Jump to content
Model Cars Magazine Forum

what did i do wrong red molding painting it white


Recommended Posts

im not sure what i did wrong, i got the amt 72 chevy pickup coke kit, which is molded in red.

 

i wanted to paint it white, so i primed it gray using tamiya primer. then i did a coat of tamiya silver, and then a tamiya white primer. everything looked fine.

howver when i did my white paint, everything turned pink.

 

i really wanted this white and short of just buying the mpc version that is molded in white, im not sure what to do

Edited by youpey
Link to comment
Share on other sites

There's a recent thread on this. My contribution was that I read a paint technology book that said that the typical red dyes in plastic are easily dissolved by paint thinners. and then move to the paint surface. I would use a water-based acrylic as primer, and then be very careful with the next layer(s) that contain solvents.

Rob

Link to comment
Share on other sites

I've been using this stuff for about 30 years. [geesh, now I feel old 🤨] works for me.

prime first with whatever you usually use. BIN won't stick to bare plastic unless it's primed or completely sanded. Easier to just prime.

I comes out of the can like a fire hose so better to decant it and spray with an airbrush. I just use regular rubbing alcohol to thin it and for cleanup.

Also blocks hot lacquers. You can spray heavy wet coats of auto lacquer or HOK over it without damaging the plastic.

steve's pics 073

Link to comment
Share on other sites

20 minutes ago, robdebie said:

There's a recent thread on this. My contribution was that I read a paint technology book that said that the typical red dyes in plastic are easily dissolved by paint thinners. and then move to the paint surface. I would use a water-based acrylic as primer, and then be very careful with the next layer(s) that contain solvents.

Rob

This is basically right. I'd use Stynylrez primer which is an acrylic poly resin primer/sealer. Or the Zinsser mentioned already. If you use a platinum silver paint over that you should see if the red came through or not, to which it shouldn't in either case. Then be good to go with white.

Edited by Dave G.
Link to comment
Share on other sites

If you spray the paint a bit too wet, it can reactivate the paint/primer below causing this issue. Zinsser bin works great through an airbrush but terrible from the can. It works well because it is shellac based so not so affected by lacquer thinners inside the base coat/ clear coat.

Edited by Michael jones
Link to comment
Share on other sites

1 minute ago, yh70 said:

why did you use a silver primer over a grey ? ...that was a big waste and a mastake... u should have just primed with some flat white, then sprayed your gloss white on. then u would been all good..

Some modelers think that the metallic particles in silver paint prevent the red or yellow dye from bleeding through.   I guess you haven't heard of that.

Are you saying that just using plain flat white paint (what brand?) undercoat will prevent dye bleed-through that primers and silver paint can't prevent?

Link to comment
Share on other sites

19 hours ago, peteski said:

Some modelers think that the metallic particles in silver paint prevent the red or yellow dye from bleeding through.   I guess you haven't heard of that.

Are you saying that just using plain flat white paint (what brand?) undercoat will prevent dye bleed-through that primers and silver paint can't prevent?

nope never heard that before..i used Walmart brand for many years till they quit making it ... now i will use Rust-Oleum 2X Ultra Cover Flat White Primer...white paint has always been hard to paint over a dark surface anyway... another thing i have learned (and i picked this up from aircraft builders) is prime white then paint with a flat white then clear coat..a gloss white is so hard to spray , but a flat white with a clear over the top is not.. 

Link to comment
Share on other sites

19 hours ago, peteski said:

Some modelers think that the metallic particles in silver paint prevent the red or yellow dye from bleeding through.   I guess you haven't heard of that.

Are you saying that just using plain flat white paint (what brand?) undercoat will prevent dye bleed-through that primers and silver paint can't prevent?

Peter, I've seen this conversation played out over many model boards for as long as I've had a computer.

There's some people who you just can't make believe red plastic will sometime have dye in it that will bleed out into the paint you put on it. They think for some reason that it's just a matter of the paint being transparent or something and it's just the painter not getting coverage. 

You'll never convince them that the plastic is actually changing the color of the paint. 

I've given up trying to convince anyone. I just let them know what has worked for me. What they do with the knowledge is up to them.

Link to comment
Share on other sites

On 11/24/2021 at 6:49 PM, youpey said:

i guess if i can find the white mpc kit at hobby lobby during 40% off time i will get it, otherwise im just going to move on because it wasnt a very well detailed kit, and i already spent enough 


I have been there and I just bought another kit molded in grey or white. Coke or not  Round2 knows we prefer kit molded in white or grey…

Link to comment
Share on other sites

I for one don't think plastic dye leeches out into the paint. From my observations it is simply that if you use all lacquer primer and paint over red plastic, you can reactivate the paint below causing the red to show. This can even happen when applying the clear coat (and even 2k!) I have seen this on other coloured plastic before as well - not just red! That is why bin zinsser is very effective at stopping this happening.

Edited by Michael jones
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...