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Mythbuster--Red "Bleed"


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This isn't a question, nor is it a tip or tutorial, so I guess I belongs here.

Did this test piece a couple months ago when someone said his clear coat had cased red pigment to leach out of the plastic and ruin his paint job.

Piece is a very red interior tub (underside) from an old Monogram '65 Mustang 2+2. I put one wet coat of cheap Walmart house brand gray primer on it, then masked half of it off and gave the other half one wet coat of cheap Walmart house brand white primer. When that was dry, masked off half of both halves and shot a real nice wet coat of whatever clear was being talked about--I forget If it was Testor Wet Look Clear or Krylon clear--to see if that caused any color bleed.

The pics speak for themselves. That cheap Walmart primer covers pretty well, doesn't it?

 

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I've always thought this was a myth. But I did something to cause it recently. When I painted the tub for my 1/24th Monogram 1953 Belair, I gave it a Tamiya base primer coat first. Then I sprayed Duplicolor gold. Only then did I realize that I did a shoddy job of cleaning up the deck. I went back and sanded it smooth, shot more primer then when dry, more Duplicolor. No matter what I did, the red now showed through. It didn't at first, but after sanding I couldn't NOT see it.

So I said "Flock it".

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Aw man, now you've gone and done it. Blew a huge hole through everyone's favorite model building myth.

What's next? You gonna tell us that decals and foil don't need to be "sealed" under clear?

;)

I always spray a clear overcoat over foil. I found that it keeps food fresher and prevents freezer burn.

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I always spray a clear overcoat over foil. I found that it keeps food fresher and prevents freezer burn.

I spray transparent blue over buffed-out metalizer and it looks like blue foil

 

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WRONG! There is such a thing as "red bleed". This is it:

body-with-orange.jpg

You can see clearly the "orange" tint along the creases in the left side of the body, above the rear wheel arch flare and below the fuel filler, at the front right of the roof and at the left side of the hood.

IPA taking the clear coat and paint off. You can see on the real left door that the white primer has no red showing through in the crease, where yu can clearly see the orange tint.

The greeny yellow stuff is the sealer.

I hade the same thing happen with an Italeri Ferrari 275 GTB.

It's not "too thin paint", it's the clear coat leaching dye from the red body plastic. You may choose to believe that it doesn't happen, but it happened o me...

bestest,

M.

Edited by Matt Bacon
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I didn't say your paint was too thin, I said it wasn't opaque enough.

If you think some paint or clearcoat can suck the color out of plastic, get the MSDS for that paint and find out what's the active ingredients. I'll get some of that  and soak some plastic in it and we'll see if any color comes out. I'm betting NOT (unless of course the chemical simply dissolves the plastic, which is another issue altogether).

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BTW, I'm the only modeler I know who's ever experienced so-called "bleed through" with light blue plastic. :blink:

I was painting a model airplane white that was molded in a very light blue plastic. I was airbrushing Model Master Classic White, a paint that's always given me excellent results and coverage, but after five or six coats, that airplane was still a little bluer than Ohio George Montgomery's Willys. I finally gave up and shot it in Floquil Reefer White (flat), which killed all the blue with ONE easy coat. One more coat of MM Classic White on top of that brought me to exactly where I wanted to be.

The MM Classic White simply wasn't opaque enough to get the job done. The Floquil Reefer White was. B)

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You're just not looking at the pictures I posted. Explain to me in any way how "not opaque enough" would account for the gathering of the red tint in the creases and on the ledges of the body, when you can see clearly in the picture in the IPA that the white primer underneath in those places is covering completely.

IPA on its own will leach the colour from Italeri red plastic eventually, as I discovered whilst soaking the 275 GTB, which had to go for weeks because the paint and clear was throughly cured, not freshly applied. The liquid was red tinted, not the yellow of the paint, which came of in lumps, eventually...

best,

M.

Edited by Matt Bacon
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I've stripped paint from parts molded in red, said parts ending up pink or a very washed-out red.  Something is coming out of the plastic in those cases.  That's not to say that red plastic cannot be sealed effectively, though.

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I've stripped paint from parts molded in red, said parts ending up pink or a very washed-out red.  Something is coming out of the plastic in those cases.  That's not to say that red plastic cannot be sealed effectively, though.

