Raw Material Supply and I am sure a lot of others sell a spray mold releases that I find work very well. I generally do not use it on new RTV molds, but purchase their "thinned resin for intricate molds such as people. I use the spray release on older molds and for my canoes and kayaks that use polyester/fiberglass or epoxy rigid molds. They also offer the resins in various set times so you can purchase slower set time resins or RTV for your more intricate projects.
One of the problems hobbiest often have is the offerings from craft houses is that they offer products such as Alumilite which is a medium viscosity catch all product. these, although are available in small quantities, are often very difficult to work with as they are designed to catch all hobbiest.
An internet search will produce a host of companies that sell to the small commercial model maker/artist market. Most sell 'test kits' that are very small volume suited for the hobby modeler. Granted they are slightly more expensive than the hobby kits. But, is it not worth spending a few cents more the have a model you are proud of vs 'well it will do' product after all your effort. Also, these distributors are specialist dealing with artist and commercial model makers only thus have lots of experience and can suggest the right product for our project vs the craft shop where it is an off the shelf item along with a whole host of craft supplies.