Do it yourself painter?

[9 Lives]

I have layed 3 coats of primer on the truck so far (bare metal)



Do I need to sand the primer before I start to lay the paint?



Im using Dupont primer & paint. 4:1 ratio is what the guys there have told me.



I have read a bit online and have gotten mixed ideas. One guy mentioned sanding inbetween each coat of primer. Then another said 3 coats of primer then wet sand & start painting.....

 

[9 Lives]

Also a little curious as to what grit paper I should use to sand the primer before I paint? And just how much do you sand before its to much? just till its smoothe? or scratching right?

 

[GOlsen]

Yeah, you're going to want to do some sanding before you lay the basecoat. Use a 600 grit sandpaper to make the surface uniform Use a light touch, you don't want to groove the surface or create scratches that will show through the paint. I could go on about this for a while, but hopefully this will get you pointed in the right direction.

 

[HSpiering]

Some primers you sand. Some you don't. What type you have? Did a paint job myself and used primer DP-40. Two part. Painted 1hr later. Gave a bond that you could never separate.

 

[GOlsen]

There are some systems like that, but they are designed for that. There's also not that many of them. Dupont doesn't make a system like that, unless I'm mistaken. Also, you have a limited "window of opportunity. " If you go outside that time frame (usually anywhere between 30 to 90 min), you have to sand after about 24-48 hours before you can lay a basecoat or sealer to have optimum results. And since you're already paying for the paint, which isn't cheap, might as well do it right.



Also, depending on the colors you use, if you use a system that's not designed to be sprayed on top of each other right away, you can have bleed through. That sucks because you usually have to take it all the way back down again.

 

[Hoefler]

Also a little curious as to what grit paper I should use to sand the primer before I paint? And just how much do you sand before its to much? just till its smoothe? or scratching right?

You can guide coat it. You take a fast drying paint, lacquer, rattle can, or any thing cheap and lightly coat the surface, Then sand it until it is all gone. It will show all the scratches as you sand. I would nothing finer than 400 wet, anything finer you may risk an adhesion problem. If you are using a urethane or epoxy paint, they work better on a rougher surface. I shoot Dupont's 2 part paint over 320 sanded primer.

 

[GOlsen]

I agree with the guide coat, it's not always necessary, but a good idea. As far as what grit sandpaper to use, you're always going to get some sort of controversy. :-{} I have always used 600 wet and never had a problem with adhesion. I've sprayed DuPont, PPG, House of Kolor, and Matrix systems and have never had a problem. The problem with using too coarse of a paper is the fact that's it's less forgiving for a beginner. It's easy to remove more material than you want, and also easy to put grooves in your surface if you're not familiar with proper technique.

 

[RacinDuallie]

Longboard it using a crosshatch pattern while sanding, start with 600-800 as a starting point. And light, even pressure on the longboard again sanding in a crosshatch motion... ...

 

[9 Lives]

The color is Brandywine... . love it Can't wait to see it over that primer just want to make sure it sticks real well.



Ive done 3 coats of primer and havent sanded yet. I more than likely won't get the chance to lay any paint till first week of January due to family issues & holliday. Should I lay another coat of primer the day before I paint and sand that really well as you guys have described?

 

[BimmerAgent]

What're you painting ? Bruce

 

[9 Lives]

Im painting a single cab 4X4 truck.

 

[Hoefler]

The color is Brandywine... . love it Can't wait to see it over that primer just want to make sure it sticks real well.



Ive done 3 coats of primer and havent sanded yet. I more than likely won't get the chance to lay any paint till first week of January due to family issues & holliday. Should I lay another coat of primer the day before I paint and sand that really well as you guys have described?

Since you are waiting awhile to paint it, I would suggest you seal it when you are done sanding. Primer is porous, depending on you humidity and temp, it can draw moisture causing it to rust under the primer. A good sealer will seal it and you just need to scuff it lightly to prepare it to paint.

 

[GOlsen]

Since you are waiting awhile to paint it, I would suggest you seal it when you are done sanding. Primer is porous, depending on you humidity and temp, it can draw moisture causing it to rust under the primer. A good sealer will seal it and you just need to scuff it lightly to prepare it to paint.

I definitely agree.

 

[EdK]

Before you shoot the color coat, have you grounded the truck? An ol' timer told me to always ground the vehicle, especially if you are painting in your garage. It seems spraying the paint causes static and that will "suck" dust onto the vehicle... especially from your clothes.



Ed

 

[Champane Flight]

Clean clean clean....

Make sure your air is clean, your surface is clean, your painting booth or garage is clean, everything in the garage is covered, you wear a mask, and tyvek. What really sucks is to finnish up and have son throw open garage door, right over truck! I just handed him the sand paper on the way out in tears... . Had an oldtimer once tell me it was better if you did not have a spray booth to do it outdoors on a calm sunny day...

 

[daveshoe]

guide coat

I know a hotrodder that paints alot and he cautioned against using any old thing for a guidecoat. Some of the modern primers could react with some paints--not good. He said that he uses red and grey primer of the same formula to do the guide coat thing. You sure do not want the guide coat to melt in and react with the primer and cause an unseen problem until you apply the finish coat.