painting radiators

[drewmo]

Next project includes redecorating some of the rooms in the hotel. New paint for every surface, including the radiators. I have oil-based paints for the trim and was hoping to use that. I know if I ask the paint store, they'll try to sell me a metal-specific paint. Is it necessary? I want to do the job right, but I don't want to end up with more half-used cans of paint than necessary. Also, is it better to paint the radiator when it's cold, or is it ok to paint warm?

 

[Corey]

With any painting project, surface prep is the key. Regardless of the paint you use, make sure the surface is free of any loose paint, oil, grease, wax, dust, etc. You don't necessarily have to remove all the old paint as long as it's still tightly stuck to the radiator - and you're willing to live with any minor surface imprefections which are already in the old paint. Once you scrape/wire brush any loose paint and use a degreaser to clean the surface, it would probably be good to rough up the remaining surface with a bit of medium grit sand paper. This way, the new paint will have the best possible chance to stick. Also take care if you think the old paint might contain lead. In the states, anything prior to ~1973 has the possibility of lead...don't know about the other side of the pond.

The oil paint should be fine, I've seen plenty of latex over metal as well - with decent results. Be prepared for a little bit of smell the first time the radiators are heated (ie - any chance of delaying the painting until late spring when you could fire up the radiators and crack a window to vent the fumes?) Last, I would paint the radiators when they are close to room temp (ie 20-25C for you metric system types) - there should be a temp range on the can, but usually too cool and the paint won't dry very fast which means it can pick up a lot of dust and possibly sag or run on vertical surfaces. Too hot and it will dry before it's had time to 'self level' which means a lot of brush strokes will be visible. You could also have trouble with 'solvent popping' where the surface of the paint begins to dry but the heat causes the solvent to boil out and make tiny pinhole bubbles in the surface.

 

[drewmo]

Thanks for the detailed response, Corey. Good to know both oil and latex paint can work. The radiator is clean and the old paint doesn't show any sign of deterioration, other than it looking a bit old. I'll take your advice and sand it the best I can then clean it with a bit of white spirit. Shouldn't have to do any scraping as far as I can tell. I'll have it shut off, but it should still have a relatively warm room temp considering the size of the building and this is just one room. The paint gives no min-max temps for when to paint, although it says at 20C and 65 percent humidity, it'll dry in 8 hours. Once the paint is dry, I can shut the door and open a window to burn off any odors.

As for the color, CC, the ladies of the house have the final say. And black is not it. Any idea how a dull yellow radiates?

 

[Gooserider]

In theory black will radiate best, white worst with a range in between. In practice, I don't think you'll see an appreciable difference - the theory is true, but there are other factors that matter far more than the color.

Gooserider