how long can the car set with just dp90 on it. im doing a little at a time just cleaning to bare metal etching primer and dp90. the car sets out side under a tarp. is this stuff pretty tough? can i drive the car like this for an extended period. how long do i have before i have to paint it? this may take me a long time too, and i dont want it to rust at a rate faster than i can fix it. thanks

The tarp thing is probably worse than none at all. It will hold moisture if it gets wet underneath. Unless it's breathable like a car cover.
Any primer, even a good one like DP90 has purposes. To adhere to a panel, be sandable and to absorb and 'hold' top coat. It's the absorbtion part includes water, rain and whatever is in the rain. It will eventually deteriorate, hold moisture and rust will start again. The quality of the primer will dictate it's resistance to these factor's. DP90 is at or near the top of the list for primer/surfacers.
One primer that I think would be better is Martin Senour's Tintable primer. It's a urethane primer that can be tinted in many different colors. When applied correctly, it actually has a sheen to it and I'm going to go out on a limb and say that the sheen must help in preventing absorbtion. Have you seen the older Rods with 50's retro primer paint jobs lately? They use the same type of primer for a top coat. That's what I would use if I were leaving a car in primer for an extended period of time. It would really suck to have to do it all over again.

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MY 69 (http://www.chevelles.com/cgi-bin/xchange/xchange.cgi?search_and_display_db_button=on&db_id=22&exact_match=on&photo_size=full)
My 65 (http://www.chevelles.com/showroom/JPs65frt.jpg)

I have always told shops if it sits longer than a week, do a quick sand scuffing and shoot it again with another medium coat of dp before painting. Sitting outside is not the best, but if it is, better to not be covered than be under a tarp.

Kerry
66 Chevelle

Leaving a car primed with DP90, outside is a bad idea. Especialy if the car is to be in the sun. The chemistry of DP is Epoxy. This means that there are no UV screens. If left out in the sun,it will break down and "chalk up" If you don't believe it, go to a body shop and look outside for cut off pieces of new replacement panels that have been outside for even a short time. IT's not a pretty site.In addition to this, DP does a poor job of rust prevention. A far better choice is to first apply an etch primer (such as Spies/Hecker 3688 or even 3255), followed by a urethane primer (such as Spies/Hecker 8590). When this combination is finally sanded, no sealer will be needed. If you use Spies/Hecker base coat, tinting your primer will be a waste of time and money because their base coats cover any color primer in 2 to 3 coats.

Gordon VM
http://communities.msn.com/Restorationphotos/shoebox.msnw Restoration Motorsports

hummmm. this is really a pickle. i dont have any place to put this car. some of the seals and back glass are in real bad shape and without the tarp rain water just runs in (not good for the floor boards.) when i got it, it had been under a tarp for 2 years. the trunk is in "real" bad shape. will a coat of wax on the dp90 help? or mabey WD40? it dont make sense to topcoat it and then sand it down again for a high build primer and reshoot it later.

I hope you're joking about the wax & WD. Very Very bad idea! Do you know what fish eyes are? Your paint will ahve millions of them with wax & silicone embedded in the primer.
What dosn't make sense is to prime your your car, quit working on it and store it outside.

I agree with Jimmy. Just don't stop working on it http://www.chevelles.com/forum/smile.gif As an alternative I would think if you could come up with a way to space the tarp away from the surface of the car(Something plastic maybe that won't hold water) that most of the problems that we've all seen from tarps sitting against the roof surface of cars would be reduced.

Lance