Got any pics of these pink or "washed out red" parts? Would be interesting.

I've stripped colored bodies and had them at first glance seem lighter, but it turned out it was either some kind of residue or a slight matting of the surface. Hitting the plastic with a polishing compound quickly and easily brought the color right back.

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Wow. Talk about a thread I wasn`t expecting to see today. :D I was looking for the LOL or something...

Maybe I am misunderstanding, but I always took red bleed-through to be a real thing. Many of you know how many of the 1/12 `67 Corvette kits I have built (molded in red), and have had countless blue or white stripes ending up being pink or purple after clear coat. I have tried high build primers, sealers, even black or blue after primer to try to stop this to no avail. I was finally able to get it to stop by using several coats of silver after primer. I talked about this a little in the "Big Scale Beauty" issue.

Unless I am misunderstanding, or someone has found a cure in the Walmart primers? 

Below is the back of a hood from one of the vette`s. Several coats of Duplicolor primer/sealer, followed by 4-5 coats of Duplicolor white (not sure of the exact code). I then tape of all but the top edge and sprayed Rustoleum clear. As you can see, compared to the surrounding cardboard surface that I used for mounting which has remained white, the white has turned a pinkish color on the actual plastic part. You can also see that the cardboard was previously red! And you can see where the clear has been sprayed, the color is even darker pink:

redbleed_zpsnumthrhu.jpg

 

But maybe I am completely misunderstanding this thread. Help me understand guys.

 

 

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All I can tell you is that I TRIED to get some red bleed on the red interior tub above, fully expecting it in fact, and it didn't happen. And I shot that piece several months ago, so no red has worked its way to the surface in that time. It's still about as white as white can get.

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I painted a lindberg caravan several years ago.using  a mopar brand spray touch up pearl white

I dont remember the  primer brand.

But nothing i did kept it from being pink once dry

Edited by gtx6970
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I painted a lindberg caravan several years ago.using  a mopar brand spray touch up pearl white

I dont remember the  primer brand.

But nothing i did kept it from being pink once dry

Bingo!  I just took a look at the board while eating lunch.  It's obvious Richard is aiming this one at me and the issues I had with my Lindberg Dodge Caravan.  His unscientific example of a single item, and then calling it all inclusive for all red models doesn't fly with me.  Different models from different eras use different plastics and dyes, and will behave differently.

I have a 1982 Cavalier that I painted with Duplicolor primer and then a Duplicolor two tone over that bright red plastic.  Guess what?  No problem at all.  So the 1980s era MPC plastic passed the test.  I have an old Monogram classic model parts car that someone painted white over the burgundy color plastic.  This one is uniformly bright pink. Not a matter of coverage or opaqueness, but red dye making it's way to the surface.

And my own Lindberg Caravan... these were molded in a promo-like plastic to make them shiny right out of the box.  Different plastic and dye, different result.  Yes, the red somehow made it to the surface... through ample coats of Duplicolor primer, several color coats of Duplicolor light blue and that was all fine until I added Testors Wet Look clear.  Bam! The color of blue changed shades... and only where the Wet Look clear had contact with the paint.  There are several areas with decals that didn't change color.

I also have a Caravan.. same red plastic, that I used the same Duplicolor gray primer and a Duplicolor bright yellow for my taxi. with no bleed through issues.  In redoing my blue Caravan I opted for Duplicolor gray primer, then I was adding a coat of silver as a blocker, under the final blue coat.   Then I rather liked how the silver looked so I kept it rather than adding the blue. And I didn't chance clear coating this one.

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Assuming that EVERY red styrene formulation is identical and that they will all bleed or not bleed equally is probably a bad idea, as are most assumptions.

Until every red styrene has been tested with identical prep and coating materials under controlled and repeatable conditions, there is simply NO BASIS to make a blanket statement either way.

