grobinson2 wrote:I know this is an old thread but I am looking for the proper paint to paint my "new to me" cast iron radiators with? I found a local guy that sand blasts them for $10.00 each. I plan on painting one with Rutland black stove paint. That said I have another large one that I would like to match my latex red wall. Can oil based paint work on radiators or will it just crack off? A friend of mine suggested auto motive paint.
Cast iron "Radiators" actually use convection as there primary heat transfer medium. Surface texture/finish will have little effect on the radiation as long as the paint isn't so thick that it insulates the metal.
What are you planning to run your system at? If it is a steam system you may need a paint that can handle up to around 220-230 deg F. If you are running hot water, then 180 is the norm. Rarely should you need more than 180 deg. water to CI radiators.
Go to a paint store like Sherwin Williams and ask what they would recommend. The people at the big box stores are not versed in special applications. Spend a few extra bucks on a gallon of quality paint.
Sometimes latex paint can be more flexible that oil based paints. This is important on a radiator that constantly expands and contracts from heating and cooling.