When you temper a blade, what color is a good color to stop at. I have read many places that a good straw color is desirable, but when I followed the directions of the steel (01) and (5160) for 450 degrees for one hour, the blades were a deep yellow, almost purple. Did I go too far? In the end, what's more important: the color of the steel or following the directions to exact?
P.S. I use a toaster oven with 2 oven thermometers, so I know the oven is accurate.

I'd say that the temperature is the most important thing. I would think that the color could vary with atmospheric conditions, the cleanliness of the blade, etc. The temperature is what is specified for a certain steel, and that is what you should follow. Welcome to the forums!

Another thing that comes to mind is that I believe that everyone sees colors a little differently. I'm color blind, so I would never trust colors. Also, I think that a "light straw color" might mean totally different shades to you than it does to someone else. Color is subjective, temperature is not.

I agree. The color change is just one method of guaging the temperature change.

Kevin

Jeff, you are getting good advice here, those colors will lie to you. I would put my faith in the temperatures and try to get the as precise as you can. If you have a friened who can get you couple minutes access to a Rockwell tester, make some test pieces and temper them out in the range you think you should be at and then check them. It appears you are from MI, if you have no access to testers in your area let me know, Nunica is about 70 miles from Hubbardston.

All steel will have their own tempering temperatures and without some serious testing of your own, the best thing to do to get started is to follow what the manufacturer suggest. But also remember that blade cross sections will affect times. I feel that 450F. is a bit high for 5160 but not too unreasonable for O1. Also be aware that in a toaster oven your tip, and other thinner sections, or areas closer to the elements could give a slightly different hardness reading.

I believe you will find 450 degree temper with 01 is a tad hard and will leave it on the brittle side. 500 will give you a stronger edge and will still be around 57 to 58rc, in my experience. 01 requires more temper heat than most to reach a good working hardness without being brittle, and 01 will hold a respectable edge as low as 52 to 54rc. You can purchase a set of hardness testing files from Sheffield KM supply for about 75.oo. Not cheap, but cheaper than a rockwell tester, and with a little use you will learn to feel the cut of them to within a couple of points. I also believe you will find your kitchen oven will give you a better temper than a toaster type for the reasons mentioned in a previous post.