I'm sure a "coat" of paint or primer means different things depending on the type, or application.
I'm more interested in knowing what is meant when shooting primer over etch as in my case.

I'm trying to get to the point of shooting Nason 421-19 primer and need to know how to "coat" it. I have a half gallon and will be shooting almost the entire body. Do I spray this primer like I'm painting, as in a light coat several times until it's totally covered? Or shoot it for total coverage the first time?
Thanks for any advice!

I'm no expert, but when we shot the primer on my car, it was one good/thick coverage coat. The idea was that it was going to be sanded and primered one more time. The second coat of primer was not as "thick", but we again shot one coat, rather than a number of "light" coats -- not sure if it made a difference or not, just sharing what we did on my car

Thanks Doug. That's more or less what I figured. That's how I shot the etch.
I was asking basically as a sanity check.
:)

I run a sanding board over the 'etch' or these days expoxy, this shows up all the low spots which I circle with a soft lead pencil..
I hit all these spot hard , then hit the whole car...then start blocking back
And repeat for 2nd coat undercoat.

That's basically what I've been doing Steps.
Over, and over, and over, and...... till my fingers have lost their fingerprints. I can't smooth a panel to save my life.
I'll be shooting the primer soon. Good or bad it's going on.
;)

Of all the cars I have blocked the 1st gen hast to the easest and fastest to get straight
Why have u lost your fingerprints ...there is stuff all blocking without a blocking board
I have 2 ..an 18 or 20" long about 1 2/ to 2" wide it has stiff but flexable base with heavy foam,,,,it is used in long diagonal strokes over the sufaces and to get body lines straight thru the car lines...one can flex it by twisting on the handles at each end to replicate the curve in panels...
And another about 10" for the smaller places
Sharp edges are shaped last.
I NEVER use those small cork sanding blocks
The only time I had sand is a quick scuff in low spots that are missed by the sanding boards.
1 sheet of sanding paper per panel, 2 for the roof and hood....

Joe,
You can do it. You just can't focus your sanding on problem areas of a panel or you will end up chasing your tail and never get it flat. As mentioned above long strokes, you are trying to feather everything out. Use a criss-cross pattern. Sand the panel in one direction and then go back over the panel sanding 90* from the first pass. You might have to do this several times. Are you using a guide coat? If not and you don't have the "feel" you will waste a lot of time and material. Finish one panel at a time until you get the hang of it, if you try to work all the areas you will get overwhelmed. Change your paper frequently, can't really say how many sheets per panel because it depend on what material you're sanding. Some primers clog or dull paper faster than others. Good sharp paper really makes the job a lot easier and the results will be a flater/smoother surface.

How you spray the primer depends on the type of primer. If it is high build you pretty much hose it on wait for it to flash and hose some more on. You can't really spray thing coeas of primer or it won't lay out flat. The temperature you are spraying in will dictate how heavy you can lay it on. If it's hot out you have to put it on pretty heavy or you will have texture/ dry spots. If you try to lay it on heavy in cool weather you will have runs and sags everywhere, you don't want that even though you will be sanding it, that is just asking for ripples.

Yeah, I let the temps and humidity dictate when I can shoot. Unfortunately the weather is changing to what it's supposed to be for this time of year which is hot and humid. I'll have to wait till evenings or sundown since I'm doing it in the garage.

I've got the technique of blocking down..... criss-cross, diagonals, etc. But I think I go too far or something. At one point I got sick of trying to fix only the low spots or repair areas and pulled filler over the entire panel. Then went to town blocking. I do use a guide coat when doing a large area.
I just have no patience for this kind of thing! :)

But I think I go too far or something
I dont bother with a guide coat....when you are up front and close with a good sized blocking boards you can see the orange peel disappear on the high spots and remain untouched on the low...
you cant flaten out low spots, only the high spots.
Only block down till the high spots get so the can just see thru it..no more..then lightly surface sand the low before hitting again with the next undercoat.

But ..and I think this maybe what you have....a low spot/dent...often a dent will have a high spot around it, making the rest of the panel seem low...this can happen when a dent is just hammered or pulled also....
The shortest distance between 2 pionts is a straight line...now if u have a dent, the metal is streached because the area between the edges of the dent is a curve.
If it is just pulled out without shrinking, that excess area of streached steel has to go somewhere...into the surounding area, distorting it....

I Think..this is why you see on TV programs they skim the whole panels with bog, in effect creating a wholenew surface above the orginal...being a lazy mans short cut, rather than fix the problem properly.

Shrinking of the areas is done by heating the center of the dent with a fine tip welding torch and working the excess steel back into the center, lifting the dent out, or using a battery and jumper leads dragged across the dent...
Both require a good understanding how metal 'works' when heated or 'electocuted'

Again, I'm no expert, but a quick tactic before painting a guide coat is that I run a little water on the area that I just sanded - it makes it look like there is paint on the car and if you look at it from a side view with the light from behind and then in front of you it helps you to see any low/high spots