You will only make light colored beer using malt that is light to start with. Look at the SRM for each grain (grain charts on the internet). A 2 SRM is very light and so if you only used grains that were 2 SRM it would be very light in color. White Wheat can be used to lighten color. Rice can also be used (whole or flaked or rice syrup). If you boil 1 hour you will not darken the beer if you cool quickly it will maintain the color but if you just let it cool in ambient temperature it will darken (not recommended).
Obvisouly the more malted barley grain you use the darker the yellow color will be and so then other adjuncts I mentioned above can be used to substitute for the barley and make the beer lighter and lighten the yellow color if that is your intention.
The BeerSmith program can show you the color of beer that you design and I highly recommend it.
Fermentor 1: Bill's House Ale II, Fermentor 2: German Helles, Fermentor 3: Bill's Schworzbier (Black Bier)
Tap 1: Bill's House Ale II, Tap 2: German Hefewizen, Tap 3: Nut Brown Ale
Future Brews: Stone IPA Clone, Blonde Ale, Budvar Clone, Newcastle Clone
New toy: Blichmann 27 gallon fermentor
“If you find yourself in a hole, the first thing to do is stop digging”
“Good judgment comes from experience, and a lotta that comes from bad judgment”