Yes, you can use black fiberglass tissue to make a floor mat. Fiberglass is known for its strength and durability, making it a suitable material for various applications, including floor mats. However, it's important to ensure that the mat is properly treated to be non-slip and comfortable to walk on. Fiberglass can be abrasive and may not provide the softness or cushioning that some users prefer. Additionally, consider the aesthetic appeal and whether the black color is appropriate for your intended use. Always follow safety guidelines when working with fiberglass to avoid skin and respiratory irritation.