not do well with uv exposure but it may be limited. Kem Kromik is a good primer but man wear a repertory it will fume up the whole place, not to mention it's xylene based so you have a chance of it reactivating the previous coating. 
The truth is without removing the rust you won't get full life out of any of those coatings which are very expensive. Now to your question out of those recommendations if you are not removing all rust use a coat of macropoxy to lock everything down then top coat with urathane. Acrolon does not have a very long pot life so would forget that maybe the enamel would be best.


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## racx (May 2, 2015)

Forgot to add all of these products and reducers/cleaners for these products produce pretty tough fumes as you mentioned it being in a apartment building


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## PNW Painter (Sep 5, 2013)

Racx, thanks for your advice! I appreciate that you mentioned wearing a respirator because it seems as though PPE protection is an afterthought for so many. 

My plan is to brush and roll all the steel because the amount of masking it would take to spray isn't worth it. The short pot life of Acrolon would be an issue so that's out. At this point I'm leaning toward the Urethane Alkyd Enamel as a top coat and the Kem Kromic as a primer.

My plan of attack for removing the rust is to use scrapers, orbital sander with 40 grit and wire brushes on grinders, drills and by hand. Due to the tight spaces and size of the project complete rust removal isn't possible without blasting everything. 

Although the fumes will be an issue, the stairwells get excellent air circulation and are only connected to indoor common areas in a couple places and those are at the bottom of the stairwells.


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## Oden (Feb 8, 2012)

Just use a alkyd. Industrial enamel, whatever.
One coat is good. 2 coats is better.
Finish right on it. I wouldn't worry about it a little bit.


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## Lambrecht (Feb 8, 2010)

Use Corotech 100% Solids Pre-Prime then topcoat with an acrylic. I have a pic of a roof that I just finished using this system. I topcoated with Rust Scat Acrylic Semi-Gloss. No prep was done to the roof ie no cleaning, or grinding. The roof was heavily rusted and was last covered with aluminum paint. The pre-prime had a little bit of a sweet smell but not enough to bother anyone. I would not use Kem Kromic unless you want a bunch of sick tenants that smell will seep into the apartments.


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## Gracobucks (May 29, 2011)

I would use a rust converter after prep and prior to painting.


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## Oden (Feb 8, 2012)

That steel isn't even in bad shape. You hardly got to do anything to it. Some heavy sandpaper on a sanding head will get at most of it just fine. What's left by hand. More than that is a waste of time IMHO.

A dedicated primer is a backward step too, different color, different sheen, ur going backwards. A alkyd finish is all u need there.

I'm curious. Where is the handrail? That can't be a operating stair way in a apartment building is it open for use? I mean there is a rail there kinda but where is the spindles or whatever underneath? Ain't no way that thing would pass a inspection here. There's nothing at all to stop somebody specially a child, or a drunk haha, from falling between the handrail and the stringer. What are they working on it? Must be midstream of getting replaced? So the tower is shut down anyhow, or it should be.


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## I paint paint (May 4, 2014)

The concrete treads are raw and not getting coated?

Or they are painted and getting re-coated, just like the steel?


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## journeymanPainter (Feb 26, 2014)

I would scrap and sand all the rust and rust bubbles, then hit everything with a red oxide, scuff sand, then breakthrough (because it's strong, and dries quickly)


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## Stretch67 (Oct 7, 2013)

If your going the same color, slop on a coat of SW DTM Alkyd or IE like Oden said. Put on heavy, it'll go for sure 10 years maybe 15 before it looks like it does now. Unless there is grease or something, don't even bother with the prep. It looks pretty clean, dry and dull. Just keep ur putty knife with you and if you run into some loose stuff just knock it off and keep moving. 3/4 nap mini roller and a brush.

If u wanna monkey with the epoxies, just about any Novolac will do the job, of course it'll have to be topcoated. Go for the one with the longest pot life. But IMO, that's the wrong application. This isn't a water tower or a bridge.

Maybe one of the newer Urethane modified alkyds would be the ticket. Maybe retain the sheen a bit longer. But I haven't tinkered with em yet so not sure. Either way, I don't see a need for more than one product here.


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## PNW Painter (Sep 5, 2013)

Thanks for all the advice! I've gone ahead and ordered Kem Kromic to prime areas where the rust is the worst and SW Pro Industrial Urethane for the top coat. After weighing the pros and cons with the owners, they felt that the Kem Kromic would extend the life expectancy of the coatings, which makes the additional cost worthwhile. 

The color is also changing to Backdrop (SW 7025), which is a neutral gray. 

Oden, it's amazing that the handrail doesn't have any spindle's to stop someone from falling between the handrail and the stringers. It doesn't meet current standards, but from what I've been told it gets a pass due to the age of the building. Hopefully they'll address this at some point, but who knows.

The concrete treads already have a coating, but I've got no idea what it is. The owners are tentatively planning on re coating the treads and concrete walkways next year.


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## painter1986 (Mar 19, 2012)

How did the project turn out? I have something similar and have been curious about materials.


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## PNW Painter (Sep 5, 2013)

We had to postpone the job till next summer. By the time we were able start it was too late in the season and it wasn't worth the hassle of using heaters to get the metal up to temperature. 



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