 

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This is what I think is happening in the case of the two I've experienced:

 Both were painted the same way -- Tamiya white fine surface primer, then the Zero Paints 2K system. The primer, being a primer, is designed to provide a "key" for paint layers above, and the base coat paint goes one quite rough, and matt, again by design, to give a base for the clear coat that allows it to spread and level without running. I think that means that both the primer and the basecoat are, at the microscopic level, porous. I think that the thinner in the 2K clearcoat mix "soaks into" the basecoat and primer layer. If you've ever done "chromatography" in science, you'll have put a drop of ink onto a solvent soaked piece of filter paper, and watched capillary action separate the ink into its component colours as it diffuses and spreads across the paper. I think that the same is happening here -- the red dye from the plastic is diffusing through the thinner soaked basecoat layer, and into the clear, and then settling with clear as it slumps into the nooks and crannies...

bestest,

M.

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Interesting thread! As someone mentioned in another thread, different builders will experience different things. I can only tell you that I've been wary of red and yellow plastic for a very long time (since the '80's) as I've also had the dreaded "bleed through" problem. The problem might not lie in the color of the plastic, but how "tough" the plastic is. In other words manufacturers can change their quality of plastic from time to time, and that can change how different paints will affect different kits at different times.

Back in '99 I built this '55 T-Bird which was converted from Monogram's '56. Needless to say after I got stung by the "bleeding plastic" a couple times before, I figured that I better use some type of barrier as I absolutely did not want yet another red car, but the T-Bird Blue which as one of the colors for a '55. I simply overcoated the plastic with Future, and no bleed through whatsoever.

tbirdconvtopup

PA127608

DCP 0284

So yeah, in MY experience I have indeed had red and yellow plastic bleed through, and IMO it does occur and sometimes can keep happening no matter what one does to the plastic short of burying it in some sort of sealer. Something I recommend anyway especially if major bodywork has been done. 

 

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Assuming that EVERY red styrene formulation is identical and that they will all bleed or not bleed equally is probably a bad idea, as are most assumptions.

Until every red styrene has been tested with identical prep and coating materials under controlled and repeatable conditions, there is simply NO BASIS to make a blanket statement either way.

 

Hey Bill! Great minds think alike eh?? I was typing the same thing right at the same time you were posting. :D 

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It's obvious Richard is aiming this one at me and the issues I had with my Lindberg Dodge Caravan.  

Not so, Tom, and I apologize if you took it that way. I didn't even remember who it was or what model that inspired me to run my little test some months back. Many, many here have discussed this issue many, many times.

In the cases where this problem doesn't surface (no pun intended) till clear-coat time, I think it's possible that the clearcoat is breaking down the color coat in some kind of way that lets the red plastic show through more readily. I'm still not convinced that any dye or pigment is actually coming out of the plastic itself and working its way up through the paint.

I'm looking for a chemical or solvent that I can put on a white rag, rub on colored plastic, and have the rag turn the color while the color in the plastic is lightened. THAT would prove that something is "leaching" the color out of the plastic. Oh, lacquer thinner, acetone, MEK, etc will get plastic color on the rag but that's because they're actually dissolving the plastic itself. (And the crazed plastic on the body will still be the same color, no lightening.)

Has anyone considered the possibility that chemical reaction of some kind is actually creating the red tint? I ask because I've stripped white paint off white plastic using a white chemical (Easy-Off) and had some of the removed residue be a yellowish or tannish shade. Where's THAT coming from? While stripping with Easy-Off, I've also seen weird colors appear that had nothing to do with any paint on the body, or the plastic underneath. I can't give you a specific example, but I know I've seen this several times.

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That's dye chemistry. The chemical in the stripper is (probably) oxidising something in the paint. Same reason white paint can yellow with age (not just absorbing horribles from the air...) 

And does it matter if the red is a separate _pigment_ coming through the base coat, or "molten" plastic? It's still red stuff surfacing in the clear coat.

BTW, polystyrene is inherently transparent. As you'll have noticed when cutting clear parts off the trees, it's also rather brittle. To make it more tractable, it is "filled" with inert material (like talc), and coloured with dyes.

I'm doing a little experiment...

best,

M.

Edited by Matt Bacon
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Guys, DupliColor makes an Engine enamel Primer that has ceramic in it. I use it all the time, it goes on thin, sands smooth, and stands up to the lacquer paints.

I bet with the ceramic in it, it would make for a good barrier over colored plastics..... what do you guys think?

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