i painted my guitar but i don't know what to use to put a finish on it. i used polyurethane but it just put on a yellowish layer that didn't protect my guitar. i peeled (yes it peels off) it all off and know i need to start over.

i already looked in the painting/refinishing thread and didn't find what i need. i need a finish that dries as clear as possible. i have white on my guitar and i need it to stay white, not yellowish. i also need the finish to protect the guitar from bumps. can anyone recommend me a specific brand or type of finish i can spray on my guitar to give it these?
My Guitars:
Quote by The Needles
All the kids in the coffee houses
try to act like they know what loud is
all they know is an electric beat
if you're rockin to this, you'll be rockin with me!
Spray like rattle can? I just finished my Fender MB-4 bass with some of those House of Kolor Kustom Kolor spray cans from Wal-Mart. I used some enamel primer from Home Depot, then a black base color (2 cans), then a Black Pearl paint (2 cans), and then finished it with some clear. If you want to keep it white, they make some white pearl I believe, or close to. Enamel will work, I believe it is used in the cheaper guitars now since it is cheap to spray on and durable. Other than the HOK, Home Depot has both the acrylic and enamels so it will work. Wet sand with some 1200 inbetween coats, although I did use some worn 600 for the base coats and paint, then finished with some 1200 for the clear. Used 2 coats of each.
What kind of poly did you use? Most likely you used a wrong kind of poly. Although poly peels, it takes a while to actually break the surface. And I don't know if you know this, but Clear coats are NOT meant to protect the guitar from bumps and scratches. But You can't spray proper polyurethane without a spray gun, so I recommend using lacquer clear, like nitro or acrylic lacquer.