In my lab class this week my partner and I were making a SDS-PAGE Laemmli Gel. We made the resolving gel solution which was made of 30% Acrylamide, DI water, 1.5 M Tris-HCL pH8.8, and 20% SDS. We mixed the measured amounts into a conical vial. We then added 10% APS and TEMED and mixed carefully. We then immediately pipetted the solution into the casting stand so the gel could solidify. We then pipetted DI water onto the top of the gel so it would not dehydrate. We left some solution in the conical vial so we knew when the solution would be solidified completely. After waiting 45 minutes the gel in the conical vial was solidified but the gel in the casting stand was still liquid. How come the gel did not solidify in the casting stand but solidified in the conical vial?