First Time Spraying SPI Epoxy

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PostPosted: Thu Sep 20, 2012 3:48 pm
Hey Guys,

I am getting ready to spray epoxy on my actual project, but I have only ever done Etch, 2k, Base, Clear, and SS. So last night I grabbed a scrap piece of aluminum, went over it with 80 grit on a DA and decided to test out some epoxy primer on it. The reason I am posting this up is because I am unsure about the results.

I am going to list out the steps I took, that way if there are any issues you guys can point them out.

1. Cleaned the slab of metal and went over it with 80 grit on the DA.
2. Cleaned the piece of metal with some wax and grease remover.
3. Mixed the epoxy - 1:1 and stirred well.
4. Set up the gun - Finishline FLG3 with a 1.5mm fluid tip and HVLP cap. 22psi at the gun handle with the trigger pulled fully. (By the way, it is my first time using this gun.) I always used HF guns for the 2k primers and my Tekna for the base / clear.
4. Waited 30 minutes, stirred again and strained it into the cup.
5. Tested out the spray patterns and left the fluid control wide open with the fan pattern 1/2 turn in from wide open to tighten it up a bit.
6. Sprayed what I thought was a wet coat on the panel and took the pictures below literally 3-5 minutes after the coat was applied because it looked strange. Nevermind the trash, I did this out in the open (not in a booth). I was just trying to figure out how it flowed out and wanted to get a feel for how epoxy primer worked.

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7. Sprayed a second wet coat after 30 minutes and then it started to look better.
8 Left it overnight and the below 2 pictures are about 18 hours after application.

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It is now quite smooth to the touch, but orange peel is certainly there. I was just wondering if you guys think this is acceptable or if there are settings / techniques that need to be adjusted.

Since I haven't used epoxy primer before, I wasn't sure how it is supposed to work or react and I was hoping you guys could help me out.

Thanks,

Jason



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PostPosted: Thu Sep 20, 2012 7:04 pm
I would use a 1.4 tip and up the pressure 1.5 is a little big I have used a 1.8 with the stuff but I like a 1.4 with it.
I would also open the fan all the way up make sure gun is square to panel 8-10 inches go slow but not to slow better to do multiple lighter coats than 2 heavy coats.

If I had to paint over that I would sand it out flat first.

Just my opinion
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PostPosted: Thu Sep 20, 2012 11:06 pm
Doright wrote:I would use a 1.4 tip and up the pressure 1.5 is a little big I have used a 1.8 with the stuff but I like a 1.4 with it.
I would also open the fan all the way up make sure gun is square to panel 8-10 inches go slow but not to slow better to do multiple lighter coats than 2 heavy coats.

If I had to paint over that I would sand it out flat first.

Just my opinion


Thanks for the reply.

The fan was virtually all the way open, but I just turned it in a half turn to "tighten" the pattern up a tad. I'll keep it fully open next time.

I feel like I kept a consistent distance and speed with the gun which was pretty slow, but I was unaware about the multiple light coats. I just followed the instructions in the SPI's manual that instructed me to apply 2 wet coats. I'll flip the panel over and try it again with your method, because I want to get everything right before spraying my engine bay.

Thanks again for the tips!

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PostPosted: Thu Sep 20, 2012 11:33 pm
I also use a 1.4 tip and I would up the pressure some. I treat it like a Single Stage paint - higher pressure and medium wet coats.

This is two coats unreduced:
Image
1968 Coronet R/T - a work in progress.


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PostPosted: Fri Sep 21, 2012 6:47 am
pounding the epoxy on will cause it to look funny. That looks like the majority of it. some of it still looks like some surface contamination.

Of all the epoxies that I've used...spi is definately the most sensitive to surface contamination. Over the years they've tweaked it some to cut down on it but it is still kind of sensitive. Contrary to what some will tell you, the stuff doesn't "fish eye" on its own.

I go through probably 4-5 gallons or more of spi epoxy a month. And the only time you see the problem you are seeing is from hammering the product on too wet (often with either too high of pressure or too low of pressure) It is worse at 1:1 because it is thicker. Reduce it some if you are just using it as a sealer for paint. I've sprayed it out of a 2.5 sata poly gun as a surfacer (unreduced) often with no problems.

