Cor Ten clad house

[Judson Yaggy]

Some folks in another thread asked for pics of this. Private residence, exterior is 90% done, materials are antique barn board, Cor Ten steel, and western red cedar. Cor Ten is 16 gauge, sandblasted and patina accelerated with a sprayed on mix of water and bleach. Fastened with a mixture of 3M 5200, hidden screws and big decorative pan head screws in the field on larger pieces. Steel gave radically different appearance depending on the weather and temperature when treated.

This week's project has been one of the exterior stairs, mahogany treads, 3/16" stainless risers, and structural steel supports. Very picky work, less than 1/32" tolerance anywhere because of the way one piece integrates with other elements.

Photos are just snapped off the phone, so not top notch.

[IronAlchemy]

Judson - I love the look of the stairs with the stainless and mahogany together. I am doing a personal house addition at the moment that will use Corten panels. Seemed appropriate for a house for a blacksmith. :-) I have a few test panels out weathering now but did not use any surface treatment for the initial tests. From looking at a number of other houses in North Carolina that used Corten, they seem to eventually weather evenly over a period of years. However, it would be nice to have things looking a bit more final more quickly.

Any advice as to what the variables were that affected the finish? Was it primarily the temperature and humidity? Also, what grit did you use for the sand blasting. I assume you did that before installing the panels?

Did you try any with muriatic acid (HCl) and peroxide? That is way more aggressive than bleach and gives immediate surface oxidation. It might be more controllable. I have not yet done HCl/peroxide tests on my panels but it is on the list to do this fall. The deeper almost purplish color of older Corten seems to only come with many years of oxidation.

From the many examples of Corten that I have seen, I think that that there is a risk that the lower parts of the exterior wall will show rust stains if any water runs off the Corten from rain or condensation. It looks as if there is considerable protection from the overhand so maybe the problem is mitigated. The stains show less on a darker wood exterior as well. The stainless would be toast though.

Hope all goes well with finishing the job.

Thanks for sharing.
- Doug Wilson

[Dillon Sculpture]

Very cool Judson, you guys do top notch work for sure. Love the extreme overhang in the first shot, looks like its going to take off! Thanks for sharing, hope to see some of the homes interior as well. I have used spa oxidizer on steel with great results in the past.

[Bob S]

very nice. thanks for the pictures and description.

[Judson Yaggy]

Thanks everyone.

Sandblasting media was whatever our usual guy uses as his default, Black Beauty or similar. Not sure of the exact size. Weather conditions were definitely a factor, some pieces were rusted in sunny 50 deg., some windy and 20, some while raining, some while snowing. Even several rounds of freezing rain. Welcome to Vermont! Drying time seems to be one of the biggest factors, the faster the mix evaporates the lighter, more orange the rust will be. Second most important seems to be temperature, lowest temps produced the least rust.

I considered and rejected using more aggressive oxidizers, decided against using them because of the sheer volume of overspray I would be standing in and blowing around the job.

Doug, pm on the way.