Epoxy sheeting off previous coat and fisheyes

H

Hyatt2232

New Member
Hello all,

Ive been having trouble with what appears to be contamination when spraying over epoxy that I have sanded. I cleaned the frame after sanding out some blast media with prep wipes and 710, and let sit for an hour and a half. I had no issues with this on the first coat after sandblasting the frame and wiping down with 710.

I haven’t had this issue on any of the other suspension parts I have painted, however, I did those all in one day in a small booth in my garage so I didn’t need to use the wax and grease remover at all. That leads me to think that my problem lies somewhere in how I’m cleaning the frame. I am wearing gloves through the whole process and all equipment has been cleaning with lacquer thinner. The wipes are devilbiss, and the wax and grease remover is 710. Any advice? Is it possible that I’m putting it on to thick?
IMG_1661.jpeg
image.jpg
 
Using lacquer thinner can cause some weird problems
if it soaks in to the existing finish and softens it.
Lacquer thinners leave trace elements behind and
they're not good ones.
I used it for years without problems then one
day it caused a disaster.
Maybe it was the paint I was going over, maybe a different
lacquer thinner, I don't know, but I don't clean with it anymore.
Don't know if that's your problem, but don't use it and see.
 
Looks to me like you're spraying wet/ thick/ coat with too much air pressure, or your gun is too close to the material.

This was sprayed yesterday, picture taken today after 16 hour dry time. Sprayed at 92 degrees with 65 humidity. Waited 1 hour before applying 2nd coat. Bare metal cleaned with SPI 700.

20240630_125243.jpg
20240630_125215.jpg
 
Last edited:
The two pic's appear to be the same location, is the second one after some time to cure? In the first pic it's just the classic cratering cause by what MJM mentioned above. In the second pic I can't say I remember any of my craters ever leveled out that nice.
 
What did you spray over the epoxy, is it more epoxy? how did your prep the first coat prior to spring the next coat?
 
theres no need to use wax and grease remover after blasting something, even if it has been a while, if there is no wax or grease, there is no need for wax or grease remover. the first pic looks heavy coat. if the 2nd pic bothers you, its an easy fix. just sand it with something like 180 or 220 and recoat with a lighter coat, or couple of coats.
 
Three things:
No lacquer thinner for cleaning
No prep wipes (this may have been your issue)
No need for W&G remover

I have been using crushed glass media for a while now and it cleans and preps the metal just fine. I simply blow any dust off with compressed air.
You also want to spray Epoxy Primer more like a base coat, if you lay it on too heavy, expect to see some fisheyes. A 1.4 tip works great.

Not a pro but have sprayed a lot of SPI epoxy primer.
 
Did you use lacquer thinner to clean your gun only? Or did you wipe down anything with it?

It's fine for gun cleaning, just run a little SPI reducer through the gun before loading with epoxy.

Just don't use it for any surface wipe down before primer.

And your epoxy was just sprayed too heavy. That will sand out.
 
My money is on something in the air line, or just the gun itself.
I have gotten those same things in my epoxy before, and I have done nothing but religiously prep with wax & grease and then SPI waterborne and done everything exactly as the instructions. Never used lacquer thinner in my gun. Never use any kind of prep wipes.
Nothing else touched the surface other than wax and grease remover and waterborne and then the epoxy, after letting it sit for at least 30 minutes.

The good news is that obviously sands out. Now all that said, I was using an old school siphon gun. I sprayed some yesterday with my new gravity fed and it did not do that at all. I did nothing else different other than switch guns.
But prior to yesterday, I had had those little pock marks "fisheyes" in it every time.

Same can of epoxy and activator, too.
 
Spraying epoxy too heavy will not cause that pigment migration but it is a common misconception. Barry has demonstrated this before by hammering epoxy onto the sides of paint cans before and I’ve double coated epoxy before (two coats right in a row).

Air pressure prematurely evaporating the alcohols is what causes the pigment migration.

If you want to see this in practice, do a test spray of epoxy on some paper on the wall. Now spray it again with only air from your gun, no material. You will cause the pigment to migrate and see the craters.

It helps to spray with a lower air pressure, around 20-22 PSI and be sure to observe your gun distance from the panel.
 
