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Paint Question for you guys

White turned bone color

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#1 JustBill

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Posted 28 December 2011 - 07:45 PM

I've never had this happen as suddenly as this did. I painted a car white using Dupli-Color. Then after it dried for weeks, I cleared it with a few light coats of dupli-color. Looked great but had some orange peel. After letting it sit for weeks I smoothed the orange peel out with 3200grit and cleared it again. After sitting in the dehydrator for 8hrs. or so it has yellowed. That's what I believe it has done. It turned to a bone color. I've seen white do this over time but never with in 8hrs. Any thoughts on how to possibly fix this or what I did to cause it from happening again? I've already tried buffing it. I would post pics but the yellowing doesn't show in pics.

#2 Erik Smith

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Posted 28 December 2011 - 09:32 PM

What color is the plastic? Duplicolor is hot and the clear will bring plastic color through layers of sealer, primer, and paint. I don't think it would be similar to the aging of enamels which will yellow over time. This sounds more like some chemical reaction or reaction to the plastic.

#3 CadillacPat

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Posted 29 December 2011 - 12:41 AM

More info is needed here.

Did you prime and with what?
DupliColor is a Lacquer and only requires an hour to dry.
If you wait a long time after laying down your basecoat you need to come back and scuff it or apply an Intercoat Clear for the next layer to have adhesion.

The Clear you applied after sanding probably bled through to the plastic and caused discoloration.

Solvent paints can chemically react with hard plastics (especially styrene) to produce a grainy orange peel effect.

If you can list your steps it will be easier to tell what happened.

CadillacPat

#4 JustBill

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Posted 29 December 2011 - 04:55 AM

The plastic is white. I primed it with dupli-color white sandable primer. Then cleared it with dupli-color acrylic enamel clear. its a two tone paint scheme and the other color I used was a flat hot pink so I kept the white flat as well and just cleared them. Here is a pic of the car but like I said, it doesn't show the bone color.
Posted ImagePosted Image

#5 JustBill

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Posted 29 December 2011 - 05:08 AM

It could be that the clear didn't like the dehydrator? Or did it have a reaction with the white primer and pull out pigment?
Here are my steps, I primed the whole car with DC primer, Put it in the dehydrator. Taped off and painted the pink, put it in the dehydrator. Put down a few light mist coats of clear, put it in the dehydrator. Sanded the body down with 3200grit. Cleared a light coat then a heavy coat. Put it in the dehydrator. It wasn't till the last time I put it in the dehydrator that it turned colors on me. Hope this helps you guys. At this point I'm assuming that it just needs stripped? It wouldn't suprise me as this is the second time I've painted this car so this will be the second time I've had to strip it. This car has had a curse on it since I pulled it out of the box. <_<

#6 heatride

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Posted 29 December 2011 - 07:16 AM

Bill this is post that has nothing to do with your (paint problem) . If that is a bad paint job I want to see
a good one ! :) Looks purdy ..........

#7 JustBill

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Posted 29 December 2011 - 07:40 AM

HAHA! Thanks for the complement man! Believe me, if it looked as good in person as it does in these pics I would be beside myself.
I went outside and took some pics in the daylight and the pic still not showing the bone effect that's going on. Its not a terrible looking color and its a uniform effect going though out the white. I'd leave it like that if I didn't think I would get poked with sticks and be made fun of for it not being accurate! :D

Edited by JustBill, 29 December 2011 - 07:45 AM.


#8 A.R.C.

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Posted 29 December 2011 - 08:06 AM

How old was your Dupli-color clear? I`ve had the same problem with yellowing and it was from the old can of Dupli clear that I used. The can I used was a couple years old and hardly used but it managed to yellow so bad it made my metallic charcoal take on a slight gold looking tinge. I sprayed the clear on the side of my white boat to see how yellow it was and it was terrible. It was the color of Shellac.
I had other cans of the same brand clear that were just as old and tried those and they were fine, just a bad can I guess, but since then I always do a test spray(even with new cans) just to make sure all is good.

#9 scalenut

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Posted 29 December 2011 - 08:06 AM

hey Bill ,
If I recall .. Duplicolor offers enamels and Lacquers in paints and I believe the Duplicolor white (sandable) primer is Lacquer... (the one i use is)
Is it possible you had a miss match in paint types? just a shot in the dark because it's not very clear on the different cans ..what is what

Edited by scalenut, 29 December 2011 - 08:08 AM.


#10 ffreak

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Posted 29 December 2011 - 08:29 AM

From my experience i'm thinking it has something to do with the use of the " enamel clear ". I used to have the same problems very often, after I switched to laquer exclusively, problem solved !!!

Edited by ffreak, 29 December 2011 - 08:31 AM.


#11 JustBill

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Posted 29 December 2011 - 10:34 AM

Yea, I was kinda hoping for the paint fairy to fly in here and wave a wand and say "use this...." and all your problems will go away. I guess someone shot her?!?! :unsure:

#12 jbwelda

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Posted 29 December 2011 - 05:27 PM

at this point i would be soaking the body in paint remover if you really dont want the yellow/bone tint because its gonna need to go back to bare plastic pretty much...

thats a problem i have had with white: just about any (buzz can) clear i have tried has a pretty pronounced yellow tint to it, at least enough to turn the shade from pure white to something else. you might want to try not using a clear on this but i assume you have a line between the two colors you want to bury.

if there is a gloss clear that doesnt have a yellow tint i would like to hear about it...

