White IR Lamps vs. Red IR Lamps: What's the Difference?

I would say there is no difference.

As the output of an incandescent bulb is 95% in the infrared range the actual eye colour isn't going to make a difference.

Besides which if you are using an evaporative calculation by weighing, then there really is not any difference.

If you are trying to determine which is best, set up two identical test stations, one lamp type in each station. Place some product to be dried under each station and measure the resultant temperature rise in the product after a few minutes.

Since they both consume the same amount of power, there may not be a lot of difference. I would expect the white light to produce slightly less IR, but I have been surprised before.

Though the infrared light output between the two types may be comparable, I have found that the best visual effect is obtained by using about an equal number of red type as white type in a set-up. All white bulbs is brighter than if half the bulbs are red. But all red bulbs is annoying and hard to see under.

According to a text-book by PHILIPS, the infrared lamp with a red window is intended for therapeutical use. The output is "tuned" to peak at about 1 micron wavelenght. This is due to the fact that in this use an important factor is the pennetration depth. Only wavelenghts between 0.7 and 1.4 microns do penetrate because if shorter are absorbed by hemoglobin and if longer by the water content of tissues. The usual temperatures for the filaments are about 1900 C for industrial and 2600 C for therapeutical lamps. I guess that for drying charcoal, a good blackbody I think,the industrial lamp has advantage both in energy efficiency and life expectancy.