Kathleen asked:
Is it possible to color titanium in an oven (to control the temperature)? If so, what temperature does the oven have to have?
Assuming a kitchen oven, the answer is, No.
If you have a laboratory oven, a kiln, or some such, then the answer is, “Probably”.
Titanium colors by heat are controlled by temperature much like anodized color is controlled by voltage. The temperature at which you should start seeing the lowest tan/bronze is about 640°F. This is easy to reach with a direct flame, but not in a household oven.
I have not found a color/temperature scale, but would love to publish one. If anyone with a lab oven wants to play with this, please share your results.
The Mrtitanium Forum 
I follow a 7 year silver smithing course and we have an oven that goes from 30°C to 3000°C (86 Fahrenheit to 5432 F). So I’m guessing that should work somehow. I’m assuming that with higher temperature a different color will be created? Or do you think it is more the exposure time that counts?
That oven should work. As with anodizing, the color depends both on temperature (vs. Voltage) and time. If you want consistent colors, set a temperature and leave the piece in for a consistent time. Probably a few minutes at the low end. Maybe more higher up. In principle, the maximum color should be consistent for a given temperature. I don’t know about in practice.
The speed at which color develops probably depends on oxygen availability in the oven as well as how fast the piece heats up.
The chart of colors by temperature should be in the same order as by voltage. But as I said above, I haven’t seen a chart to know where the upper end (green) lies.
1040 F I believe is green. I found a chart once and am looking for it again. at too high temp it goes gray.
I love the peacock purplish blue. Trying to recreate that on a piece of armor I am making. A torch chamber seems to work good for small pieces using MAP gas. I think that propane would be fine in a small makeshift oven with the torch head as the heat supply. I am trying to make one with vermiculite insulation. Getting a consistent color would be great.
I tried this once to attempt to get around anodizing, and found that the colors quickly go from gold to dark blue through a surprisingly narrow temperature range between about 940-970 degrees. I was unable to accurately repeat colors, as I imagine time and available oxygen have a significant effect, as you mentioned is likely.