#13 ffreak

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Posted 29 December 2011 - 06:10 PM

The Tamiya TS13 is what I switched to that solved my problem. After about 5 or 6 years now it still hasn't yellowed.

#14 Monty

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Posted 29 December 2011 - 06:39 PM

if there is a gloss clear that doesnt have a yellow tint i would like to hear about it...


About a year or so ago we had a fairly in-depth discussion about this, and one of our now-former members recommended a product you should be able to find at Hobby Lobby & other crafts stores. He claimed it was a better long-term solution that anything the model hobby industy offered and that it could be sprayed over any type of paint without causing any problems. Unfortunately, when members become former members on here their posts seem to get eradicated, so I no longer have the name of the product.

Harry, any chance you can still dig up Bluesman Mark's response?

#15 tabsscale1

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Posted 29 December 2011 - 07:29 PM

I have never had Duplicolor Clear paint yellow. The 56 chevy in my avatar is still white after 5 or 6 years now.

Edited by tabsscale1, 29 December 2011 - 07:33 PM.


#16 Art Anderson

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Posted 30 December 2011 - 05:19 AM

I think the operative term that crops up here is "enamel". For starters, enamel paints are basically pigmented varnishes, of one sort or another. I've never seen a pure clear varnish in all my life as a model builder. The solids in varnishes I've known are either slightly amber (yellowish) in tone, or they soon turn so upon drying, and aging. To see this, take a look, if or when you can, at the varnished woodwork in older houses--even on white oak, or white pine, that varnish gave a "golden" tone to the raw, unstained wood, and gradually darkened over time to varying shades of brown.

With the coming of white pigments, most generally white lead, cadmium white, barium white, titanium white, color technicians found that those pigments themselves do not yellow with age, or if so, only so slightly that the yellowing is almost imperceptible unless compared to a fresh sample. But, with enamels, with their varnish carriers, will darken over time--I've not seen a truly white enamel, with the possible exception of the white house paint my Dad used to use on the siding of our house back in the 1940's into the early 1960's--the carrier for that type of white paint was linseed oil, thinned with turpentine, and if it yellowed, it was more likely due to pollutants in the air, rather than from exposure to light--that paint chalked out readily, the carrier wore away with rain, wind and sun, exposing more white lead pigment.

Most :"white" automotive colors historically were never really "pure white", that was pretty much reserved for kitchen appliances (think "refrigerator white"), but rather were muted to some degree by adding traces of colored tinting pigments in mixing--this gave the white automotive paint a "warmer" shade, which didn't contrast quite so starkly as if it had been truly pure white. I've been told over the years that it was also thought that adding minute amounts of "tint" to the white used was believed also to slow down the weathering and "chalking" that was a common feature of nitrocellulose lacquer finishes which were used almost universally across the auto industry from the mid-20's until DuPont introduced acrylic lacquers (which are plastic based) on General Motors cars in 1958--the so-called "Magic Mirror" finishes highly touted by GM for almost a decade after '58.

With both nitrocellulose (basically cellulose nitrate, a clear material once used as camera film, dissolved in a blend of acetone, ketones and other strong solvents) and acrylic (synthetic clear plastic based carrier) lacquers, there is little if any yellowing of the carrier over time.

Even with urethanes, there are urethane resins, and there are urethane resins. The finest, and most expensive of these is optically clear, and stays that way almost indefinitely.

The solution to doing a two-tone color such as this, a combination of both white (ground base color) , "Day-Glo" or fluorescent colors (which in themselves are VERY translucent (fluorescent colors are made with dyes rather than pigments), is to use, to the greatest extent possible, clear lacquer as a top coat (most all fluorescent colors give a dull, flat finish, and need to be cleared to not only seal them from dirt and grime, but also to give them a shine. Most readily available fluorescent, or Day-Glo colors tend to be enamel based, but they can be applied over lacquers, and they CAN be cleared with clear lacquer (I've done that many times in the years I concentrated almost exclusively on modeling the cars that ran the Indianapolis 500 Mile Race, which collection included several STP Indy Cars, even other teams who used at least some fluorescent colors as accents or trim.

Paint the model white, mask off what is to remain white, then spray on the fluorescent color, remove the masking tape, and then AIRBRUSH a clear lacquer such as Modelmaster or Tamiya, gently so as to not disturb the fluorescent. That always worked for me, and no, it never yellowed perceptibly, even after the model had been done for several years.

Hope this helps!

Art

#17 JustBill

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Posted 30 December 2011 - 07:14 AM

Art, that does help a ton. And you hit the nail on the head. This is my first time with a enamel base clear. And like you said, the whole reason for using it and not the lacquer that I always use, is so that it wouldn't bother the florescent. I figured the lacquer clear would eat the florescent paint right up. I thank you for your time and explanation sir! Do you have any experience with Testers 1261 gloss coat clear? I know its a cold lacquer and I use it exclusively to clear my decal projects as it won't harm them. Do you think it would bother the florescent? I guess the only way to know for sure is to try it. Thanks again man!