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bRIBEGuy

PS Paint Problems?!?!

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So here is a new one to me...

I was working on painting a duo of bodies this weekend.  Nothing crazy, just some good old Tamiya PS rattle cans for a simple paint job.  PS-5 Black, PS-11 Pink, PS-1 White, & PS12 Silver.  Started the same way as always... wash & dry.  Mask.  Paint.  Can were warmed in warm water, and painting was done inside.  ~20 degrees C & 30% humidity.  Many, many thin coats. Hair blower on low/warm to quick dry some of the first thin coats.

So.... story goes like this:

1. Black: No issues.
2. Pink: No Issues.

Overnight drying

3. White: No Issues
4. Silver: No Issues.
5. White: BIG ISSUES!!!

I always tend to back my paint jobs with silver and then black.  On some, I'll opt to skip the black, and re-back with the main color, to add "In and Out" continuity to the body.  This was one of those cases.  But when the white got sprayed onto the silver, it started to bubble up and react, and eat down thru the paint!!!

1Zc6hI8.jpg
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I initially thought it might be a reaction with the silver paint, but when I used the same white can to add another layer to a wing (that was also white), the same thing occurred.

PL56kCb.jpg

Super not happy here.  But also super confused.

Any thoughts from the PS pros?

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No expert advice, but Tamiya PS paint is literally the only paint I've never had an issue with - and I'm not careful with it at all.  I wonder if your issue is letting it dry overnight and then going back to it?  Most spray paints either need to be recoated within an hour or so and if not you need to wait 48 hours before going back to it.  I have seen this issue with regular rattle cans and it's always when not coated immediately and not waiting long enough after the paint underneath has cured.  

The only thing I can recommend moving forward is to do all of your painting at the same time, get each subsequwent coat applied while the undercoat is still tacky, don't let it dry.  Not sure about PS specifically, but have never had an issue spraying coat after coat of PS all within an hour or so.  I usually back the PS in Rustoluem black right away as well since I prefer the inside of my bodies to be black.  Never an issue doing it that way. 

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39 minutes ago, bRIBEGuy said:

Hair blower on low/warm to quick dry some of the first this coats.

I think this is the problem. From the page I linked above. 

"Exterior heat causes the outermost surface to dry at a very fast rate. Blisters result from this layer drying before those below it." 

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That is odd.. but I too think the overnight drying may have contributed to it..maybe not..  Only when I use acrylic and PS on top do I allow the acrylic to dry overnight.   I also only use a hair dryer when painting acrylic lexan paint. 

Probably unrelated, but I usually shake the cans a good 4-5 min, I am assuming that was done. 

Sorry to see it happened @bRIBEGuy :(

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I decided to test this out gassing theory. I happen to be needing to paint a GH2 hard body so when putting on the primer, I laid it on thicker than usual (it is pound shop primer, so it is not great to begin with). After allowing it to dry for the instructed 30 minutes till touch dry, I applied a hair dryer to it, high heat to speed up the effect. True enough, tiny pin picks of bubbles appear. They are far too small to take a video/picture of without a macro lens. Now, if the solvent trapped in multiple layers of paint, it may not be just a pin hole size that shows up in the final layer. 

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Hey @bRIBEGuy really sorry to see that, I find painting issues (primarily caused by my own incompetence or impatience) to be absolutely gutting because it's really hard to row back and make them good again.

I doubt it's the drying overnight that's caused it; I always leave different colours to cure fully for 24 hours before moving on to the next colour, and have never experienced this problem

Sounds more likely to be due to the extra heat from the hair dryer, as per @alvinlwh's link and investigations above. That's the only thing in your process that isn't in mine 

Hope you manage to find a workaround 👍

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I feel like I'm being unduly rude by asking for help and then telling everyone that their help is wrong... ha ha ha, I just have a nagging feeling that the issue isn't me (famous last words, right?)...

