Straw parts

[Norme]

To appreciate the range of colors produced by heat treatment one need look no further than the hold-opens on Imperial era Lugers, some of which display a spectrum of colors (see photo).
Krieghoff Lugers are frequently encountered with a mixture of yellow, orange and vivid blue small parts, likely a result of erratic temperature control.
Norm

[DonVoigt]

Originally Posted by Norme

To appreciate the range of colors produced by heat treatment one need look no further than the hold-opens on Imperial era Lugers, some of which display a spectrum of colors (see photo).
Krieghoff Lugers are frequently encountered with a mixture of yellow, orange and vivid blue small parts, likely a result of erratic temperature control.
Norm

Norm,
that is a great picture, it shows on the one piece the range of temperatures reached on the hold open, from the bright polish to light yellow, straw, brown, red, purple, bright blue, peacock blue, and then into grey.

Many have seen the attachment below often posted before showing the colors and corresponding temperatures.

Kyrie,
Thanks for your post, I do hope it puts a stake through the heart of the misconception about "staw" and corrosion.

[Kyrie]

Originally Posted by Norme

To appreciate the range of colors produced by heat treatment one need look no further than the hold-opens on Imperial era Lugers, some of which display a spectrum of colors (see photo).
Krieghoff Lugers are frequently encountered with a mixture of yellow, orange and vivid blue small parts, likely a result of erratic temperature control.
Norm

Or could be a good example of selective heat treatment. Plant the rear of the part in a heat sink, flame harden and draw the front of the part, and the boundary between the protected/unprotected sections of the part can show as that heat gradient.