Awesome job on this build-a-long! I'm watching closely... 
A few of things, if I may:
Natural dyes from plants will always change color when exposed to UV rays. Mineral pigments (like the iron oxide you are using) will not fade.
Smoking a hide will not waterproof it. That is a common misconception. Smoking a hide makes it smell good and helps it to stay a little more pliable after washing. It will need to be re-smoked and stretched after each wash.
Smoking wood will not waterproof it either. However, if you use smoke that comes from a fire that is burning a lot of fat or grease, a film of grease will deposit itself on the wood and offer a little protection.
Most historical arrows were painted with mineral pigment water colors and would need to be re-painted after getting wet.
You most likely right on all accounts. On the leather that is smoked there is a deposit of creosote on the fiber that would resist water but certainly would not make it water proof as I stated. The Hide that I had at the College presentation this spring got soaked by the rain. I was sure it was ruined but I dried it out pulled a couple of times and it was good to go. I did not tan this hide but Beadman did. I guess I was think in terms of it not destroying the object. I was only wondering if there might be a similar benefit to this process. Maybe there was a process that happened naturally like a set of arrows hanging in a hut heated with wood that was often exposed to smoke. When I make charcoal there is a heavy residue that deposits on the side of the pipe that is impossible to clean easily. Anyway that was just me thinking out loud for other people to shoot down or add too. So thank you for the input and you are right it would not water proof it.
As for the dye fading do to UV that makes sense, do we see a lot of brightly colored things sitting around that has not been broken down by UV light. I was hoping to find a mix that would not break down as fast. I was hoping that the effects that plant dyes have on cloth also be useful with the arrows. My thinking was that the Acid in the Sumac plant could bite the cells of the dogwood shoot and help deliver other dyes (black berry and chock berries) into those cells as well. I have twice tried the black berry and know that I get about three weeks of color from that plant. Six months to a year before doing another application would be great in my world.
The pigments added to the egg yoke seems to be water resistant and holds up fairly good but would need to be repainted after a year.
I often over think a project (that's the cool part of the hobby for me)
In an idea world these arrow should have take game before the years end and their longevity should not be over estimated by modern people (me).
However...Egg tempera take 6 months to a year to become waterproof. The yoke is made up of water and oil. At first the water leaves and feels dry but chemical drying of the water and the harden of the oil continues for months. This may be why whitebean's friend experienced a catastrophic end to his arrows when they became wet. This is a reminder that time makes big changes in the materials we use. Tung oil take months also to cure.
I wonder what my dye would do mixed with egg. Egg was also used to waterproof ink drawings early on.
Maybe I am making arrows for next year.
The dye could be coated with the egg yoke and left to dry for a year. Question will there be any color at that point.
I dont hunt in the rain anyway.
fun stuff to think about.
