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corten steel

silverlake

I want to use corten steel on a little commercial facade renovation project but am unsure of a couple of things...

Will raw steel sheet metal weather to the same end as corten? Is there any way to control the rust? The client likes the idea but is afraid her new sidewalk will get too discolored.

Any thoughts or tips are greatly appreciated....

 
Jun 23, 06 3:33 pm
mimo

I don't think raw sheet metal will weather the same, and if it does weather, it probably won't be as structurally sound as cor-ten. Contrary to most cases where you would think rust decreases the structural integrity of the material, Cor-ten is designed to become even stronger after weathering. If you are afraid of run off the only solution I have is to let it rust prior to installation. You can buy an accelerator to speed up the rusting process if you are in a hurry, and once you get the patina shade you want you can stop the rusting process with a sealant / clear coat. That way you don't have to worry about future run-off after installation.

Jun 23, 06 4:54 pm  · 
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newstreamlinedmodel

The point of the coreten is that it doesn’t need to be sealed, the rust reaches a stable point and it doesn’t completely degrade like regular mild steel would. In an exterior application I wouldn’t place a lot of faith in sealants unless you did a clear powder coat or something. With corten you probably will always will get enough rust run-off to discolor the sidewalk. Maybe you can workout a drain detail so that runoff is directed out of the way.

Jun 23, 06 6:03 pm  · 
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waxwings

you should search cor-ten threads, it's been discussed here at least once before. i agree with mimo, it's not going to rust the same. cor-ten is designed for the way it rusts however it will eventually perforate. you may want to hunt around the US Steel site, they have a fake cor-ten product (actually galvalume) and you'll see that they don't recommend cor-ten for architectural applications, and there's a discussion of the staining problem, yadda, yadda, yadda.

Jun 23, 06 6:06 pm  · 
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art tech geek

also, a thought on sealing oxidizing using powder coating - for it to work as designed - the material should be preheated in the powdercoating oven prior to spraying. its around 400f. if you see powder coating that is chalky discolored and a couple years old - odds are that the powder coater did not preheat the material. the thicker the material - the more expensive it is to powder coat. just hearing a nice price is a tip off........ a caveat to remember. if the powder coater give a warrantee of less than 10 years - I would be suspect.

on the fresh sidewalk- you could also prestain it using l m scofield lithochrome stains (or Kemiko or rareearth) - then its controlled and intentional, not accidental and irritating

yadda yadda x2

Jun 24, 06 11:24 pm  · 
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ichweiB

Parsons used cor-ten for a design-build in Brooklyn. It is a field house at a high school. The majority of it is cor-ten. I don't know where you are, but if you are able to get in touch with anyone there, maybe you can get some info.

I went a checked it out with the guy who heads up their design-build. From what I remember, they didn't let it pre-rust. With as much as they used, I was surprised that it didn't rust more.

Sometimes, the look is really cool; however, for the application you are suggesting, I assume you don't want that look. It sounds like letting it rust before the application would be the best bet.

Jun 25, 06 10:32 am  · 
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ichweiB

silverlake. I see you are in Los Angeles. I guess a bit far from Brooklyn. Sorry.

Jun 25, 06 10:33 am  · 
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e909

stronger after rust 'patina' forms? seems unlikely

Maybe you can workout a drain detail so that runoff is directed out of the way.
yeah. assuming the corten is otherwise a winner, a narrow buffer strip is the most obvious solution. but only if you can afford the space for a narrow strip of cover. put some vines on permanent trellises.

ironically, (i think) colored concrete is pricey.

Jul 4, 06 5:27 am  · 
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snooker

I think corten steel is alot mor pricey than colored concrete.

Jul 4, 06 8:47 am  · 
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Becker

the discolouration on the sidewalk is a beautiful thing. we have it on the sidewalk near where i work, and everybody loves it... then again we are all architects

Jul 5, 06 2:30 am  · 
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The Job Captain

we usually just use straight up unfinished steel, don't seal it, and let it rust. go into a junkyard and i'll bet you'll find 50 year old rusted cars that are still in tact. most people's perception of rust comes from their cars, and there's a whole other issue involved when you're talking about tons of road salt as opposed to just the natural elements.

Jul 5, 06 11:49 am  · 
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cynic

cor-ten never completely stops oxidizing...it just does so at a much slower rate than mild carbon steel. in fact, USS does NOT recommend using cor-ten architecturally anymore.

Jul 5, 06 2:57 pm  · 
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Jonathan Golli

Cort-ten reaches a "stable" oxidation point where further oxidation may occur, but never impeds the quality of the steel. Staining will occur on the concrete even if you pre-rust the cor-ten.

As for using unfinished steel...how long do you plan on having the facade last? Eventually the unfinished steel will corrode around the fasteners and possible fail in a strong wind load. But that could be 20 years down the road. Jonathan Seigel in San Diego uses cold-rolled steel on every project he does. It looks fantastic, but his buildings are only 5 years old at most. The salt water from the coast may speed the oxidation.

