I have a variety of carbon steel pans and after I use them I dry them using a paper towel and then warm them up to make sure they are completely dry. Once I'm sure the pan is dry I spread a little bit of sun flower oil over the pan to make sure it does not rust. Sometimes the pan is hot, warm and sometimes cooled back down when I put the oil.
When I go to use the pan again (about 1 week later) sometimes the oil has become this gummy, rubbery residue.
Getting rid of it through cleaning is very difficult without damaging the seasoning. My best experience is by either heating it to the point where the residue melts and can be wiped off, or put it in the oven to bake at 250°C and basically create a layer of seasoning with it.
Why is this happening and how can I prevent this?