Welcome to ArtMetal, Jason!

The simplest brown patina for steel is basically rust. For centuries steel was allowed to rust, then lightly scuffed to remove the loose rust and allowed to rust some more. The process was repeated a number of times until a very fine, even layer of oxide was on the surface and that was then oiled to preserve it. The rust molecules being much larger than the iron molecules enable them to hold the oil and protect the surface from further oxidation. Look up "browning" in Google and you'll see a number of sources for chemicals to speed up the process. They're available from Birchwood Casey, Hoppe's, Herter's and others.

You have good reason to be concerned about the heat affecting a surface finish on a fireplace screen. Paints and clear coats aren't going to survive long. The best be I know of is to use a browning agent and then wipe the item down with a high-temp silicone oil. Provide some oil for the client to use periodically and it should hold up pretty well.

There are some high temp paints made that are advertised to withstand temperatures up to 1200F for brief periods and 1000F for sustained periods, but the colors are limited and I don't know if they can be intermixed. I have a new forge I painted with such paint from Dampney Company, called Thurmalox, and it has held up for the first couple of firings, at least. I'll tell you more in a year or so about long-term durability.

Rich

In my experience high temperature paints and even many ordinary industrial matt paints hold up pretty well for firescreens and canopies/hoods but I'm talking freestanding sparkguard type screens that stand off from the fire a little....I know in the states you often have hook on or hinged screens that butt right up to the fire, which is a big ask for any coating to withstand longterm.

Another popular and traditional finish for stoves, ranges and other fireplace accoutrements over here is graphite based polishes like "zebrite" and "zebo" available in any colour 'long as its black. (or there is a hard to find silver version called "zebracier") Filthy stuff but o.k. in the days when the maid dealt with all that stuff!

As usual can't disagree with Rich....for a brown finish a bit of controlled rusting,stabilised and maintained with an oil or wax coating's a pretty good bet. Might burn off but won't be as yucky as a solvent based lacquer burning off!

Will Jones

Ivan Bailey
I've made a lot of fire screens and a lot depends on which part of the country you live in. Down in the south here, one can get away with using bronze screen wire ( Hanover Wire Cloth) It is very fine, and of course is closest to the fire, it tends to dissipate heat and especially when the screen is freestanding and is a couple of inches in front of the face of the fireplace the steel doesn't get too hot to use oil base paint. The other alternative is stainless steel cloth, (Mc Nichols Supply) Its a lot heavier and is a good heat shield , but adds a lot of weight. Also very expensive. I've recently use Rustoleum spray stove paint. Its a sort of flat black and scratches off fairly easily, but does reveal the detail of metal forming because its a sort of grayish black. I imagine there would not be significant volatiles coming off it because of the high heat associated with wood stoves.