Endothermic atmosphere is prepared by reacting a mixture of hydrocarbon gas, typically methane or. propane and air, metered in a proportion such that there is just enough oxygen to form carbon monoxide. and hydrogen without excess carbon dioxide or water vapor.
But for your everyday run-of-the-mill deep conditioner, it should begin to work instantly, and reach maximum capacity at around the 20 or 30 minute mark. If your deep conditioner doesn't work after 30 minutes, it's time to ditch it for one that's more effective.
Confidence votes 1.0K. It takes about 20-30 minutes to actually put the color on your hair and then you have to leave it on your hair for 25 to 45 minutes, depending on the color. It should say on the box. If you leave it in longer than you are supposed to you hair will be more brittle and may break off.