why do I have to use butyrate primer?

[paulwells66]

Was looking for butyrate primer on Brodak's site and they're out of stock. Randolph doesn't list it at all. Why do I need to use primer under a color such as white or black?
thank You

[Howard Rush]

Here's how the Jive Combat Team does it: http://flyinglines.org/ptg.finishing.html

[paulwells66]

Here's how the Jive Combat Team does it: http://flyinglines.org/ptg.finishing.html

looks nice!

[paulwells66]

You don't. You can use nitrate UNDER Butyrate but NOT on top. Clear, with a small amount of tint, (thinned dope of the color you intend to finish with) can be used instead. Mainly primer is used to cover every thing so there is an even coat for the colors to go on. No grain or fillers show this way.  Some primers also act as a filler.  A white primer makes red and yellow brighter than a gray primer, which can make those colors slightly darker in tint.

thanks!

[John Lindberg]

You don't. You can use nitrate UNDER Butyrate but NOT on top. Clear, with a small amount of tint, (thinned dope of the color you intend to finish with) can be used instead. Mainly primer is used to cover every thing so there is an even coat for the colors to go on. No grain or fillers show this way.  Some primers also act as a filler.  A white primer makes red and yellow brighter than a gray primer, which can make those colors slightly darker in tint.

I agree with Ty, light colors for the primer (I use Rustoleum Car paint primer,in a spray can, light grey, I get it at Wal-Mart, or Home Depot) make the top color brighter. I use mainly nitrate dope to fill the balsa grain, then the spray primer. I have a lot of nitrate sitting around, mainly because I like to build small free flight models. The nitrate does not shrink the structure as much as Butyrate, at least that's what I have been told! In other words, you do not have to use butyrate primer. 

[Dennis Toth]

Paul,
If you are going to use Butyrate dope for your colors you should use a primer that is solvent based. Don't use an enamel primer as the dope will not be compatible and it will not stick well. Use one that dries in 15 minutes and uses solvents not mineral spirts for clean up. You can use clear mixed with some Zinc Stearate (from Randy Smith) to do the filler then use either polar gray or silver as the base. Some like to use a final block coat of Dania Cream. You do want to get a solid base color (unless the base is black) to have even color.     

Best,   DennisT