Thanks all for the input! To answer a couple questions, I did not clean the bare metal with lacquer thinner, only the spray gun and mixing equipment. I used that because I’ve seen it recommended here on the forum. The metal was cleaned with wax and grease remover after blasting because the truck is sitting in my driveway so I wanted to make sure it was free of contaminants before spraying. The first coat went on fine and I let it cure for one day and the wax and grease remover was allowed to evaporate for an hour and a half before spraying the second coat of epoxy. The second picture doesn’t have the same large blemishes because I let it sit for five minutes and put a light coat over it. That did even it out but I was left with the fisheyes.

Based off of the replies I’m going to try turning down the air pressure and volume, as well as the fluid. Like I said in the original post, I’ve been able to get great results on the suspension components but not the frame. I’ll attach a picture of a bracket that came out good. I’ll post an update this weekend after my next attempt.
 

Attachments

  • IMG_1642.jpeg
    IMG_1642.jpeg
    152.9 KB · Views: 122
No need to let epoxy sit for a day between coats and I would not be applying 700 wax and grease remover to fresh epoxy either. It’s simply not necessary. Tack and spray….

Don
 
Hyatt2232 said:
Thanks all for the input! To answer a couple questions, I did not clean the bare metal with lacquer thinner, only the spray gun and mixing equipment. I used that because I’ve seen it recommended here on the forum. The metal was cleaned with wax and grease remover after blasting because the truck is sitting in my driveway so I wanted to make sure it was free of contaminants before spraying. The first coat went on fine and I let it cure for one day and the wax and grease remover was allowed to evaporate for an hour and a half before spraying the second coat of epoxy. The second picture doesn’t have the same large blemishes because I let it sit for five minutes and put a light coat over it. That did even it out but I was left with the fisheyes.

Based off of the replies I’m going to try turning down the air pressure and volume, as well as the fluid. Like I said in the original post, I’ve been able to get great results on the suspension components but not the frame. I’ll attach a picture of a bracket that came out good. I’ll post an update this weekend after my next attempt.
Click to expand...
Those are bona fide fish eyes, not the cratering effect you see with pigment migration. Did we discuss water or contaminants in your air line yet?

It looks like you’re getting either a gun, water, or environmental contamination.
 
I still think it may be the Prep Wipes but another thing to consider is proper use of the Wax and Grease Remover. It must be wiped off with a clean shop towel BEFORE it dries, otherwise the contaminants just settle back down on the surface.

Personally, I put some (710) in a spray bottle. This allows me to spray it on the surface with one hand, while immediately wiping it off with the other. The shop towel will tell the story as to whether the surface is clean or not.
 
'68 Coronet R/T said:
I still think it may be the Prep Wipes but another thing to consider is proper use of the Wax and Grease Remover. It must be wiped off with a clean shop towel BEFORE it dries, otherwise the contaminants just settle back down on the surface.

Personally, I put some (710) in a spray bottle. This allows me to spray it on the surface with one hand, while immediately wiping it off with the other. The shop towel will tell the story as to whether the surface is clean or not.
Click to expand...
I second this and do the same thing. I have a spray bottle for 700 and 710. Get a small section of the panel wet first, with shop towel in each hand. First hand spreads it around, second hand wipes it before it dries.
 
I think the issue ended up being too heavy of a coat. I was using the wipe on, wipe off method so there shouldn’t have been an issue from that. My air should also be clean as I have a filter between my tank and refrigerated air dryer, and then another filter between the dryer and my coupling manifold. After sanding that bad coat down, I turned down every setting on my gun and had no issues with fisheyes or runs. However I did still have trouble with some spots that have very fine bubbles in the finish. I’m kinda thinking that may be solvent pop but I’m really not sure. Here’s the coil buckets I just did this last weekend and they have the same bubbles in the finish. Buckets were degreased, then sandblasted in a cabinet, and then sprayed with three coats 30 minutes apart. Temperature was 94° on the final coat and 86° on the first. The coating thickness is consistently 2.5 mils with some high spots of 3.5 mils.
IMG_1700.jpeg
IMG_1701.jpeg
 
You turned down your air pressure which is why it didn’t do it this time. I’ve double coated the roof of an entire camper before. That means I spray a medium coat and immediately pass right back across the same area to spray a second medium coat. It will not crater if you have low enough air pressure.
 
Lizer said:
You turned down your air pressure which is why it didn’t do it this time. I’ve double coated the roof of an entire camper before. That means I spray a medium coat and immediately pass right back across the same area to spray a second medium coat. It will not crater if you have low enough air pressure.
Click to expand...
but he does have a good bit of texture. i cant seem to replicate the flat spray out i could last fall..........i was better off not even thinking about it i guess lol.
 
You must log in or register to reply here.
Back
Top