Epoxy Primer vs 2K for final layer - Chevelle Tech
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post #1 of 8 (permalink) Old Oct 9th, 19, 4:16 PM Thread Starter
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Stan
 
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Epoxy Primer vs 2K for final layer

Is there any good reasoning to support using epoxy for the final prime instead of 2K? I've got the car through several applications of 2K, long boarding, and repeat, and repeat. Even though I feel its really good right now and I've blocked it wet with 800, I'm considering one more 2K, longboarding with 400, then 800 before the booth. It was suggested I use epoxy for this last coat since it sprays more even than 2K, its a good sealer under the paint, and it sands wet and dry as good as or better than 2K. Any experience welcome.
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post #2 of 8 (permalink) Old Oct 9th, 19, 4:49 PM
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Dan
 
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Re: Epoxy Primer vs 2K for final layer

I'm no expert, but from my understanding is that epoxy as a final seal coat is good when you are painting over different layers of paint to get a good seal before your basecoat to prevent issues. Keep in mind that a reduced epoxy seal coat should not be sanded and used after all of your block sanding of the 2K is complete. After it's applied, you should just apply the base coat within the specifications of the epoxy. Are you using epoxy as the first coat direct to metal, or are you working over the original paint? If you are already protected underneath with epoxy, then you probably will be fine without the seal coat.
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post #3 of 8 (permalink) Old Oct 9th, 19, 4:50 PM
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Cody
 
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Re: Epoxy Primer vs 2K for final layer

Not all brands of epoxy primer sand well, keep that in mind.

I would recommend a sealer if you have any irregularities in the paint like different colors of primer showing through or if any filler is still showing. Some epoxy primer can be reduced and used as sealer. If your last coat of primer covers everything, the guide coat all sanded off, etc, you don't really need sealer. You really don't need to go all the way to 800 either for basecoat, even 600 is fine for pearl.

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post #4 of 8 (permalink) Old Oct 9th, 19, 5:13 PM
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Re: Epoxy Primer vs 2K for final layer

2 coats of SPI epoxy on top of your 2k.. let sit about 48 hours, dry block with 600-800 and shoot your color. I always use epoxy as last coat before color. At a minimum use epoxy as a sealer prior to color. Epoxy increases adhesion like nothing else will.
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post #5 of 8 (permalink) Old Oct 9th, 19, 6:37 PM
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Mark
 
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Re: Epoxy Primer vs 2K for final layer

Another option to consider is to use additive in the 2k primer and it now becomes a sealer. Check with your paint supplier as to the correct additive and reducer needed. Before epoxy was around, this was the way it was done. It's the hardener that gives you the sealing properties and is best left unsanded if possible.The same goes for epoxy as a sealer. Either will form a good barrier coat (prevents dieback) which is usually caused by the following coats being absorbed into a sanded undercoat.
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post #6 of 8 (permalink) Old Oct 9th, 19, 6:44 PM
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Re: Epoxy Primer vs 2K for final layer

Quote:
Originally Posted by Bart_Swisher View Post
2 coats of SPI epoxy on top of your 2k.. let sit about 48 hours, dry block with 600-800 and shoot your color. I always use epoxy as last coat before color. At a minimum use epoxy as a sealer prior to color. Epoxy increases adhesion like nothing else will.
This has always been my method because my projects normally sit weeks between seal and topcoats.
On my current project, I did use PPG 805? sealer and I must say, it lays down real nice. Still sanded that with 800 prior to base because it sat for again, weeks.
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post #7 of 8 (permalink) Old Oct 9th, 19, 9:04 PM
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Mark
 
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Re: Epoxy Primer vs 2K for final layer

Most sealers including epoxy's are designed to be laid down right before topcoats and should not be sanded. Sanding them technically, opens up the skim coat, allowing the top coat solvents to penetrate into the lower primer coats thus promoting possible dieback. If you cannot topcoat within the sealers dry time window, then using a sealer is not really accomplishing anything if it is to be sanded as you are just adding another primer coat. I'm not saying you can't do this, but adding epoxy and sanding it down the road is technically not the prescribed method of sealing 2k primer. If you do nothing else seal the entire surface with a very thinned down version of 2k primer and top coat within the proper window. Keep dirt to a minimum and de-nib any large trash with care.Topcoat will adhere to sealer coat by chemical reaction if kept within the proper time constraints.
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post #8 of 8 (permalink) Old Oct 10th, 19, 11:11 AM
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Bart
 
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Re: Epoxy Primer vs 2K for final layer

My method has always been:

1. Bare metal
2. Epoxy
3. Filler over epoxy
4. Filler primer (Poly or 2k)
5. Epoxy
6. Sealer
7. Color (base or single)

I always sand my epoxy prior to color regardless if I seal or not and have no issues with dieback.
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