Bill,

Yes that's correct. All of the FX Packs are to be mixed into a Carrier Base.

Go to this link and you will see all the base colors. The one you mix the Metaliume FX into is the clear base called Trans Nebulae.

http://www.coastairbrush.com/products.asp?cat=748

Just below the clear version you will see a link for the Technical data sheet. You will see on the sheet that you mix 3 parts of base to one part FX pack (Metalume) and two parts reducer. When you mix it with the carrier base, it's tough as nails and very difficult to sand through. I have mixed the FX packs into HOK Intercoat clear and it seems to work fine as well.