Is cornstarch a less effective thickener when used with gelatin? Gravy is a big deal in my house, when it comes to holiday meals, so I usually make extra. A day or two ahead of time, I roast some extra turkey parts (drumsticks, wings, backs, and/or necks), then boil the heck out of them (2-4 hours). The idea here is to create a flavorful turkey stock, which would be full of gelatin. 

When I try turning this turkey stock (and pan drippings from the roasted bird) in gravy, I had to add 3 to 4 times the amount of cornstarch to get a good gravy consistency. The cornstartch wasn't "Bad", since I ran through this procedure three times with two different containers of cornstarch. I've used cornstarch in the past to thicken other things, and I know it continues to thicken as it cools, but I still think I used an increadible amount.

Does cornstarch work less well in the presence of gelatin?
Cornstarch can be a bit temperamental.  You can weaken the strength if you cook it too long and it doesn’t do well if you reheat it.  If you use a lot, it could weep.  There is a much better alternative.  ARROWROOT! (not to be used with dairy products)  Arrowroot doesn’t cloud your gravy, doesn't alter the flavor like cornstarch can.  For me, it's just a better thickener.  I use it all the time in my pot-roast gravy that has tons of gelatin and a spot of vinegar. It doesn’t interfere with the silky texture you are seeking.