Colors vary depending on application. You can get sch 40 and 80 in white.
Just realized that no one mentioned potato guns. I used sch 80 for those. That quickly leads to using iron pipe with a sparkplug and a propane fitting threaded in though.
Don't use PVC for any pressure applications like potato guns!
Agreed. Had one blow up in my hands, which kind of reduced my enthusiasm for the sport.