Heating Confusions

[Alex Melton]

Hello, I've heard people describe steel as "white hot" before, but I have never been able to get my steel that hot. Is it referred to as "White" hot because that's the color it is on camera? While doing some forging practice this morning, I took out my phone camera and the steel appeared white on the screen even though it was only a bright orange to my eyes. Can y'all help clear up my confusion?

[Geoff Keyes]

White hot is indeed a visual color.  For most of what we (the smiths here) are doing. white hot is way too hot.  At that point you are burning carbon out of the steel, and you need carbon for the the steel to be steel, and to harden.  The color the camera sees is not a goo gauge, the light from a forge overwhelms the camera pretty fast.

Color is important, but is not an absolute measure of temperature.  In bright sunlight, steel at 1800 F is grey.  In dim light, 1500 F can appear much hotter than it is.  It's why smiths without any way to gauge temperature other than their eyes, will often HT in very low light.

 

Geoff 

[Alan Longmire]

To add to that, it can be difficult to get steel white hot in a venturi burner propane forge if both forge and burner are not well designed and tuned.  In my coal forge I have no difficulty getting steel white hot, with sometimes unfortunate results...

[Austin_Lyles]

Never use a camera to gauge your heat. Exposure is all over the place and every camera or video will show a different color. White hot is something you never want. It indeed looks, to your eye, white once you get it there, usually accompanied by sparks. It's something we avoid as smiths, and lemon yellow (or thecolor of your forge) is what we look for in steel for forge welding, but we never go past that....on purpose anyways. 

[Alex Melton]

Okay, Thanks guys. This really clears up my confusion.