The best example of cor-ten on a building is the USS headquarters in Pittsburgh. One of my favorite skyscapers of all time. They built is in 1978 and stopped reccomending corten on building shortly after. Downtown tenants complained about the sidewalk staining, but I think its beautiful.

http://en.wikipedia.org/wiki/U.S._Steel_Tower

Jul 5, 06 3:53 pm  · 
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treekiller

The biggest constraint for using self-oxidizing steel in LA is it gets hot, it gets very hot in the sun. using it on the north facade is ok, but do you really want to create a furnace that will raise the ambient temperature any higher in our current heat wave?

Beyond any heat island effects- detail the connections/joints carefully - because you'll probably have greater then normal thermal expansion with cor-ten et al...

Jul 5, 06 6:33 pm  · 
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art tech geek

a thought on coating the core-ten or another steel. I talked to my stainless supplier about suitablility of ss in the southbay (los angeles). It gets eaten - its stainless - not stainfree, as he put it. There is an antigraffiti coating - a clear ceramic - don't know how it is applied - but he said that it would be the best coating that he has ever seen for controlling oxidation. It is also used on boat hulls. I'll try to find the name of it. It sounded like a great thing.

e-909
on the colored concrete - an ad mixture increases the cost of a pour 50% over plain grey portland. That is a ridiculous joke for a about $5-7 of colorant. courtesy of my tech rep buddy at LM Scofield - who also thought it was way out of line. But it could be a fine negotiating point with a contractor. If you know that - and they want the work - you could probably play a bit of hardball for a better job / look. A truck is a truck is a truck after all.

Jul 5, 06 8:05 pm  · 
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3tk

moneo used that ss panels in the auditori in barcelona, its oxidazing unevenly, and does seem to stain the sidewalk similar to corten.

as for the concrete, they have to adjust the mixing plant and clean it and the trucks afterwards, to accomodate regular grey mix. in our higher labor cost world that adds up.

Jul 6, 06 10:35 am  · 
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huwt

CF Murphy's Daley civic centre in Chicago is a thirty one storey tower with corten cladding. Where the expressed columns meet the granite pavement there is a beautiful sump detail to catch and control the rust - a simple set down in the granite of an inch deep. Looks terrific.

I have a corten question.

We are just documenting our first corten project here in Sydney, and planning to use 3M VHB tape as part of the fixing strategy. Bluescope steel and 3M are both happy about this on the basis that the panels are abrasively cleaned on the rear prior to the tape being applied (the tape is impervious to atmosphere and will limit the oxidisation of the material beneath) . The weight of the panels will be base supported, i.e. the tape provides lateral restraint only. Does anybody have any experience of using VHB tape with corten?

Jul 6, 06 11:17 am  · 
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silverlake

thanks for all the feedback....

i think i'm going to use raw steel with a clear coat so you won't have the rusted look.

then again, i might not use it at all - i have to go through a design review board with the city of glendale and await design feedback from their in-house architect. shudder...

Jul 6, 06 11:46 am  · 
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art tech geek

huwt - you might look at using a bostik aerospace adhesive. it is used to attach porcelain steel facade cladding. it might be a good alternate to investigate. I know that PG Bell Enameltec in Canada recommends it for their metal panels & have used it to adhere .25" to .625" #316L in Dallas on a project that could not be welded and was visible from every angle & side. They get wicked temperature variations of 100F occasionally (a great blue).

The coating mentioned previously is a Cerakote ceramic micro clear (company also makes powdercoating). It is recommended for among other things: marine environments, ferrous & non-ferrous, storefronts & anti-graffiti. It might work very well. Mfg is nicindustries

Have fun with Glendale........ arrrrrrgh

Jul 7, 06 9:02 am  · 
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treekiller

We have a freind in glendale: Alan Loomis who is now running their planning department. Drop him a note and see what his thoughts about the review board.

At least you don't have to deal with the CRA in LA....

Jul 9, 06 3:59 pm  · 
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snooker

oh....ya wicked temperatures....in working with steel always....I say always keep in mind the coeffiecient of thermal expansion. Steel grows like crazy. I can only imagine corten steel is worse because of the color causing a higher temperature. BE CAREFUL!!!!!!

Jul 9, 06 7:41 pm  · 
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anotherquestion

I wanted to revive this thread - any other recommends for sealing core-ten?
thanks...

Jul 26, 06 2:17 pm  · 
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urbanisto

Why sealing?
Isn't the sense of using Cor-Ten as jgolli has written, that it "reaches a "stable" oxidation point where further oxidation may occur, but never impeds the quality of the steel."

