SPI Epoxy - Suggestions on how to improve finish?

Oliver

New Member
Hi,

If this was a car I probably wouldn't care much and simply sand over it. All these little rivet heads in my project make sanding however very difficult / tedious.
I am using a Devilbiss Finishline 4 with a 1.5mm fluid tip and a #3 HVLP cap.

If you guys don't mind, it would be great if you could check out the pictures I attached. Frankly, I am a bit lost on how to improve the finish / reduce orange peel.
As directed by the manufacturer, I have set the gun to 23 psi at its inlet, almost full fan. I'm spraying from distance of about 8 - 10 inches, 2/3 overlapping passes. Temperature was around 75F.
It appears that the primer goes straight from either looking too dry to too heavy with significant orange peel.

What are your thoughts? Other parts I painted in the parts looked much smoother but I couldn't really tell what I did differently.

Oliver
 

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Chris_Hamilton

Trying to be the best me, I can be
Don't spray with that gun so I'll just give you some generic things that might help. First you want to test so get some masking paper and tape it to a wall. As for your gun, Open the fan all the way. Dial in your fluid needle completely then back it out 2 full turns. Air pressure to start 25-30. Get it to where you notice it atomizing nicely on the paper. Fine mist, no big blobs (relatively speaking). If the pattern doesn't seem wet enough open the fluid needle another 1/2 turn. You want a nice wet full pattern.
Once you have that on to spraying. One thing that is contributing to the texture is you are spraying a touch far away from the panel. That gun would do better with 6 inches or so. Even consistent passes, 50-75% overlap depending on how fast you are moving the gun. If you are moving faster then more overlap. If you are moving slower then less overlap. First coat you don't want to spray SPI wet. Light medium is ideal. Second coat you can spray it wetter (but don't flood it). Mix up a batch and practice on something first. Like anything else it takes time and practice to spray it very slick.

Keep asking questions if you have them.
 

Chris_Hamilton

Trying to be the best me, I can be
Remember too if you are trying for a really slick finish that you'll want to completely sand any texture in the panel from the previous application of epoxy out. I'm sure you realize this but thought I'd mention it. 400-600 wet would be a good choice.
 

crashtech

Combo Man
In addition to Chris's excellent advice, sometimes I will add some slow reducer (10% or so) if reducing texture is important. But this will reduce gloss as well, so it may not be what you need. When used as a sealer, typically epoxy is reduced 25% or more, this significantly reduces texture and film build.
 

Jim C

Oldtimer
these guys all gave great advise. i will toss this in there though....you need to remember this is a primer, not a topcoat. while you can get it looking 1/2 way decent, if you are expecting the finish of a topcoat then you need to change you expectations and process. shoot the epoxy as a sealer then use an actual topcoat. that epoxy will turn very yellow over time anyway.
 

Oliver

New Member
Thanks again for all your responses, super helpful.

The primer will not be the final paint, I will also spray U-Tech U500 Polyurethane single stage paint as a top coat over it.

The problem are the thousands of rivet heads I have sticking out from the surface. Sanding around them is super tedious and a single accidental stroke with 320 grit paper over one can already remove the primer on it down to bare metal. That's why I want to have the surface of the epoxy primer as smooth as possible, so that I don't have to sand it much but still have a nice, smooth basis for the top coat.

I'll see if I can get some reducer from our local paint supply, I want to give this a try tonight.
 

Chris_Hamilton

Trying to be the best me, I can be
I'll see if I can get some reducer from our local paint supply, I want to give this a try tonight.
Get the best reducer they have. Tell them that. No economy stuff. Also use slow don't get medium or fast. This is important.

Also if you are topcoating it then reducing it to use as a sealer is the way to go. I'm not sure if you are using SPI (ideal) or something else, if it's something else find the manufacturer's TDS (technical data sheet) and reduce it accordingly for use as a sealer. Texture should not be an issue when reduced.
 

Oliver

New Member
Get the best reducer they have. Tell them that. No economy stuff. Also use slow don't get medium or fast. This is important.

Also if you are topcoating it then reducing it to use as a sealer is the way to go. I'm not sure if you are using SPI (ideal) or something else, if it's something else find the manufacturer's TDS (technical data sheet) and reduce it accordingly for use as a sealer. Texture should not be an issue when reduced.
Yes, I'm using SPI Epoxy Primer, but will get some other brand's reducer from my local shop to try it out. If I like it, I'll add SPI reducer to my next order. I'll ask them for the best grade slow reducer.
 

Lizer

Mad Scientist
Thanks again for all your responses, super helpful.

The primer will not be the final paint, I will also spray U-Tech U500 Polyurethane single stage paint as a top coat over it.

The problem are the thousands of rivet heads I have sticking out from the surface. Sanding around them is super tedious and a single accidental stroke with 320 grit paper over one can already remove the primer on it down to bare metal. That's why I want to have the surface of the epoxy primer as smooth as possible, so that I don't have to sand it much but still have a nice, smooth basis for the top coat.

I'll see if I can get some reducer from our local paint supply, I want to give this a try tonight.
Put tape over the rivet heads, and then wet sand with 400. It will give it a super slick, flat finish. This all is tedious, but everything to painting is tedious.
 
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