Well, I'm no expert but figured I'd throw in my two cents...as for GREG HOPPE, I do not see any reason to avoid sunlight. After that you have two options...radiant heat or hot water, I have tried hot water but cannot tell you what kind of results I get because...well I really don't get any noticeable results, that and it will often times change the color of your ball (which is reversible but kind of a pain in the @$$).
My personal favorite is to leave it in my car..monitored of course...and then every few minutes wipe it off with a towel and some cleaner, wash rinse repeat until your happy. If your worried about cracking then know what does it, temperature CHANGE (this is of course for the type of cracking you would run into in this application), so if it makes you feel better then leave your piece out of your bag, in a warm room or in even in the sun for awhile then put it out there and watch sweat like a fat guy in one of those gerbil wheels
O__O wow...a little more then I meant but hey what can I say
Hammerite.