Flame painting

**ronnielyons** · 10-24-2007, 06:56 PM

Hello: I've been lurking on the list for some time and am posting in hopes of getting some instruction. I've searched the archives of other metal artist forums and haven't found quite what I'm looking for, so please forgive me if this has been repeated at some point in the past as I don't get to read everyday.

I've finally arrived at the point in my artistry that I'm no longer happy with just painting my plasma cut-outs flat black. I'm looking to step into the world of color and try some experimentation with flame painting. I'm working with .088 hot roll sheet and after cutting out I knock the mill scale off with a flap disc down to bare, shiny steel. Using my brazing tip and working very slowly and patiently I can start to see the bare metal darken into maybe a light brown, and then blue then the blue will turn sort-of a grey-silver color if I overheat it. Buff it back out and go again, so far so good.

My question is how do I produce the variety of colors I've seen on projects on the list. Golds, yellows, coppers, deep-rich blues and reds. I know some folks use copper sheet and some use stainless, but I'm using mild hot roll carbon steel at this point. Seems I remember seeing something about painting the metal with a borax solution before heating...? Is there a trick to treating the metal that helps bring out the variety of colors? I would truly appreciate any feedback you can give me...I'm really excited to learn this technique. Thank you !!!

Ronnie Lyons
Meridian, ID
cog4150@hotmail.com

**Broccoli1** · 10-24-2007, 09:25 PM

Ronnie,

The only thing I can think of that the Borax is doing is oxidizing the metal quickly and that is where you will possibly get some reds/rust colors.

With mild steel there ain't much you'll get with the colors, other than what you have seen, by just using the Flame. You can try buffing the steel to a really bright finish and that will affect the color changes but not much. You can try a Mapp or Propane hand held torch also.

There are patina solutions that are applied Hot or Cold to achieve various colors.

**txfireguy2003** · 10-24-2007, 09:29 PM

I don't really know where it comes from, but I have seen all those rainbow colors after grinding too long in one spot. If you overheat the metal with the grinder you can get the different colors, so I would think your could get the same with the flame. I don't know, but sounds like maybe you're getting there and going past it too fast to see it. I've only used mild steel as well and I've gotten all sorts of colors with the grinder.

**Broccoli1** · 10-24-2007, 09:31 PM

Yup, it definitely happens fast

**preacher2** · 10-25-2007, 09:24 AM

I have been experimenting this for a while now but I sill have a lot to learn.

Yes it does happen fast. You can over heat the steel is less than one second, however when you take the heat away the colors may still be changing for several seconds.

I have found that an oxidizing flame seems the bring out brighter colors. If possible I like to heat the back of the steel. This way I feel I have a little more margin for error and it still gives me good color.

When I am looking for uniform color I put the steel in my kitchen oven. I set the temp to 500F and check it often. It only takes 5 to 15 minutes to get good color in sheet metal and but may take one to two hours to color heavier stock.

It seems that there are a large number of factors that effect the out come of this process, temperture, alloy, surface contamination, amount of oxygen in contact with the surface, contamination in the flame ect.

But here is a table to get you in the ball park, this is for plain carbon steel all temperatures are in Fahrenheit.

430 very pale yellow
440 light yellow
450 pale straw-yellow
460 straw-yellow
470 deep straw-yellow
480 dark yellow
490 yellow-brown
500 brown-yellow
510 spotted red-brown
520 brown-purple
530 light purple
540 full purple
550 dark purple
560 full blue
570 dark blue
640 light blue

This table came form Machinery's Hand Book twenty-first edition.

Good Luck

Preacher

**ronnielyons** · 10-25-2007, 09:39 AM

Thanks guys. Preacher, what is an "oxydizing" flame...is this a flame produced by more acetlyne than oxygen, in other words not properly mixed?

**usmcpop** · 10-25-2007, 10:23 AM

The color is caused by a very thin oxide layer that forms when the steel is heated. (edit: the color is due light interference effects, not the inherent color of the steel or the oxides.) It is a function of both temperature and the time held at the temperature. A long exposure at a lower temperature can result in the same color as a short exposure at a higher temperature.

Here's a nice color chart: http://www.anvilfire.com/FAQs/temper_colors.htm

An oxidizing flame is one that has an excess of oxygen, not one that just has sufficient oxygen for the fuel gas used (a "neutral" flame).