I have used it in a landscaping project: The Cor-Ten was exposed to the elemnts for 2 months before we actualy used it on site, nearly no stains on the Granite-paving in front now after about one year of exposure.
And if you don't seal it, it keeps the surface feel of rusty-steel, which I like, this might be lost by some sort of sealing.
(Of cours you can get stains if you start rubbing over it with your hand)

Jul 26, 06 3:26 pm  · 
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anotherquestion

because there is a lot of rain, and uneven exposure due to overhang/backsplash. they want to stop the patina process & control the progress.

i hear that there is a silica-based sealant or wax?

has anyone used/seen gavalume, core-ten's recommended alternative?

Jul 26, 06 3:36 pm  · 
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waxwings

no, but it must suck

Jul 26, 06 3:46 pm  · 
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threshold

Isn't galvalume (galvanized aluminum) silver? A very different look from core-ten?

Jul 26, 06 10:30 pm  · 
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vinnieb

The material has numerous benefits when compared with mild steel. It is a structural steel grade so has greater yield and tensile strength. There is only an issue with corten steel wearing through on thinner material. Corten is used often in bridge building projects so its wearing characteristics are not in question. The steel also requires little maintenance a it 'self protects'.

Certainly with such an attractive patina, its worthy of consideration for aesthetic purposes.

Jul 15, 10 11:17 am  · 
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mespellrong

there is sculptural supplier (in CA?) who sells spray applications for steel that match many kinds of metal finishes, including corten. I've used their Faux liver of sulphur bronze finish on outdoor sculptures and their gunmetal shellac on some service elements in kinetic sculptures, and have been satisfied with their performance.

Jul 15, 10 12:01 pm  · 
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snook_dude

Looking at moving the patina along....to get to the rich purple look of urban areas in a rural area....any thoughts? Looking for someone who has actually achieved this on a project.

Oct 26, 12 7:26 pm  · 
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snook_dude

I have worked with Bronze in Sculpture and with Patina to  achieve various  coloration but never with corten steel and wondering about the limitations.  Going to start doing some testing tomorrow to see what effect I can achieve.  If anyone has any experience with Corten steel and patina I would love to hear from you.

Oct 26, 12 8:52 pm  · 
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mdler

Persians dont like Corten...use gold

Oct 29, 12 1:07 am  · 
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snook_dude

Thanks mdler.....you still doing the food truck thing?

Oct 29, 12 6:15 am  · 
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snook do you mean rich purple, as in color of oxidization/patina?

Oct 29, 12 7:49 pm  · 
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andrewr

Hi  - what is the best way to remove rub marks on aged coreten steel....i.e. patina has been rubbed...so you see "cloudy" marks?

Sep 17, 16 11:41 pm  · 
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Non Sequitur
Sandblasting.
Sep 18, 16 12:02 am  · 
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andrewr

​what about something like oxalic acid to remove rub marks?....since Oxalic will remove rust....then can rust again?

Sep 18, 16 12:18 am  · 
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Non Sequitur
You can use plain old regular playdough. It'll polish that steel real good. Just make sure to specify that no red or orange type is used.
Sep 18, 16 8:49 am  · 
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andrewr

interesting...how would you apply it?....p.s. the steel is well rusted

Sep 18, 16 6:20 pm  · 
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ozziesculpt

I'm wanting to achieve coloured patinas on core ten to create a large outdoor sculpture that will sit on pavers. First of all, I'd like to know what solutions can be used on core ten to create greens and blacks, and even to stop it from rusting at all. The majority of the piece will be rusted naturally, but I want to create some variations. Any suggestions? Also, I'm reading above that sealants won't stop discolouration on the pavers, or that they will look "unnatural" - any other suggestions?

Sep 25, 16 1:49 am  · 
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canoli

Question: if you use the hydrogen peroxide / vinegar solution to accelerate the Patina on Corten Steel ... how many applications would you suggest?! How frequent? Does the solution compromise the steel in any way? Finally, will the Corten Steel still Patina the same over the long haul (2-3+ years) as if you did not use an accelerant?

Oct 28, 17 7:30 pm  · 
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ShakeyDeal

Anyone have experience with using COR-TEN AZP® prepainted steel as an alternative to Corten?


Feb 23, 21 2:28 pm  · 
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SneakyPete

I have not. corten is a bit of a misnomer these days. Being a genericized trademark, you might get tricked into thinking you're buying steel when you're not. That product looks a bit kludgy.

1  · 
ShakeyDeal

Agreed, definitely on the kludgy side. I've since come across a few pre-weathered options that look promising. Its for an exterior application - mostly concerned with staining of adjacent surfaces.

 · 

It's a PVDF coating on galvanized steel or aluminum. Not very convincing in my opinion, but it's warrantable and won't rust through (cor-ten steel can't boast that). I think there are better, more convincing options though. Pure+Freeform has some using FEVE coatings.

 · 

Take a look at Recla Metal, Bare Skin product.

1  · 

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