Bill:
My problem is that 4 ounces of paste is all I need as a gallon of silver will last me a long, long time.
I guess I shouldn't have tried switching dopes; but I found SIG to have too little pigment and bad coverage in their whites and creams, and Brodaks doesn't like fuel on it at all. I had read that Certified was better than Randolph's, but they have very limited colors. Seems like I'm always searching for the "magic bullet". Oh well.
And even smarter - I've got three coats of Certified butyrate clear on my newest plane (but shoulda checked on the silver issue first - oh! oh!) 
Scott
"My problem is that 4 ounces of paste is all I need as a gallon of silver will last me a long, long time."OK, so mix 1 ounce of paste with a quart of clear.
"I had read that Certified was better than Randolph's"In many years of using both Certified and Randolph I have never found that to be true. They are equivalent in quality and are completely compatible with each other.
"(but shoulda checked on the silver issue first - oh! oh!)
"So just buy a quart of Randolph M-9514 Silver which shows as $22 in the latest Aircraft Spruce catalog (price may vary some, look at their website for latest pricing.)
Another thing about butyrate thinners - I have found Certified thinner to be the fastest drying, Randolph the next fastest drying, and Sig to be the slowest drying. I occasionally blend thinners to achieve the drying rate I need.
As far as different colors of silver, on my paint mixing system there are three different silvers differing in the size of the metallic flake. Different colors of silver are made by adding tint colors to the metallic silver - adding just a bit of black to the blue (there are several different blacks, by the way: black to the blue, black to the yellow, black to the green, pure black, etc.) If you are tinting the silver and you want to have the maximum metallic effect then use a semi-transparent tinting color. For instance, adding straight white tint to metallic silver greatly diminishes the metallic effect.