How much primer needed to prime inside of wing spars?

I am going to prime the inside of my wing spars per the manuals suggestion. Plug with tennis balls, clean with a sloshing of denatured alcohol, then slosh with primer.... Those who have done this, any idea how much primer is really needed? At the cost of it, I really don't want to waste much....

Thanks

So, doing a little math says the inside area of all 4 spars is about 35 Sq ft. The primer says that spraying will get you 1000sq ft per gallon. A little more math says I need 0.16 quarts sprayed. I'm guessing I'll need quite a bit more for sloshing, so say 1/2 quart total? Thoughts from anyone with experience?

Mike,

Did the deed on our S7........Two variables.....1) Dilution with reducer, the more the primer is reduced, the less will adhere to the insides of the tubes therefore the less undiluted primer you will need; and, 2) Drain time - if it is cooler after the sloshing when the wings are set up on end to drain, more will drain out - if it is warmer - the reducer will evaporate faster and more will hang up coating the insides of the tubes.

Notwithstanding all of that, I used approximately 1/3 quart of primer for the spar sloshing (that is 1/3 before adding reducer). Hard to guarantee an exact amount of primer - too many variables ans it is almost impossible not to waste some with sloshing.

A person should make sure that you don't get too thick of a coating - that will invite delamination at a later date.

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp Drive

I think I used about 1/2 pint when I did mine. Just buy a pint-its the smallest amount you can buy and it will be plenty.