Do you mean how much clear does it take, after it dries and gasses off, to add an ounce? I don't know the answer, but even though the thinner evaps out I imagine the clear/thinner ratio comes into play somewhere...

Not that I'm a painter by trade,(I have dealt with similar coating fun-stuff in the past), but that's a bit of a hard question to answer.
You could lay a super thick coat of dope and get a lot of weight and very little coverage, or thin one and go a mile.

Also are you asking about just the paint, or in a finishing situation, where it's sanded?

For reference, the density of nitrocellulose is 1.58–1.65 g/cm3 (98.63-103lb/ft3). If you figured out your coverage area, and a thickness of dope (this would be a real crapshoot) you could figure out your weight gain. But inconistent application, and sanding between coats will make everything you've calculated wrong.

I don't either. Not unless they're sanding the living s**t out of it between coats, so most of that quart ends up on the floor.

A quart is a 946cc, but it still has a solvent in it which will gas off, and having a look at some MSDS sheets most nitrocelluloses are running at around 11-12% volume. (until I can find better info this is all a bit of a WAG).

so by that math, a quart when dry should weigh about 156g, or around 5.5 ounces when absolutely dry.

But when spraying you have over spray that does not end up on the plane, but on the floor or just in the air.

On a 700 sq inch plane, it takes about a quart of dope (mixed 60/40 thinner to clear) to gain an ounce. This is from experience shooting clear. I generally weight after each coat of clear (if using dope) and experience says it takes the entire quart, mixed with thinner, to gain an ounce.

On a 700 sq inch plane, it takes about a quart of dope (mixed 60/40 thinner to clear) to gain an ounce. This is from experience shooting clear. I generally weight after each coat of clear (if using dope) and experience says it takes the entire quart, mixed with thinner, to gain an ounce.

So, just to make sure I'm getting this:  You put a bit over a pint of clear into a 1 quart paint pot, then you put a bit less than a pint of thinner and stir.  Then you shoot the whole quart onto a plane (and half your shop), and when you're done and the plane has dried for a bit, it's one ounce heavier?

Dave makes a good point. Looking at clears that are in the 13-14% range for solids, this is the case. I've used some clears with a higher (and lower) solids ratio and so, it takes a bit more or less to get to an ounce.

And Yes Tim, I mix up about a half gallon of clear (with 60% being thinner and 40% being butyrate lacquer) and shoot it all. Normally it takes 3 or 4 coats to go through the whole half gallon. Windy used to shoot a gallon this way.