Ester foam insert and isopropyl alcohol I recently purchased a used set of lens for my telescope. They came in a nice aluminum case with foam inserts, but the foam has an odor. I am currently using just the sun to try to rid the foam of the musty odor. It's slow going. I was wondering if there would be any adverse interaction if I sprayed the ester foam inserts with isopropyl alcohol? I am hesitant to spray anything on the foam for odor removal, for fear any lingering residue may harm the lenses in the long term.

The foam looks like a gray ester poly foam. Bottom is solid, top is convoluted.

Thank you.
I would just try soap and water first. If you want to try any kind of solvent like alcohols, you really needn't be concerned with lingering smell, but I would be concerned with the (slight) possibility of destroying the foam. 

If soap and water doesn't work, just try placing a drop of isopropanol on both the top and bottom of the insert and let it dry. If there is any change in the consistency or feel to it I would stop there. If not, then progress to cleaning a small area, and if that does no damage go ahead and soak the whole thing if needed.