Yellow (UGH!) plastic cover-up.

[Hi-Po]

Thanks everyone for the great advise and suggestions, it is appreciated.  After much thought and consideration, I have decided that I will go ahead and prime the body with Tamiya  gray primer.  Then I will either spray a couple of light coats of Tamiya white primer (to help the color coats to stay bright)  or I will go ahead and spray the color coats.  Hopefully, the Silver Jade is dark enough (over the gray primer) that the yellow will not bleed through.  However it turns out, it will be a learning experience and that is what this hobby is about.  You win some, you lose some.

 

[Can-Con]

Here's a good example of what the BIN can do.

JoHan mustard yellow ,,

Custom work done and a few coats of BIN,,,

 

Painted in January 2017 and this pic was taken this time two years ago. Worked on it a bit last night, still looks the same as when it was painted, no bleed , no wrinkling, cracking or anything else.

Edited December 28, 2019 by Can-Con

[Snake45]

Long story short, I think you're over-worried about yellow "bleeding through" your Silver Jade. Over 20 years ago I painted a yellow '69 GT500 with one thin coat of light grey primer and a couple airbrushed coats of Grabber Green--which is lighter than your color--and I had NO "bleed through" at all. None. Simply not a problem. 

Now, if you were painting it white, or silver, or a light blue or gray, you might want to worry. 

[Brutalform]

This stuff works every time. 
Never tried it on yellow, but works great on red. 

[JollySipper]

2 hours ago, Brutalform said:

This stuff works every time.

Where could one get that? and would you recommend it if you were going to paint the model with a different red? I have one molded in red that I would like to paint a deeper darker shade....

[vamach1]

On 12/26/2019 at 8:36 AM, TarheelRick said:

This is an example of bleed through.  If you look just below the word "Service" on the cab you can see a slight color shift in the white, then if you look really closely just under the sleeper window you can see a color shift in the gold.  This cab was molded in red, that strip around the cab is white styrene.  I used every tip that has been mentioned, except for the Zinsser primer, and I still got bleed through.  However the Mustang was molded in yellow and I had no problems with bleed-through and it was painted the same way using the same colors.  I really think bleed through is some form of demonic force that enjoys playing tricks on unsuspecting modelers.

Nice truck and Mustang.

[LL3 Model Worx]

A couple coats of Duplicor (clear) adhesion promoter (allow to fully dry) and follow with some primer... should do the trick.

So I would imagine.

 

[Brutalform]

5 hours ago, JollySipper said:

Where could one get that? and would you recommend it if you were going to paint the model with a different red? I have one molded in red that I would like to paint a deeper darker shade....

I bought it on Amazon for about $8. I’m sure it’s available in many craft stores also. 
After priming a red body, and the red starts showing through the primer, I hit it with two coats of this, and no problems. 
I don’t see any problems if you were going from a red to a darker red. You might have a problem going to a lighter shade of red though. You’ll have to give it a try to see. I usually test my paints on an old body or some other part I probably won’t ever use. 

[Bucky]

Here's what I started with:

AMT '62 Impala convertible body with MONOGRAM '58 Thunderbird roof.

Here's the final:

I applied about four coats of Duplicolor sandable primer, then about four coats of

Duplicolor gold. I can detect a slight red tint to the gold on the roof. It doesn't bother

me too much, since it's on the roof. If it had been the hood, or a fender, or patch

panel somewhere on the body, it would have been problematic. This is the sort of

"bleed thru" I would like to avoid in future builds.

[Flat32]

Did a little research and found that color dye, as opposed to inorganic pigment, is commonly used for coloring styrene and there is such a thing as solvent soluble powder forms of dye.  I suspect this bleeding is maybe the paint solvent actually leaching the dye out of the plastic.  I have no idea which paint solvents could leach the dye, could be all or only some. if this is the case.

At any rate a simple test could be done on a sample of whatever colored plastic is in question.  Take a bit of sprue wrapped in white paper that is wetted with whatever solvent is in your paint and put it in a zip bag to keep the solvent wet longer.  Maybe a couple hours later unwrap and if the paper shows signs of color you've located the problem.  Trick would be to test other solvents to see if there's one that won't leach the color. Most likely alcohol, the stuff that thins the Bin, will leach the least if at all.  Just guessing here.

Would make sense to paint first coat with a paint that uses a solvent that doesn't leach the dye.as a barrier coat. Would make sense also to have as much of the sanding done as possible so the barrier isn't compromised when sanding subsequent coats of normal primer.

