Will highly reflective mylar work as a solar filter.?

I bought a roll of mylar during my growing days, and now I have moved onto better hobbies. I am wanting to observe the sun through my telescope. I have looked at some of the polymer filters that the stores sell, and it looks and feels a lot like the mylar I have. The mylar I have is 99% reflective, and when I took a snippet and looked at the sun, I didn't have any trouble, but will it cause trouble when magnified 200x?