Can you put on too much epoxy on too fast?

[jtfx6552]

I put white epoxy on some fenders tonight. Due to some spidering on the initial coat, I didn’t get two “clean” coats.

I ended up kind of hosing it on once it got tacky to get coverage. Ended up with some runs, and some spots that are still spidered. Wondering when I can do another coat to cover the spidered spots that didn’t get completely covered.

 

[Chris_Hamilton]

You should always wait at least 30 minutes between coats. You can wait longer as well. You can come back the next day and shoot more coats. Curious as to what you mean by spidering. Did you spray over bare metal or an existing finish?

 

[jtfx6552]

You should always wait at least 30 minutes between coats. You can wait longer as well. You can come back the next day and shoot more coats. Curious as to what you mean by spidering. Did you spray over bare metal or an existing finish?

Bare metal and scuffed e-coat.

 

[DanMcG]

Do ya have a pic of the spidering? I'm new at this and not familiar with the term.

 

[dhutton01]

I guessed spidering means craters.

Don

 

[jtfx6552]

I guessed spidering means craters.

Don

Yes. initially the craters were bigger than the areas of paint between the craters, kinda looked like a spider web. After another coat, I have decent coverage in spots, still craters in others, and a couple sags and runs.

Wow, the pictures look terrible, embarrassed to put them up here. In the pictures, the fenders look grey like there is not full coverage. Might be a camera issue there, in person they are very bright white, at least where there isn't still deep craters down to the ecoat.

 

[dhutton01]

Curious what the temperature was. Did you check temperature of the panels?

 

[jtfx6552]

Curious what the temperature was. Did you check temperature of the panels?

Yes, was 80+ on the fender closest to the mini split, 75 on the one further a way. I did shut the mini split off while I was actually spraying. Turned it right back on as soon as the overspray was cleared.

 

[dhutton01]

White is the worst color for cratering in my experience. Have to go light on the first coat. I would sand the worst of that before applying more.

 

[DanMcG]

I certainly recognize your "spidering", I've had my fair share of them. You can't hose it on, especially on the first coat. What are your gun settings?

 

[64avanti]

Cratering has been discussed many times on this forum. It is caused by laying on the epoxy too thick, especially on the first coat. I learned to spray a scrap until it cratered, then back off just enough to not crater. This way I could still lay a good coat of epoxy, not so thick it cratered, not so thin that it was dry.

Trial and error. But once I got it figured out, I have gotten pretty consistent with it.

 

[jtfx6552]

I certainly recognize your "spidering", I've had my fair share of them. You can't hose it on, especially on the first coat. What are your gun settings?

Cratering has been discussed many times on this forum. It is caused by laying on the epoxy too thick, especially on the first coat. I learned to spray a scrap until it cratered, then back off just enough to not crater. This way I could still lay a good coat of epoxy, not so thick it cratered, not so thin that it was dry.

Trial and error. But once I got it figured out, I have gotten pretty consistent with it.

I think my fan was too narrow when I first pulled the trigger. I widened it up and things went a little better. However when I first pulled the trigger it was instant crater.

I reread the tech manual and see where it says to only use water based 700-1 W&G remover. I had used the 710 solvent based, but I did wipe it up, didn't let it dry on there. I'm wondering if that contributed? And if it did, do I need to sand everything off?

Or should I just sand the rough spots and add another coat? And if I do that, how do I guess when it's cured enough for sanding?

 

[64avanti]

So the cratering is too wet of a film.

Since I only use the waterborne W&G I can't help with that.

SPI epoxy powders when you sand it. If it is not powdering, then it's not dry. If it's not powdering after overnight dry in minimum 65°, you've got a problem.

 

[AAE]

I think my fan was too narrow when I first pulled the trigger. I widened it up and things went a little better. However when I first pulled the trigger it was instant crater.

I reread the tech manual and see where it says to only use water based 700-1 W&G remover. I had used the 710 solvent based, but I did wipe it up, didn't let it dry on there. I'm wondering if that contributed? And if it did, do I need to sand everything off?

Or should I just sand the rough spots and add another coat? And if I do that, how do I guess when it's cured enough for sanding?

There's always residual solvent from the cleaner. You should let it flash for a good while, 30 minutes is kind of the standard. Or, blow air over the area to help dissipate the solvent.

 

[jtfx6552]

So the cratering is too wet of a film.

Since I only use the waterborne W&G I can't help with that.

SPI epoxy powders when you sand it. If it is not powdering, then it's not dry. If it's not powdering after overnight dry in minimum 65°, you've got a problem.

I did some sanding with 150. I sanded out the run on the front of the drivers fender (photo 3570 above). As expected for me anyway, the run was not fully cured, but underneath it, and around it seemed to powder up nicely.

Is it safe for me to sand out the cratered areas and shoot a couple more coats?

 

[1A Rock]

I did some sanding with 150. I sanded out the run on the front of the drivers fender (photo 3570 above). As expected for me anyway, the run was not fully cured, but underneath it, and around it seemed to powder up nicely.

Is it safe for me to sand out the cratered areas and shoot a couple more coats?

As far as I can tell, there is no limit as to how many coats of this epoxy you can add. Just make sure that the previous coat has flashed off good. after 2 coats I wait at least an hour or more between coats.

 

[Lizer]

If you get craters, you can sand it within 1-2 hr if you wet sand with 710 WGR. Wet the paper with it. I use 220. It works well.

(No I didn’t invent that. It was advice from the Barry).

 

[jtfx6552]

If you get craters, you can sand it within 1-2 hr if you wet sand with 710 WGR. Wet the paper with it. I use 220. It works well.

I did some sanding, will try the wet sand trick.

3rd and 4th coats went on well. I guess the good news is white gives good practice at keeping the gun moving. What I did tonight, made sure to more thoroughly mix the epoxy right before spraying, and checked the gun pattern on paper first. I'll see how this drys.

 

['68 Coronet R/T]

I think my fan was too narrow when I first pulled the trigger. I widened it up and things went a little better. However when I first pulled the trigger it was instant crater.

I reread the tech manual and see where it says to only use water based 700-1 W&G remover. I had used the 710 solvent based, but I did wipe it up, didn't let it dry on there. I'm wondering if that contributed? And if it did, do I need to sand everything off?

Or should I just sand the rough spots and add another coat? And if I do that, how do I guess when it's cured enough for sanding?

You should set the gun up using masking paper taped on the wall.
This will ensure you have the proper fan size and the gun set up properly for proper atomization.

When doing a thorough cleaning of the gun, it is easy to get things out of whack, so I always recheck my gun settings by doing a quick test spray on paper. Notice the varied fan size patterns.

A quick 1 second pull on the trigger will let you know immediately if you have issues.

 

[jtfx6552]

I originally put on white epoxy to be followed by black, so I can see when blocking if I'm about to break through.

Put two coats of black epoxy on twice, a day apart, blocked after the first two coats.

Last two coats dried overnight, and I can see some sanding scratches. I used 180 to block, so I'm not sure why that is.

In any case, I mixed up enough for two more coats, was going to block just a little to see if there are any highs, then hit with a scuff pad to make sure all the sanding marks are gone, then reshoot two more coats.

Below are some pictures, last picture shows a glove print, I backed my ass into the fender behind me when starting the second coat on vendor 1, just managed to grab fender 2 and keep it from falling. I'll smooth that mark out as well.

For future reference, I have about 2 ozs in each dekups liner from Thursday night and Friday night's shoot, could I mix that in with what I just mixed up this morning? Since I wasn't sure I mixed up enough today that I don't need to.