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How do I paint cast iron steam radiators?

Help, My father (owner of a plumbing & heating store for over 30 years) passed away 4 years ago and with him went all my knowledge for steam heat!

I have a home built in 1910, it is heated with steam heat. We have decorative radiators that need to be repainted, as the paint is peeling.

Can someone please share their knowledge in how to paint these radiatiors with me?

thanks so much!


  • John Felciano
    John Felciano Member Posts: 411
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    the "Hot tech topics" in the menu to the left.Lots of great info there....

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  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Since paint is peeling...

    ...first you MUST strip. I know of three workable methods--none easy and all messy. In all cases plug all holes in the rad.

    1) Take to a monument (tombstone) works for sandblasting. They generally have the largest, fastest equipment. Exceptional job (it will look like raw cast iron) but can be expensive and inconvenient to haul long distances.

    2) Pressure wash with a zero-degree (rotating) head. This is a bit tedius and messy and of course must be done out-of-doors. May not remove every last bit of the old paint, but what is left will be very well-adhered and not troublesome for most finishes.

    3) Build plastic lined wooded troughs about 1/2 the size of the radiator and soak in a strong lye solution. (sometimes over and over to multiple coats). Really nasty, but quite effective.

    People have tried other methods of stripping rads but invariably vow "never again" if they even manage to finish a single one.


    Latest is powder coating. Rad must be sandblasted first and this may not available in all areas. Can get really expensive for large rads. Extremely durable, even finish.

    If not powder coated, you need to prime with OIL paint ONLY. If used on a steam system, you should find paint rated for at least 230 degrees--you might have to go to an automotive store to find it. Most common oil paints are OK with hot water rads. A flat finish is always best for priming.

    For finish coats:

    Most traditional is bronzing. I venture to say that most residential rads were originally bronzed except those in high Victorian homes where ornamental rads were actually painted in contrasting colors--dramatic but gawdy. Powders and oils are available in big cities and at www.sinopiaonline.com (look under Powdered Mica and Pigments).

    If using plain paint, oil base really is preferable. The water in latex paints can quickly rust the underlying iron and ruin the finish in short order. Again, watch temperature ratings for steam rads.

    If you want more details, e-mail me.

  • John@Reliable
    John@Reliable Member Posts: 379
    Rad Paint

    Any color you want but silver,I tell customers to match the wall color.Clean and prime spots, paint with oil based paint and heat (bake slowly) use brush and "hotdog" roller for inside parts and alot of time,no eazy way.This will work for most and cost is low. Sandblasting works good also but is high end on cost. Hope this helps
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