[Snake45]

5 hours ago, Flat32 said:

Did a little research and found that color dye, as opposed to inorganic pigment, is commonly used for coloring styrene and there is such a thing as solvent soluble powder forms of dye.  I suspect this bleeding is maybe the paint solvent actually leaching the dye out of the plastic.  I have no idea which paint solvents could leach the dye, could be all or only some. if this is the case.

At any rate a simple test could be done on a sample of whatever colored plastic is in question.  Take a bit of sprue wrapped in white paper that is wetted with whatever solvent is in your paint and put it in a zip bag to keep the solvent wet longer.  Maybe a couple hours later unwrap and if the paper shows signs of color you've located the problem.  Trick would be to test other solvents to see if there's one that won't leach the color. Most likely alcohol, the stuff that thins the Bin, will leach the least if at all.  Just guessing here.

Would make sense to paint first coat with a paint that uses a solvent that doesn't leach the dye.as a barrier coat. Would make sense also to have as much of the sanding done as possible so the barrier isn't compromised when sanding subsequent coats of normal primer.

For years, when this debate comes up, I've been asking for someone to name me the solvent or chemical that will take the color, any amount of it, out of styrene plastic without dissolving or damaging the plastic itself. So far, no one has been able to do it. And I doubt we'll get an answer this time either. 

I've also asked for someone to show me a body that's been painted and stripped and the color seems to be faded out of it, even a little. No one's been able to do that, either. 

I don't believe it's a matter of any color coming out of the plastic and into the paint. I think this is just a matter of particular paints not being opaque enough to cover the colored plastic. And I think that something about the wavelength of light up in the red-orange-yellow end of the spectrum in some way is able to penetrate coatings better than wavelengths down in the green-blue-violet end. Isn't it odd you never hear anyone complaining about having blue or green or black plastic "bleed through"? 

[Dave G.]

4 hours ago, Snake45 said:

For years, when this debate comes up, I've been asking for someone to name me the solvent or chemical that will take the color, any amount of it, out of styrene plastic without dissolving or damaging the plastic itself. So far, no one has been able to do it. And I doubt we'll get an answer this time either. 

I've also asked for someone to show me a body that's been painted and stripped and the color seems to be faded out of it, even a little. No one's been able to do that, either. 

I don't believe it's a matter of any color coming out of the plastic and into the paint. I think this is just a matter of particular paints not being opaque enough to cover the colored plastic. And I think that something about the wavelength of light up in the red-orange-yellow end of the spectrum in some way is able to penetrate coatings better than wavelengths down in the green-blue-violet end. Isn't it odd you never hear anyone complaining about having blue or green or black plastic "bleed through"? 

I know yellow will backlight awesome and shine right through light primer but not dark stynylrez. It's like a shade on a lamp effect, kind of a diffused light. Priming inside and out may help if your theory is correct. And I'm not here to say you're right or wrong !

Edited December 29, 2019 by Dave G.

[Flat32]

The simple test I suggested is only aimed at determining if the color migrates or not in only the one case at hand. If it doesn't migrate then lack of coverage opacity would be a more probable cause of the problem.  Could even be both happening.  The technical articles I'm finding mention color dyes being more prone to migration than pigments and there are many different dyes with different characteristics. You would be surprised how uncontrolled the coloring of plastic was only thirty years ago.  I spent twenty years in Taiwan getting plastic parts tooled and produced by small and medium sized molding shops.  You get to see how many ways there are to screw up and who takes the blame.

My wife may still have her red sweatshirt.  I threw away my pink underwear.

[Belugawrx]

This is the replacement hood I tried to match to white plastic body in last years Cannonball

I started with Duplicolor Primer Sealer Grey

The scoop came from a 67 corvette and is also molded in white...

Then I sprayed Duplicolor Silver as a further barrier, from a tip I read on a forum somewhere..

There was a slight blush around the edges, but I thought the colour coat would cover...

Nope..

So I painted it something totally different...

Then I hit with clear, and the red came back again,..even worse, ...so black it is now...

So you can't really say it doesn't happen

 

 

 

 

Edited December 29, 2019 by Belugawrx

[Flat32]

This is the best resource I've found for technical information on this subject.

https://books.google.com/books?id=Q4X1ovFVBvoC&lpg=RA1-PA34&ots=onnbtk1uSo&dq=red color dye migration in plastics&pg=RA1-PA31#v=onepage&q=red color dye migration in plastics&f=false