exterior metal door
#7
  
Been asked about a door.  Appears that the factory primer is coming loose in sheets. Looks to have never been painted. Needs redone. 

My thoughts are to strip it (probably scrape and sand) and then prime and paint. Unsure on what primer to use. Thoughts and suggestions?
It's all good till it's no good anymore.
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#8
  Re: exterior metal door by rh111 (Been asked about a d...)
Can you spray it?

I'd look into an epoxy automotive primer and finish.
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Wild Turkey
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(joined 10/1999)
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#9
  Re: RE: exterior metal door by Wild Turkey (Can you spray it? ...)
(03-04-2019, 01:08 AM)Wild Turkey Wrote: Can you spray it?

I'd look into an epoxy automotive primer and finish.

If you don't have spray equipment, look for an acid-etch primer. Strip and clean the door. If you use any solvents while cleaning, wash with dish soap or yellow ammonia (1part yellow ammonia, 10 parts water) and water afterward and then rinse with clean water. Remove as much rust as possible. Treat the remaining rust with a Rust Converter and prime over it and paint. You might find brush-able products cheaper than the aerosol products I listed below.

Acid 8 primer

Rust Converter
 
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#10
  Re: exterior metal door by rh111 (Been asked about a d...)
Rustoleum gained its fame for paints for steel, and especially primers for steel.  

I think the primer is the key.

I would suggest a finish with a high zinc content.  The zinc acts as a sacrificial anode to protect the steel (remember the Periodic table?).

https://galvanizeit.org/corrosion/corros...ial-anodes

This product:

https://www.rustoleum.com/product-catalo...nc-primers
No animals were injured or killed in the production of this post.
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#11
  Re: exterior metal door by rh111 (Been asked about a d...)
Steel needs a different primer than aluminum. I found that out when I painted some of my siding. It is steel lap siding with insulation glued to the back side. The factory finish finally gave up the ghost on the south sides(garden shed and garage) where evergreen hedges brushed the surfaces for several years. The other gotcha was the white paint necessary. Meaning an red oxide primer was not the best choice. Sherwin Williams sold me a white steel primer(tintable) which I sprayed on with a Wagner Flexio HVLP sprayer---was sprayable without thinning. I did spray and back roll, however.




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#12
  Re: exterior metal door by rh111 (Been asked about a d...)
Steel bridges face the same elements.  Here is how they battle rust:

https://www.highsteel.com/technical-reso.../coatings/

or Bridges:

Repainting a bridge, or even performing paint repairs on a bridge, can involve expensive traffic control and rigging.  That is why the right coating system is critical to bridge owners.  Prior to the 1970’s, bridges were painted with lead based primers instead of today’s zinc rich coatings that provide galvanic protection.  Prior to the 1970’s, bridge steel was not routinely blasted to remove mill slag either.  Those old systems had shorter life cycles requiring expensive repainting efforts.  Today’s most popular paint systems use zinc primers with additional coatings of epoxy and urethane paints.  The zinc will protect the steel from corrosion, while the top coats protect the prime coat and provide the color and sheen desired.
No animals were injured or killed in the production of this post.
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