Temperature colours

Temperature colours

This topic has 6 replies, 5 voices, and was last updated 30 July 2014 at 16:50 by Neil Wyatt.

Viewing 7 posts - 1 through 7 (of 7 total)

Author

Posts
26 July 2014 at 09:08 #23425
Bill Dawes
Participant
@billdawes
Advert

26 July 2014 at 09:08 #158773
Bill Dawes
Participant
@billdawes
Hi all, does anyone know if the type of metal affects temperature colours.

In my 50 pus years in engineering I cannot recall researching this, maybe because I have not generally been much involved in the non ferrous side.

Asking the question because my 'googles' for temperature charts don't seem to differentiate.

Bill D.
26 July 2014 at 09:20 #158776
Michael Gilligan
Participant
@michaelgilligan61133
Bill,

The emitted colour when hot [as opposed to any cold coloration] is "black body radiation" and a such will, to all practical "engineering" purposes, be the same for every material.

MichaelG.
26 July 2014 at 09:21 #158777
Les Jones 1
Participant
@lesjones1
Hi Bill,
If you are talking about the colours for tempering (Eg straw, blue etc.) I think it depends very much on the metal as the colours are due to the oxide formed on the surface. If you are talking about red heat then I would think it would not depend on the metal as the colour is a function of the wavelength of the radiation at a particular temperature. This is just my feeling on the subject. I have not verified that my understanding is correct.

Les.
28 July 2014 at 00:02 #158905
Bill Dawes
Participant
@billdawes
Thank's guys, that is the conclusion I came to having looked at various sources, but without finding anything definitive or conclusive.

Take your point about tempering colours though Les.

My question came about by recent annealing of copper by heating to red heat, it set off a train of thought as sometimes happens.

Bill D.
30 July 2014 at 16:01 #159136
Jon
Participant
@jon
Bill with steels I haven't in 23 years noticed any difference be it weldable quality ms of varying specs, 01, silver steel, CR4, EN8, 9, 32, Vanadis, various spring steels new and old, cfs or dom to name a few. Normally 230 degrees to 280/285.

Stainless steels G303, 304, 316S11 do require a lot more heat to cherry red to achieve similar colouration when cooled. Bit hit and miss.
30 July 2014 at 16:50 #159141
Neil Wyatt
Moderator
@neilwyatt
The colour is caused by light interference effects that depend on the thickness of the very thin oxide film (same effect as a soap bubble or some beetle's shells). This just involves the iron and oxygen so is pretty much constant for all steels, but it gets thicker with time as well.

This is also why you don't get a proper colour inside the flame, as there isn't normally enough oxygen for the film to form properly

Neil
Author

Posts

Viewing 7 posts - 1 through 7 (of 7 total)

Please log in to reply to this topic. Registering is free and easy using the links on the menu at the top of this page.

Code of Conduct

Latest Replies

Viewing 25 topics - 1 through 25 (of 25 total)

- Topic
- Voices
- Posts
- Last Post
- My Intro
  Started by: Martin Freestone in: Introduce Yourself – New members start here!
- 1
- 1
- 15 July 2026 at 13:27
  Martin Freestone
- Help please! Workshop clearance
  Started by: ksw in: General Questions
- 9
- 19
- 15 July 2026 at 12:57
  ron vale 3
- Pipe Size Puzzle.
  Started by: Nigel Graham 2 in: Locomotives
- 5
- 10
- 15 July 2026 at 12:41
  Charles Lamont
- Plug in Solar 1 2 3
  Started by: Vic in: The Tea Room
- 25
- 75
- 15 July 2026 at 12:34
  Robert Atkinson 2
- Solar Panels 1 2
  Started by: Vic in: The Tea Room
- 16
- 43
- 15 July 2026 at 12:29
  Tony Pratt 1
- Maisie
  Started by: ian Holdsworth in: Beginners questions
- 5
- 6
- 15 July 2026 at 11:44
  JasonB
- Band saw 1 2 3 4
  Started by: Peter Simpson 3 in: Beginners questions
- 24
- 76
- 15 July 2026 at 10:59
  Adam Harris
- What Did You Do Today 2026 1 2 … 5 6
  Started by: JasonB in: The Tea Room
- 41
- 140
- 15 July 2026 at 10:31
  jaCK Hobson
- Bending copper tube?
  Started by: Bo’sun in: Workshop Techniques
- 16
- 20
- 15 July 2026 at 10:30
  bernard towers
- QCTP 1 2
  Started by: James A in: Workshop Tools and Tooling
- 19
- 32
- 15 July 2026 at 09:16
  JasonB
- Myford VMC Spindle Advice Please. 1 2
  Started by: Nigel Graham 2 in: Manual machine tools
- 12
- 49
- 14 July 2026 at 20:02
  Graham Meek
- What is this? 1 2
  Started by: Sonic Escape in: General Questions
- 18
- 26
- 14 July 2026 at 19:52
  Andy Stopford
- Offen imperial bore mic gauge.
  Started by: Graeme Seed in: Workshop Tools and Tooling
- 6
- 13
- 14 July 2026 at 19:30
  Graeme Seed
- THE MONTHLY TIPS COMPETITION – THE ENTRY THREAD! 1 2
  Started by: Neil Wyatt in: Hints And Tips for model engineers
- 19
- 46
- 14 July 2026 at 17:40
  Neil A
- Smart & Brown model A spindle lock
  Started by: old mart in: Workshop Tools and Tooling
- 2
- 9
- 14 July 2026 at 14:53
  old mart
- Bonding brass hubs to steel
  Started by: mikemunson in: Beginners questions
- 3
- 4
- 14 July 2026 at 11:27
  Michael Gilligan
- Lathe coolant applicators 1 2
  Started by: lucerne in: Manual machine tools
- 16
- 30
- 14 July 2026 at 09:15
  Julie Ann
- Bridgeport Series 1 CNC 1 2 3
  Started by: tomcnc in: CNC machines, Home builds, Conversions, ELS, automation, software, etc tools
- 12
- 58
- 14 July 2026 at 01:49
  seemack
- Small electromagnetic pump via E-Bay
  Started by: Clive Foster in: Manual machine tools
- 5
- 8
- 13 July 2026 at 20:02
  John Hinkley
- Windows 11 background pictures
  Started by: old mart in: The Tea Room
- 4
- 4
- 13 July 2026 at 19:49
  Mark Rand
- pitman arm
  Started by: martin haysom in: General Questions
- 6
- 9
- 13 July 2026 at 17:00
  Dave Halford
- Martin Cleeve Swing Clear Retracting Toolholder 1 2
  Started by: Roger Harvey in: Workshop Tools and Tooling
- 18
- 27
- 13 July 2026 at 15:21
  ega
- Boiler problem
  Started by: Zan in: Help and Assistance! (Offered or Wanted)
- 5
- 8
- 13 July 2026 at 14:25
  Zan
- First Printer
  Started by: vintagengineer in: 3D Printers and 3D Printing
- 7
- 8
- 13 July 2026 at 13:47
  John Haine
- Mini-lathe parts source
  Started by: Dunc in: General Questions
- 7
- 12
- 13 July 2026 at 08:28
  Dell

Viewing 25 topics - 1 through 25 (of 25 total)

View full reply list.

Latest Issue

July 2026

Buy Latest/Back Issues

Newsletter Sign-up

Latest Replies