Sealer coat or no?

[zags]

Hey guys,
I used PPG DP50LF epoxy primer on my 40 after media blasting and I am currently block sanding coats of PPG K36 acrylic urethane primer surfacer on the exterior of the body to get everything straight. I have read that it is optional to do a final sealer coat of epoxy prior to shooting paint. The paint will be single stage PPG Concept DCC acrylic urethane. So, why is it optional? Is it best that I do it, or does it really matter?

Thanks!

 

[toomanytoyzz]

If you are going to spray the color over the K36 you better make sure it's been thoroughly wet sanded with 600. You can also use DP50 as a sealer. Just follow the tech sheet which will tell you the mix ratio if being used as a sealer. Most are the same 4:1 (4 parts primer to 1 part hardner) ratio but they also require using 10% urethane reducer. It's been awhile since I've used PPG's DP series so don't quote me on those numbers. I'm going by the brands I'm used to.

What color are you painting the vehicle? This is usually when I opt to do a sealer coat. For instance, if you use a yellow tint primer and are going to paint your truck red you better seal it with a gray color or a more comprimising color or else you will have ALOT of bleeed through requiring more coats which equals more $$$.

 

[zags]

The color will be fashion green (sage green). I am using grey primer.

 

[toomanytoyzz]

You will be fine with that color combo. The green will cover over nice, BUT like I said in the other post if you are not using a sealer make sure the K36 has been wet sanded to remove any imperfections. This can become a grueling task especially if you have done alot of bodywork and it is not 100% even. What happens is you will expose the highs and lows on the panel during wet sanding. Excessive sanding can and usually results in cutting down the primer to bare metal in certain spots not 100% flat. These areas must have primer over them before putting the color down. This when you should use the sealer since it doesn't require sanding before applying any color.

 

[FJsnoozer]

The above post is exactly how my build is going.

Skim coat and air filed. This sanded through in some areas



I sprayed epoxy then topcoated with high build epoxy



Blocked to 400.



Topcoated with epoxy. I am going to sand one more time to a fine grade and topcpat with epoxy. Reduced 10%

 

[Splangy]

You can dry or wet sand the k36. I would then spray a sealer coat of thinned DPLF and spray the color over the freshly sprayed sealer.