Reducing atleast 20% seems to cut down on most of that "swiss cheese" look, which looks like most of what you have there.

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PostPosted: Fri Sep 21, 2012 7:05 am
Ok great. I will give that a try today. Do you guys think I should increase the air pressure to around 28psi at the gun or higher into the 30s or 40s?

I will also try another panel with it reduced slightly.

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PostPosted: Fri Sep 21, 2012 9:33 am
Each gun setting is a little different because of the painter's style and the product being used. How far away you hold the gun, how fast you move, the viscosity of the paint, speed of activator and reducer, etc.
You should do the spray pattern on paper set up until you "know your gun settings."
Tape some 18" masking paper (30" long) on the wall of your booth.
With paint in your gun and ready to spray hold it perpendicular (90 degrees) and about 6-8" away from the paper.
Pull the trigger full open for a one second burst. You can say 1/1000th to measure the time and then release the trigger.
You should have almost a cigar shaped pattern 8-10" long and 1-1 1/2" wide. (again this will vary per gun)
There should be no runs and the droplets should be fine and consistent in size throughout the pattern providing good coverage.
If you have runs turn the fluid control knob in a 1/2 turn at a time until there are no more runs.
If larger drops are visible then increase the PSI (with trigger open) by 2 and repeat until the paint is atomized properly.
Once you begin painting you may need to adjust slightly. Try a 12" pass on a practice panel and see how things look.
This pattern is out of an EVO4014 and is shorter and wider than my Iwata LPH400 with the same tip size but it does give you an idea of how the droplet size is consistent and no runs.
Image
1968 Coronet R/T - a work in progress.


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PostPosted: Fri Sep 21, 2012 11:28 pm
I sprayed the other side of the panel tonight with the directions given, and it was a whole lot better. I turned up the air pressure to 28 psi, and made sure I got a good pattern on the masking paper. The first coat went down much better, and there seemed to be much less of an orange peel look by the final coat. We will see tomorrow afternoon how it turned out.

Two other questions though:

1. I was cleaning my gun, and the epoxy primer is giving me a hell of a time. I flushed the gun with acetone and washed the key parts with solvent but the primer was extremely difficult to get off. Does anyone else have this problem, or have suggestions on an easier way to clean this primer. I have never had this issue with base coat, clear, or urethane primers.

2. Even though SPI recommends 2 coats, does anyone spray 3? I know an earlier post in this thread said that multiple lighter coats are acceptable but I was wondering if anyone else agrees.

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PostPosted: Sat Sep 22, 2012 10:06 am
Acetone is a poor choice for cleaner. It works okay on polyester primers but even then . . . .
Get some "cleaner grade" (its cheaper) lacquer thinner for your jobber or even a Sherwin Williams paint store might carry it.

There are guys who use nothing but SPI epoxy primer on cars and put multiple coats on but the amount of time that takes waiting for it to cure enough to sand, re-coat and wait again does not make it the acceptable course for most work.
Two coats will provide plenty of protection and from there you can apply filler if necessary or go straight to your 2k primer/block sanding sessions.
1968 Coronet R/T - a work in progress.


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PostPosted: Sat Sep 22, 2012 10:41 am
'68 Coronet R/T wrote:Acetone is a poor choice for cleaner. It works okay on polyester primers but even then . . . .
Get some "cleaner grade" (its cheaper) lacquer thinner for your jobber or even a Sherwin Williams paint store might carry it.

There are guys who use nothing but SPI epoxy primer on cars and put multiple coats on but the amount of time that takes waiting for it to cure enough to sand, re-coat and wait again does not make it the acceptable course for most work.
Two coats will provide plenty of protection and from there you can apply filler if necessary or go straight to your 2k primer/block sanding sessions.


Excellent. I will pick up some cleaner grade thinner.

Sounds good.

Sorry I'm still new at this, I'm just trying to get decent at these things so I can reduce the chance I screw up a project I really care about.
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