heat treating metal - lots of questions

[parrotlady]

Hi all, I hope no one minds me posting this in this area

I am trying to find out more info on heat treating metal.. I have experimented a bit, but before I waste too much more material, I thought I should ask a few questions..

First off - What kind of metal works best? Cold rolled, hot rolled, SS, copper? What happens if you heat something galvanized like Satin Coat (besides damaging your health?)

Secondly - pretending you were working in room temperature on say 20g cold rolled steel.. APPROXIMATELY, how long would it take to get a nice blue on one small spot? I am just looking for a ballpark here..

Can you go too far with heat treating? For example, will it turn red hot and then nothing?

If you do go too far, can you cool it down and do it again, or is it "a one shot deal"?

Must it be polished or sandblasted first?

Do you have to use acetylene, or will a regular propane torch work?

I think thats all I can think of for now.. Any suggestions/literature/pointers would be immensely appreciated!

Thanks so much!

[jim]

Hey Parrotlady
I do a lot of heat treating on metal. Cold rolled works the best .You wont get a good bluing on hot rolled because of the boiler slag on the metal. I find what works for me is to lay the metal out on a flat surface i have a gravel area it lets a little air under the metal. If you do it on concrete the concrete will start poping. I grind the metal first with a 60 grit flap disc. I use propane with a large RED DRAGON propane torch kit. When you start add a little heat at a time till you get used to it you will first get blueing Then the longer you keep the heat on it will start to go more brown . It takes a lot of practice to get the look you want but if you go to far just grind it again with the flap disc. Once you get on to it you will be amazed at the effects it will give you.
Hope this helps a bit Jim(murals in metal)

[JJ13]

Add my .02 here. The polishing is very important. The finer a polish you put on the metal the more vibrant the color becomes (to a point). Also, stay away from the galvanized. It is a pain to sand or blast off the zinc coating, and it won't color. The color you see on the metal is oxidation (basically rust), it is only a thin layer on the steel, so it is very easy to sand off and start over again. Most of the colors you are after (purple and blues) can be attained around 600-700 degrees. My favorite torch to use is called a henrob, or cobra torch. It uses oxygen and acetylene, but small propane torches work fine too. It takes a lot of practice to get good at heat coloring (I am stubborn, i'll get their some day)... be patient!

[04 Marine]

I found this website while surfing the net one night and it has a lot of good information on heat and chemical coloring of metal. http://www.johnsearles.com/metal-tips-techniques.html Hope this is a help.

[parrotlady]

Thanks everyone for your help! I have had some success after your suggestions.. I found that after I grinded the metal, I placed the piece on top of my wood stove (above it on a grate) and then torched it. Seemed to save some time and propane by preheating it.

Thanks again,
You guys are awesome!

[Metal Troll]

Thanks for all the info on heat treating until i read this post i had never tried it and have to say I am having some awesome results and as soon as I can i will post some pictures of the items I have treated.

I have a slight problem in the fact that the metal that i am using is hot rolled because I have a large supply of 14ga and 8ga to play with from a job that we lost when the company we were suppling closed up. So needless to say I have a couple tons of metal sitting in my storage shed getting rusty.

I have been doing small stuff and using my 4 1/2" grinder with a stone to knock off the surface to expose the nice shiny metal and then using my 40 then 60 to 80 grit flap wheels to take out the lines and but a finish onto my parts which when treated looks amazing but it is very time consuming with a grinder. I have tried using the 40grit first to try and speed this up but it doest seem to want to cut the surface of the metal to expose the shiny good stuff. I dont have access to a sandblaster and i want to try a large project but I dont want to die of old age grinding on it if I dont have too.

Any suggestions or tips to speed this up?

Also here are a couple of files that i did that looked very cool when done. The angel fish look sweet all treated but the sun is 36" x 36" and the idea of grinding it is daunting.

SUN.DXF

SMALL ANGELFISH.DXF

ANGELFISH.DXF

[peepers]

I have found that sand blasted steel does not produce the same desired effect when heat coloring. The more mirror like the surface is the better. I too use the flap sander disk on a 4 1/2" grinder. Some time I use more grit to leave some texture in the steel. I find that the texture gives a nice effect when viewed at different angles.

[JJ13]

I would suggest getting some 36 grit sanding discs on a 7" grinder ( the kind you use a plastic backer behind). Sand the piece evenly. Then switch to a 60 grit disc. Then 80, then 150. After the 150 switch to a DA with 50 grit sandpaper. After sanding with the Da ( I use a porter cable electric da from lowes) you can polish your pattern and color away. I can do a 36" square piece in about 20 minutes.

[AIRFLOWKID]

JJ13,
O.K. You got me on the DA . What is a DA? I'm probably going to feel stupid when I find out!
Thanks Tim

[Loyd]

A DA is a type of pneumatic sander that has multiple sanding actions used for body work.
Loyd

[Loyd]

Hey metal t, Thanks for the files. There is a machine called a timesaver that would take care of your issues with metal finishing. You may find one
at a place that buys and sells used machinery. They work great. BTW, I used to live in mesa and across the river in blythe, CA.
Loyd

[JJ13]

A DA is a Dual Action sander. It makes sure you don't leave any concentric scratches in the part. It is the very last thing I do before I polish any part. I prefer the electric ones. IIRC mine was $59.00 at lowes.

http://www.lowes.com/pd_241413-70-343K_ ... Ntt=sander

[Metal Troll]

Thanks everyone for the info this gives me a few things to try and I have a couple that I came up with on my own and if they work i will let you know.

[AIRFLOWKID]

Plasma Dudes,
Thanks for the info. on the sander ,just didn't know it by that name.
Thanks Again, Tim

[Wine Country]

A DA is a type of pneumatic sander that has multiple sanding actions used for body work.
Loyd

Hello Loyd,
The term DA means "dual action". I have a National Detroit pneumatic DA sander and the Porter Cable electric sander mentioned before. I like the electric for metalwork as I do not have to listen to my compressor run too. It does a nice job on cold rolled steel and gives a finish that looks nice just clear coated. Marty

[AnotherDano]

Wine Country - and anyone else...

What grades of paper are you using for finishes?

For a torch finish (for instance) how heavy do you start and wind up - and the intermediate steps - for a 'polished' finish?

I am using 60 to grind off what little dross I have on aluminum and to give the material some good tooth for a powder coat. Working well for me.

[Loyd]

Thanks Marty. I knew what it was, didn't know how to put it.
Loyd