I have just finished sanding Rustoleum primer/filler off.  It was applied over nitrate.  My questions are:
1. Can I put nitrate clear over Rustoleum.

2. Should I shoot one more coat of primer that is lightly sanded but not sanded off before going to base coat and if not, is dry sanding with 400 sufficient.

3. Ball Park - How much weight does a normal (not mist, not wet) coat of Rustoleum weigh on a 700sq" ship (attachment).  I am at 62oz fully loaded with a 6s battery as it sits.

4. What to use for "Rattle Can" clear coating?

Thanks - ken

For rattlecan clear this is what you want.

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How long does it stay usable in the can?  Will one can do all three coats?

ken

   For an electric model, why not just stick with dope or acrylic lacquers the whole way through and make it easy???  You have no fuel resistance worries, and an all dope or all lacquer finish will be the lightest you can get and be the easiest to repair. I don't understand this desire to have a Heinz 57 variety component finish?  Especially when it's not needed!
  Type at you later,
  Dan McEntee

   For an electric model, why not just stick with dope or acrylic lacquers the whole way through and make it easy???  You have no fuel resistance worries, and an all dope or all lacquer finish will be the lightest you can get and be the easiest to repair. I don't understand this desire to have a Heinz 57 variety component finish?  Especially when it's not needed!
  Type at you later,
  Dan McEntee

On a dope finish, I would brush on a light coat of clear after sanding off the filler to seal the dust trapped in the pores.  That is what the primer question was all about. Everybody says don't use Rustoleum clear and I am certainly not going to pop the top of a 2k to seal the filler.  So I guess the answer really is just another shot of primer. 

It is strange that of all the forums, the finishing one is where you are least likely to get an answer to a question and most likely to be criticized for asking one.

Ken

You sanded the primer back down to the nitrate and now you're going to shoot another coat of primer? Is this a different kind of primer or was the first primer not good?

First coat was Prrmer/Filler.  I guess my next coat will be plain primer.  I was going to use nitrate clear to lock in the dust but primer is just as good for that  and probably lighter.   Any idea how much a coat of Rustoleum weighs after it dries?

Ken

Ken, in all seriousness, don’t entertain the idea of nitrate dope over the Rustoleum. Only bad things can happen.
You have a big plane, so another complete coat of primer that you don’t intend to sand off is going to add weight you don’t want. Exactly how much weight is difficult to say, but probably at least a half ounce. So if you REALLY think you need a lockdown coat, do it thin as possible with Rustoleum. Maybe even Rustoleum clear since you don’t need fuel proofing for electric.
If the model is ready for color otherwise, My advice is to clean the model thoroughly and go right into your base color and go from there. Hope it works out.

This is what I was after.  I have never had the pleasure of a non dope finish (I have been doing this since about 1955) so I am a rookie at this.  My routine was simple. Tissue on the fuselage, silkspan on the wings.  4 coats of clear, sand with 400 till smooth then start adding "X" filler coats (dope and OMG Talcum Powder) until all of the low spots were filled sanding all of it off with 400 except where it actually "filled".  One more coat of clear with a bit extra where there was an abundance of filler and all of this was brushed..  Wet sand with 600, let it gas out a couple of days and go to color.  Life was good.

I should have stayed with this but the only "Dope" at our local hobby shop was the guy behind the counter so off we go to Home Depot.  I used pollyspan since there was no more silkspan (I found out later you can get it if you have good credit) .  Really easy to cover but lord help you if you sand into it.  4 coats of clear and everything looks good.  I used gray Rustoleum filler followed by white Filler/Primer.  I am not sure that the Primer is the same base as the Rustoleum color but it is compatable.  If I go to color directly I will be hitting places where I am sanded down to nitrate or z-poxy.  That is why I wanted another coat of primer in my base color (white).  However, enamel should stick to all three so maybe I don't need the primer EXCEPT that I still don't have a consistent  base color coat to examine for and correct flaws.  I fly them at this point and I have already flown this one.  It resulted in major surgery to correct control issues.  The scars from the surgery look and feel like they are covered but you don't "really" know till you hit them with color.
That is a very long winded explanation of why I am conflicted over what to do next.

1/2 oz is still in my weight budget.  I have 8oz to go before I have to register with Weight Watchers.  6 is my goal.  I am guessing that color is heavier than primer.  2 coats color, three coats clear.  The good news - next time won't be the first!

This is my 1st .60 size ship and if the test flights are any indication, I will be able to easily make up the 5 points or so I give up on the finish by the time I am done with the loops.

Thanks - Ken

Maybe do a little spot priming in the needed areas rather than blast the whole model? That’s what I do when I get a few trouble spots. Like you, I usually do dope finishes because they’re light weight. I don’t know that the Rustoleum primer is any lighter than the color. If I had to guess I’d say it’s heavier due to more solids in it. Maybe??? Either way, paint weight sneaks up on you and I’ve done enough Rustoleum finishes on some sport models to know the stuff gets heavy pretty quickly. So use sparingly.

Edit: still better to have a few grams of extra paint on it than it is to sand into the Polyspan! That becomes a nightmare!

Sometimes a picture is worth 1000 words.  I have thought of just going directly to clear,  use military markings and telling everybody it is a new camouflage.  FYI what you see is rock hard and glass smooth.

I think one coat primer and just sand off the fuzz with 600.

Amen to sanding into polyspan.  That is a HUGE no-no.  So far I have only had limited success with CA and z-poxy.  Both are difficult to flair back in.  I did get one patch to appear to be fixed by rubbing in plastic wood.