Fireproof Archival Storage. No Ball Cubes.

[David Atkatz]

I am considering buying a very good, very expensive, fireproof safe so that I can store some of my collection at home, worry-free.
The safe can withstand two hours at 1850º F, with the interior temperature rising to no more than 350ºF, well below paper's scorching temperature, and well below mylar's melting point. So my flat items, which are stored in mylar sleeves for protection, should be fine.
But what about baseballs? The baseball itself has no problems, but ball cubes are a different story. This is what a ball cube looks like after a brief time at 350º:
(I have just purchased archival cardboard and mylar baseball storage boxes.)