Well this TIP is a tried and true one. You will have birds that will be yellowed from the sun. This is actually called "Sun Burn" but in light cases you can get around this fairly easy. In more severe cases, I recommend that you go for a "Forced Molt" but be sure and give yourself plenty of time before the show to get them totally molted and back in new feathers. Now with the white birds..Many tell you to use, Bleach, Bluing, and other such products.. These will work to some extent but they will also cause feather damage and dull the shine. I go to a beauty supply house or some Wal-Marts have this product. It's called Clairol Shimmer Lights Conditioning shampoo. It takes YELLOW away and adds sprakle and shine.. It also works well with dark colored birds.
INSTRUCTIONS: Now this shampoo is a deep purple color so I do not apply it directly to the bird.. I squirt some into a bowl and dilute it in a bit of water then put it in my hand and start working it in the birds feathers.. Shampoo it just liek you would with regular shampoo, you will have a touch of blue that remains after 3 rinses but this will fade..
Always bath white birds with this a couple times well ahead of show time and keep them out of the sun for desired results.. Than just at show time bathe with regular conditioning shampoo and Waaaaaaa Laaa you have a BRIGHT WHITE bird..
 I hope you find this little tip useful.. MaMa Gozzard