Removing HOK candy paint and troubles related to that

[DustyMojave]

My son recently painted an AMT Fast & Furious Supra with Testors Metallic Silver rattle can for undercoat and top coated it with House of Kolors Kandy Cobalt Blue. He got some runs in the blue, so he decided to strip it. I provided Super Clean (post-Castrol stuff, but still in the purple jug, labelled "BioDegradable"). It softened some of the paint, but severely attacked the plastic. The body is destroyed beyond recovery unless he wants to build a crash & burn diorama. Here are some pics of the body.

A couple of weeks ago I had used the same stuff to try to remove chrome from the engine of a 10-year old AMT 57 T-Birdand it took days to remove the chrome, but left the yellowish lacquer and didn't touch the styrene. I also used "Purple Power" degreaser and "LA's Totally Awesome" on that with no better luck. However none of them attacked the plastic.

I'm thinking maybe the gray AMT styrene which is so soft to the touch, is vulnerable to the current formula of Super Clean. The T-Bird was molded in white styrene which is the harder stuff similar to what was used back in the 60s and 70s.

I'm not a total dummy about such things, I spent 11 years in plastics R&D, 6 of that in a test lab. But I'm hoping someone has some recent experience.

My friend has a chassis for a recent issue AMT 69 Barracuda molded with the gray styrene he wants to strip paint off of now and we're afraid to use the purple stuff again. I did a search of this site for removing paint before posting this. Anybody have any up-to-date suggestions on removing paint now with what is currently available? With kits retailing at $25-28 these days, such problems get expensive REAL quick.

[Guest G Holding]

Gramps taught me, I and others do this simple mix....Acetone and water. YES Acetone...if diluted with 20 % water will dissolve the paint without attacking the plastic.

Use some sprues from the kit you want to strip, mix a 80/20 mix and drop your sprue in it.....wait and watch...if any problems add a bit more water. I do this in a 3# coffee can and was done down to bare plastic in 30 minutes, less if you use a short bristle brush

had pictures, but can't locate now

Edited April 5, 2013 by G Holding

[Longbox55]

I don't beleive the problem is the Superclean, but rather the use of HOK paint on styrene without proper prep. Real HOK is very hot, and will craze plastic in the same manner as the body in your pic. I've stripped plenty of kits in Superclean, new and vintage, and have never seen that issue.

[DustyMojave]

Note that there was NO damage to the plastic for the several weeks before it went into the Super Clean. ALL of the damage happened in the Super Clean. So IF the HOK paint caused this damage, it would HAVE to be that the HOK reacted with the Super Clean.

[Longbox55]

A reaction between the HOK and the Suerclean could very well be the issue. It's making me wonder if perhaps there wasn't still some solvents from the HOK trapped between it and the Testors Silver that was used as the base. If the base was enamel, the Superclean would have dissolved it first, possibly exposing the plastic to any residual solvents. The damage itself definatly looks to be the kind of solvent crazing one would get from a hot laquer paint or thinner.

[DustyMojave]

So on a slight diversion, Longbox55, what do YOU suggest as "proper prep"? The directions on the HOK can are DEAD simple and essentially the same as Testors, Plastikote and Pactra and all the others have always been.

"1. Apply base as directed. 2. Allow thirty minutes dry time before applying KANDY KOLOR KOAT."

On the Testors can:

To avoid possible wrinkling, recoat within 3 hours or after 48 hours. When using transparent colors, first spray undercoat of silver, gold or metallic copper. Spray in light mist coats to achieve desired depth of color."

No other directions are supplied regarding prep by either manufacturer. Only instructions on shaking the can and how far away to spray from and temperature/humidity requirements with ventilation remarks.

And NO, I'm NOT going to try acetone anywhere near styrene or throwing lit matches at my gas filler neck.

Note that the color coat is "House of Kolor Kustom Kolor Kandy Color Coat Kandy Cobalt Blue" by Valspar in a rattle can purchased from the hobby department of a department store. This was NOT from a custom mixed can of paint from an automotive paint supplier. The base coat, again, was Testors rattle can 1246 silver. I've not seen any other possible compatibility issues from putting HOK spray paint in contact with Testors paint.

[DustyMojave]

"The damage itself definatly looks to be the kind of solvent crazing one would get from a hot laquer paint or thinner."

Like dropping it into a tub of acetone and water...

Not wanting to be mean to GHolding, I just have strong doubts about that and don't want to try it.

The styrene was definitely rubbery and the blue paint relatively "crusty" over it as though the HOK was not much affected by the Super Clean. Note the increased effect on the styrene around door lines and such.

[Longbox55]

So on a slight diversion, Longbox55, what do YOU suggest as "proper prep"? The directions on the HOK can are DEAD simple and essentially the same as Testors, Plastikote and Pactra and all the others have always been.

Note that the color coat is "House of Kolor Kustom Kolor Kandy Color Coat Kandy Cobalt Blue" by Valspar in a rattle can purchased from the hobby department of a department store. This was NOT from a custom mixed can of paint from an automotive paint supplier. The base coat, again, was Testors rattle can 1246 silver. I've not seen any other possible compatibility issues from putting HOK spray paint in contact with Testors paint.

Bit of a 2 parter here. On te prep part of things, sealing the plastic is necessary when using hot paints, especially most automotive grade laquers. A quality primer is the best, though some use Future or BIN as a sealer. I personally use Duplicolor primer, but I rarly use any of the hotter automotive paints, mostly Duplicolor Perfect match or the occasional PPG paint.

