Make dark grey appear black

Hello, I filmed a product video the other day. I used a piece of almost black foam as a background. The piece was probably 3'x5' so I had to have the product, and therefore my lighting, close to the background. In the footage, the background seems like a dark grey. Besides just making the darks darker or pumping the contrast, how can I make this appear black (or almost black)? Thanks.

Besides just making the darks darker

Does that not work?

Besides just making the darks darker

Does that not work?

To get it dark enough it makes the product to dark and blochy.

OK.

Might have to use a Mask.