UV is what bleaches colour, so anything that stops uv will delay the fade.
But it wont stop it. Kind of like sun tan cream, its a temporary fix.
If for example, you live in the far north, you have the bowl in a dark corner of a shaded room that the sun never reaches, youre going to be fine for many years.
If you live near the equator and the sun is intense and 12 hours a day, youre fighting a losing battle from day one.
Here in Cyprus i have one wood merchant who has a fantastic amount of exotic wood in industrial quantities (he supplies many furniture making businesses). His fancy wood racks are buried so far back in the warehouse I have to take a torch with me to be able to see where I'm going, let alone look at the timbers.
The americans invented wipe on poly, you can buy MINWAX ready made (if youve just won the euro millions lottery) but its simplicity itself to make.
get a small throwaway cup, some OIL BASED (do NOT USE waterbased) polyeurathane of your choice (gloss, stain, clear. etc>) and some white spirit. Mix equal quantities of both in the cup, mix well and leave for a couple minutes to allow any bubbles to disperse. Use a small piece of clean rag, or even a piece of strong paper towel and wipe the mix over every single part of the project.
Then use another clean piece of cloth or paper and wipe off ALL the excess.
Allow to dry in a dust free area. I use a very large plastic storage container to stop dust settling on the project.
That will give you a very smooth natural look. repeat as many times as you want to give you more depth or gloss. I like gloss.
Highly recommended to use throw away gloves, or your fingers will be stuck together for days.
Cinemod... have you thought about the multi layered and coloured ply that the target rifle shooters use? I really like that effect, and it will be much easier to carve than padauk (g)
I used to be very heavily into handguns through the 80's and 90's. Now i live in Cyprus i am only allowed shotgun and air rifle, but bizarrely, only 177 air, no other calibre allowed.