Now for the second part. When you mentioned HOK in the first post, I took it you meant actual 1:1 HOK, which is a rather hot paint. The Kustom Kolor (which I also use) is a completely different animal, being a modified urethane, rather than a laquer. I have had to strip it myself in the past, Superclean will not touch it. I didn't have the reaction issues like what you've shown, though. It was merely difficult to remove. The kit in my case was a Revell '57 Chevy (new tool) and had a Duplicolor black primer/Testors laquer as the base.

This seems very odd to me that there would be a reaction, as I've never seen Superclean do anything like this before. I wouldn't think the Testors/Kustom Kolor combination would cause this. Perhaps a bad batch of Superclean?

I do agree with you about the acetone. Been there, done that, ruined a Revell '56 F-100 body with it.

[Casey]

Interesting. It looks like a Revell '67 GTX body I left sit in PinSol overnight as a test. The plastic turned soft and the edges were curled inward, though not as extreme as the RF on your Supra body.

Richard, do you have any unpainted parts remaining from the same Supra kit you can drop in the SuperClean as a control test?

[935k3]

Try 91% alcohol nex time. i have learned a basic rule of stripping paint safely, if it's lacquer use 91% alcohol. If it's enamel use Easy Off(yellow can) or Purple Power. HOK is lacquer. I also use Easy off to strip chrome, it takes about 10 minutes.

[Brett Barrow]

AMT was using some strange plastic during that era. Revell also had some weird plastic issues around that time as well. The story inside the industry was that it was due to the construction of the Chinese F1 race track which used up the entire Asian polystyrene supply at the time. I'd chalk this one up to plastic weirdness. I had the same thing happen to an AccMin Grand Sport I tried to strip in Super Clean. First and only time I ever used it. I poured the rest down the drain.

Edited April 7, 2013 by Brett Barrow

[Guest G Holding]

"The damage itself definatly looks to be the kind of solvent crazing one would get from a hot laquer paint or thinner."

Like dropping it into a tub of acetone and water...

Not wanting to be mean to GHolding, I just have strong doubts about that and don't want to try it.

The styrene was definitely rubbery and the blue paint relatively "crusty" over it as though the HOK was not much affected by the Super Clean. Note the increased effect on the styrene around door lines and such.

Not hurtin me at all. Most people say the same thing as did I....Bill told me, he's been doing this for a while.

So do as I told you...try it with some sprue...any and all. The 20% water makes it happen.

OH if you think acetone will hurt plastic...check your lacquer or enamel labels...you might see some things you don't want on plastic right on the can.

I have stripped more HOK than I can remember, This is the real safe trick.

PLEASE DO NOT USE ACETONE......BUT WHY NOT ?.......

As for the original problem...that car is bad....I suspect the enamel was not dry,and was still hot, when the HOK was removed I think the reaction was held under the lacquer as it was dry. I have used everything to strip from lye to 91% alcholhal and the Acetone is the safest and quickest...both resin and styrene

I assume that real HOK was used, not Kustom Kolors...

Edited April 7, 2013 by G Holding

[CadillacPat]

House Of Kolor paint is NOT Lacquer.

HOK is Urethane Enamel.

I use House Of Kolor paints on all kinds of plastic and while it may craze hard plastics that are not properly primered like Styrene, it will not melt and warp a body like the one you've shown.

Kustom Kolor, is not House Of Kolor paint, only their pigments in a special forumlation designed for good adhesion to plastic.

Kustom Kolor is also not a Lacquer.

CadillacPat

[DustyMojave]

Thanks CadillacPat and you other guys. I think I caused some confusion over the House Of Kolor paint. As I said in post 7, it was NOT the hot automotive lacquer. It WAS the rattle can KustomKolor paint for models.

BrettBarrow, what paint had you used on that AM GS Vette? (I note your avatar is the trademark of Lockheed Aircraft's Skunk Works, I drive past there and the Blackbird Airpark Museum a couple times a day 5 days a week...so I suppose you're into aircraft as well as cars)

And which version of Super Clean were you using?

[Brett Barrow]

Thanks CadillacPat and you other guys. I think I caused some confusion over the House Of Kolor paint. As I said in post 7, it was NOT the hot automotive lacquer. It WAS the rattle can KustomKolor paint for models.

BrettBarrow, what paint had you used on that AM GS Vette? (I note your avatar is the trademark of Lockheed Aircraft's Skunk Works, I drive past there and the Blackbird Airpark Museum a couple times a day 5 days a week...so I suppose you're into aircraft as well as cars)

And which version of Super Clean were you using?

Funny that I changed my avatar before i read your post! Yeah I dig airplanes, too. I used it for a long time. My dad called me "stinky" when I was a kid.

The paint I used was Testors Nassau Blue from the lacquer line. The Super Clean was from back when it was still Castrol brand.

Edited April 11, 2013 by Brett Barrow

[DustyMojave]

Bizarre coincidence on the avatar there! Skunkworks was doing flight testing of an F35 yesterday and when the pilot would pour on the power right over where I was working, it made an odd loud howling noise which I would NOT exactly term "stealthy". We get to see all sorts of exotic aircraft here as Skunkworks is located in an AirForce manufacturing site where most of the exotic American aircraft are developed. It's called "Plant 42. All the major military aircraft companies are there and all of the stealth fighters and and bombers have been developed there: F117s, F22s, F35s, B1s, B2s; and the Space Shuttles were all built and serviced there too.

So back to the subject matter for this thread...

It appears we may have cause for a cautionary note here. 2 models from different manufacturers, using different paints (1 Lacquer, 1 urethane) and using Super Clean (1 Castrol, 1 non-Castrol), have been destroyed in trying to strip them

Perhaps we should recommend using Super Clean and similar strong detergent solutions only to remove paint known to be conventional enamel .