u/therealbrownpaperbag

When I do my initial pass to straighten and trim my hair, my hair is silky. When I go in to curl it with the flat iron it becomes dry and brittle, especially the ends. How do I prevent this? I use the right products like leave in conditioner and heat protectant. It doesn't matter what brand I use it always happens. I thought is was split ends but it still happens when I cut inches off, helppppp 😭😭