I got good homogeneous alignment using 1% aq PVA solution. But recently, the same solution (stored in refrigerator) is not working as it used to. I have made fresh solutions but still no luck. What could be the reason ? Any suggestions on how to get good alignment using PVA solution would be of great help. Thank you

Note: baking was done at 90 C for a min and then followed by 120 C for 1.5 hrs.