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Preserving rust finish on outside mild steel.


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I have an outside gate project that is going to consist of 3" x 3"x.25" mild angle frames back to back  and galvanized stock panel in the middle.

Looking to get a Cor Ten looking finish with out using Corten.  What is everyones experience with sealing or clear coating rusted steel.



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Corten look without using Corten means you either have a top notch faux rust paint job or you have rust.  And if you mix Corten with other alloys and metals you will have faster rust.  Use Corten by itself, including fasteners and welding rods.  


Once you have rust on A36 it will NEVER stop growing.  You can only slow it down.  Stainless steels and Corten will get you decades or more.  Bronzes are even better.   Galvanized and professionally painted steel hits a good point on the cost/quality curve.  


Rusty mild steels will continue to rust, especially in the humid Southeast USA.  For exterior application oils, waxes, clear coats will buy you perhaps 5 unmaintained years, perhaps a little more if you do a crazy good job with both joint design and finishing.  And don't just think about how your work will look in 10 years, but will it be dripping rusty water onto a concrete drive or pedestrian walk and causing staining?  


Bottom line, if a client can't afford stainless or other high end material, get them to pay for a high end galvi/faux rust paint job.  If they don't want to pay for THAT (cheaper than SST, bronze or Corten) then get them to sign something saying you will not be responsible for degradation of the product.  Some education of the client/architect is required.  


This is where some people will jump on me and claim that something they made 10 years ago with an oil finish is still just fine.  And that may be true in Arizona or some similar place, but in 100 years?  Or on a sea coast in 5 years?  The enduring quality of your work is your best reputation maker/breaker.  Don't know about you but I plan to still be in business 20 years from now.  

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Greetings Trin,


My experience with rusted metal is that if you apply any hard coat paint or clear it will chip and flake...  I think if that's the surface color and texture that you are shooting for I would use an oil finish or soft wax...  I have used a special furniture oil in the past with some success but it is no longer available.. You might try a comparable tung oil ...  Keep in mind this must be maintained..   A soft wax would work but in the summer heat it would require more applications.   Good luck


Forge on and make beautiful things


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For outside, if you paint, you must put down first a good primer.  This must be preceded by cleaning the entire piece with a rust stopper, cleaner and degreaser, and not touch by human hands after cleaning. Then painted.  So, painting is really not a one step process.  Good luck. 

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