Fireplace Insulation

[Andy Henriksen]

I am in the process of cleaning and painting the glass doors and surrounding frame for our wood burning fireplace. (Yes, I used the high temp paint). There was a thin layer of fiberglass insulation that essentially sealed between the doors and the brink of the fireplace. It's pretty beat up and I thought of replacing it. can I use just any old fiberglass insulation, or does it have to be something special for this application?