I like black velvet, it does not reflect light as much as some fabrics.
Do you use just any black velvet you can find?
I buy mine from a Fabric store named Hancock Fabrics. I think they are all over the US. Its very deep black, and very expensive. However, you can signup to have them mail coupons weekly or bi weekly, they often have a 50% off one item coupon. I mostly use white velvet, but have black, white, green, purple, blue, and some other non velvet colors. I use clamps to clamp fabric to some 3/8 stiff construction foam boards which I can store easily. I have two of each, one for a vertical back and one for the work top. I can use two different colors as well.
This one is not velvet, but a example of two different fabrics. I think it was taken with my Nikon CP-990 and a high wattage Tota light about 2001, so the resolution is not up to todays bodies. That was a wonderful camera, and was expensive.