Do I need to seal or what, confused?!

[wickedpty]

Ok, I have a 68 stang. I just got done wet sanding the whole car with 400. I was sanding PPG primer. I am nt planning on painting for two weeks. Do need to seal this or what. Someone told me it will rust if I dont. If I use sealer, do I have to wet sand 400 the car again, that will suck. Or can I just leave it alone and be k. The car is garaged in a southern california climate right now. Please help, thanks in advance.

 

[fastblueheeler]

Wicked, I've got the same question so I'll piggy back on yours. I'm doing a 76 Corvette. I've primered with Omni primer and am in the process of blocking it. Wondering about using a sealer before the base coat and do I sand the sealer? Sorry I couldn't help.

 

[wickedpty]

sweet, we can both learn then, how are you blocking??? what type of paint are you gonna use, 2 stage or 1 stage.

 

[fastblueheeler]

I'm pretty new to this but from what I understand to be right I'm shooting the primer, then spraying a guide coat of cheap rattle can primer of a different color lightly over it. Then wet sanding till the guide coat is left only in the the low spots (the areas the cheap primer stays on) so you can fill them and sand smooth,then prime again. I just started the blocking yesterday. I started with 600 sandpaper but that was going real slow so I switched to 320. After the blocking you spray another coat of primer and sand again. On the last sanding I think I'll use 600 but not sure this is necessary. I'm using a paint stick with the sand paper wrapper around it on the striaght flat areas. I've read a lot about the sealer. Some recomend it others don't? I'm using 2 stage Omni paint and clear coat. Lots of work - good thing I don't have a job!

 

[wickedpty]

Sounds like you are doing exactly what i am doing. but i am sanding with 400. I should say, wet sanding with 400. same with you?

 

[fastblueheeler]

I'll be wet sanding with 400 also. I had some 320 so I used that but I think 400 is recommended. Still wondering about the sealer. we need a vet painter to jump in here.

 

[rex]

This is just my opinion but I wholeheartedly believe in a sealer to to give you a uniform color to cover and to minimize the sand scratches.600 isn't a prob but 400 is a touch rough to base directly over I think.

 

[wickedpty]

So I should 400, then seal, then sand again??? If I seal it, then wait a couple of weeks, how do I scuff prior to painting? Do I need to wet sand it all again??? that would suck

... Thanks Rex

 

[crazycuda]

The type of primer will make a differance. if you are using a epoxy or urathane primer that is non moisture abosrbent (ppg k36 or dp40) you could get by waiting on the sealer.

the best way to do it is do you final wet sanding just prior to sealing and paint.

The sealer is used to prevent any of the bottom coating (paint or body work)from bleeding to the surface and showing up in the paint. Also the sealer helps to fill any minor scratches left from the final wet sanding. There are a fiew multi-part primers that do not need a sealer applied over them but most of them are designed to be used as a final prime coat / seal coat and they really don't build well. Example ppg dp40lf. The only problem with the dp primers is you only have a window of 7 days to topcoat or you need to resand the surface and prime again.

 

[rex]

Sorry guys,I've been on a free drunkfest for a few days with the wife's boss and employees.Back to the Q,as long as you dont have bare steel or very thin primer spots it'll hold just fine until you get back to it,just keep it in the garage out of the weather.This doesn't count for lacquer primer though.You can seal it and let it set but you will have to sand it if you wait too long so I prefer to seal right before I paint or the night before.For DP or the NCS 2000 line of sealers the open time is 7 days at 70,so you still have 3 or so days at 85.All sealer specific primers can be painted wet on wet meaning no sanding required unless you want to nip out a dirtnib.If you do seal and run out the time you can either wet 600 it if it's filthy or you can wet scuffy it with a grey scotchbrite.Technically you're supposed to reseal it but you can base it-all you need is scratches to open up the surface and give the paint some tooth to grab on,the reducer will also penetrate the sealer some to add chemical adhesion.Oh,on the guidecoat blocking.When you have most of the guidecoat off and see the lows,feel them with your hand.If you can't really feel them keep blocking evenly until they're gone or you hit metal surrounding the area,same applies with bondnce you hit steel it's time to stop and reapply.When my last blocking has all lows and imperfections gone and there are spots here and there of steel or the primer is so thin I can see the steel then I lay my last 3 coats down for final sanding.On this sanding only take out the scratches from the last sanding so oyu keep most of your primer on,about 2 of the 3.