@alvinlwh The reasons I'm fairly convinced it's not the hair drier are 1) I have used this dozens of times previously without issue, and 2) I only used the hairdryer on the first few coats.  

@87lc2 The "overnight dry has never been an issue before, but as you and @Willy iine suggested, maybe this is part of the issue?  Who know what gremlins may be creeping around the house at night... :lol:

And yes, @Willy iine, the can got uber shook up before use.  ;)

I opted to try and "fix" the issue last night, so I carefully did some sanding with 600/800/1000 grit sandpaper, blew off the dust with compressed air, and then wiped everything down with isopropyl alcohol.  Let it all dry, and then grabbed a NEW can of PS-1 off the shelf.

No hair blower.  3 thin coats.  No bubbles.

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Much better.

So what have I learned here?  Probably nothing, in all reality.  I want to default the issue to "bad paint", but the logical part of my brain keeps reminding me that the first half of the can sprayed on fine.  So that leaves user error?  Bad luck?  Improper alignment of the stars for optimal gravitational alignment of paint particles?

At the end of the day, the good news is that I think the bodies are salvageable.  The one with the worst bubbling is destined to be a runner, so if the paint isn't 100% I'm not too fussed.

Another day, another challenge...

Thanks for all the feedback and suggestions guys... whether I'm smart enough to listen to you all or not, I still do really appreciate it.

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4 minutes ago, Willy iine said:

Good to hear you are able to salvage the body, @bRIBEGuy!!

It was 5% skill, 45% luck, and 50% use of "Hope".  ;)

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3 hours ago, bRIBEGuy said:

Improper alignment of the stars for optimal gravitational alignment of paint particles?

This is the most probable explanation, there's always a strong element of crossed fingers and invocations to higher powers when it comes to paint 😂

3 hours ago, bRIBEGuy said:

At the end of the day, the good news is that I think the bodies are salvageable

This is the main thing, glad to hear it 👍

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3 hours ago, bRIBEGuy said:

Improper alignment of the stars for optimal gravitational alignment of paint particles?

Spray cans are quite hard to get right and easy to screw it up. I had been painting models for decades and still can get them wrong.

I was putting on the final coat of primer on the above body and a distraction caused me to f'ed it all up. Now I have to strip everything off the body and have a go aga, with an airbrush this time! 

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The struggle is real.  The worst part is, on some level I think that's what keeps us all doing this.  It wouldn't be quite as satisfying if it was easy to be perfect 100% of the time...

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@bRIBEGuy from your pics and description I would hazard a guess that the silver paint layer you put down hadn't fully cured in places when you put down the white on top so the "pin holes" effect was created by the gases/vapours escaping through the white wet paint. 

Glad you saved the shell. ;)

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On 11/15/2022 at 9:39 PM, bRIBEGuy said:

 

PL56kCb.jpg
 

Actually now come to think of it, I had seen this bubbling happened before, it is the propellant that stayed in someone got "mixed up" and sprayed out with the paint and continued boiling off outside. Why, I am not too sure but I suspect it was caused by spraying too close or too cold or the stars not smiling on you. 🤷

If you had decant spray paint before, you will see the paint "boiling" in the jar for quite a while. 

 

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@bRIBEGuy I decanted some spray paint for the about mentioned body using the method in the linked thread for airbrushing (as I wasted too much time on this body and don't want to f it up again with a spray can) and decided to take a video for you.

Not saying propellant boiling off is definitely your problem, but is a possibility. Also, I noticed that the fresh paint is "melting" the very (months) old paint on the straw (yes, I should have used a fresh new straw 🤷). So even paint that had dry/cured for months still will be melted by fresh paint. 

Putting the two together, a possibility is the fresh paint melted the layer below, and any propellant trapped inside that layer boil off through the new layer? 

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Oh man, that video is crazy @alvinlwh, thanks!

I think that may be the case, as I was spraying a bit closer for the last coat.  I kinda wanna dig the cans out of the trash and try to recreate this on some scrap lexan now.....

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