Make sure you mix the putty well to one even color. Then make sure you keep the tray in your mouth the whole 3 1/2 minutes. If the putty is still too soft, you can get drag marks upon removal of tray. Drag marks mean we can't use your impressions. Yes, even tiny drag marks mean we can't use your impressions. You want comfortable aligners right? So wait. If you lose track of time - make it longer. 4 minutes? No problem. 5 minutes? No problem. 3 minutes - problem. :-). Good things come to those who wait.