What is vinyl, anyway?
Modern records are made from polyvinyl chloride or PVC. Generally we just call it vinyl. Yes, that’s the same stuff that vinyl siding is made from. And PVC pipes. And flexible plastic tubing. And lots of other things. Vinyl is a pretty versatile material. Vinyl resin is combined with chemical modifiers and additives to give it different characteristics. If you’d like to know more about vinyl as a material, there is a Vinyl Institute website.
For pressing records, PVC is blended with fillers, lubricants, plasticizers, and stabilizers. Vinyl is clear, so colour is usually added. For transparent LPs, this is just a dye, but for solid colours fillers must be added. Black records are black because carbon is added as a filler. Some people feel that the carbon makes for better sounding vinyl. While this may or may not be true, the fact is that different colours of vinyl have different ingredients so they will behave slightly differently during the pressing process.