# Rubber Melting Plastic Question



## liskorea317 (Mar 27, 2009)

Hi everyone!
I had a car kit that was released in the 90's and repopped a few years ago. In the 90's the car had plain plastic hubs to which the rubber tires were mounted. It also had plastic axles to attach to the plastic hubs. Not knowing about the problem with rubber and plastic at the time I just built the kit normally. I had stored the finished model away and recently when I found it the rubber had destroyed all the plastic it was in contact with. I had seen that the kit was re released so I got the repop but now the hubs were chromed, and the axles were metal, but the tires were still the same rubber or vinyl. The question I have is should I have to worry about the rubber ruining the chromed parts? I tried covering the part of the hubs that is in actual contact with the rubber with bare metal foil but it would not stick to the chromed part. Any suggestions?


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## Mark McGovern (Apr 25, 1999)

lis',

I assume that you want to retain the chrome plating on your wheel hubs. In that case my suggestion would be to remove the chrome plating on the wheels where they contact the vinyl tires. There are any number of removers for this, the simplest being to sand the wheels with fine sandpaper; 600-grit or finer would work. Then I'd brush paint a coat or two of gloss black, let that dry thoroughly, and apply the Bare-Metal Foil over the paint.

There are other barriers between the vinyl tires and plastic wheel hub you can try. Or maybe aftermarket wheels and tires made in resin or metal that won't interact. This is only the first reply, you'll get plenty more suggestions before you're done with this thread.


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## Richard Baker (Aug 8, 2006)

Wouldn't the chrome help protect the hubs where the rubber tires have physical contact with it?


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## liskorea317 (Mar 27, 2009)

Richard Baker said:


> Wouldn't the chrome help protect the hubs where the rubber tires have physical contact with it?


That's what I was hoping. I'm going to dip them in some Future and hope for the best!


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## irishtrek (Sep 17, 2005)

Do you want the wheels to have a chromed finish or something else like say aluminum?? If it's the latter then just remove the chrome and paint the wheels aluminum.


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## djnick66 (May 2, 2008)

Either way, chrome or paint will provide a barrier between the rubber and the tire. No need to reinvent the wheel and make more work than is necessary.


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## Owen E Oulton (Jan 6, 2012)

This problem has been around for half a century, It was especially problematic in the 1950's when they were just learning about plastic compatibilities. Back then the faux-rubber tires would turn whole wheels to goo over the years, right throught the plating. Your best bet is to assume that today, the chrome plating is even thinner, in an effort to reduce the clogging of the detail and take measures.


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## liskorea317 (Mar 27, 2009)

irishtrek said:


> Do you want the wheels to have a chromed finish or something else like say aluminum?? If it's the latter then just remove the chrome and paint the wheels aluminum.


I would like to keep the chrome as it is as its very bright. The original kit had plain plastic that had to be painted silver, and didn't look quite right.


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## djnick66 (May 2, 2008)

Chrome will provide a good barrier. The biggest issue in the past came from tires melting into kit parts in the box.... you open a kit and find the tires melted through the windshield. Paint will also provide a barrier. Acrylic paint seems to work really well for this. It's not a big deal though to take care of... You dont need to strip the chrome or anything drastic. 

For what its worth - if you fish, and buy tackle boxes, you probably see ones that say "worm proof" - fisherman have the same problem with rubber worms and lures melting the plastic trays in their tackle boxes.


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## liskorea317 (Mar 27, 2009)

Well, thanks everyone for your replies! I managed to find some kitchen foil in a supermarket today-it comes in a roll about 2 inches wide and has an adhesive backing and sticks to the chrome better than the bare metal foil. I cut it out and fitted it over the chrome that meets the rubber tires so it should be OK now. I also got some Tamiya brick diorama sheets to keep the tires separated from the plastic display case, and that enhanced the look a great deal!


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## Dyonisis (Nov 11, 2009)

Before you go any further - try using WAX to seal the chrome plating on your wheels. I know that this sounds stupid, but it will work, and nothing will leach into it. Just get an old coffee can (the big ones), then melt the wax slowly over the stove top. Then brush the wax over the part where you don't want to contact. Just melt the wax long enough to make it soft, but not hot enough to burn you, or your part. You can also use Brasso to remove the chrome plating with a cotton swab if you ever need to. Just remember to rinse it off afterwards. I'd only do this to parts where plating needs to be removed for gluing. Good luck! ​


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## djnick66 (May 2, 2008)

Wax over the chrome wheels will look like they are dipped in Chapstick and it is totally unnecessary. A simple coat of acrylic paint, a layer of chrome plating, or some aluminum foil is all you need. You don't need to protect or cover anything that is not in direct contact with the tires.


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## Dyonisis (Nov 11, 2009)

djnick66 said:


> Wax over the chrome wheels will look like they are dipped in Chapstick and it is totally unnecessary. A simple coat of acrylic paint, a layer of chrome plating, or some aluminum foil is all you need. You don't need to protect or cover anything that is not in direct contact with the tires.


Not if you do it right. I didn't say dip them - just BRUSH the wax over the backside of the rims. It the tires are acidic enough to eat the wheels, they'll be acidic enough to eat the paint, or any other similar covering. Wax is neutral, and won't absorb most household chemicals, so no fear of it eating your wheels too!


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## TAY666 (Jan 8, 2000)

The tires are not acidic.
It is a chemical reaction between the rubber and the styrene.
You just need a barrier between the two.

Much like you need either an acrylic or lacquer barrier between vinyl and enamel paints. Because the 2 together cause a chemical reaction which prevents the enamel from ever curing.


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## Owen E Oulton (Jan 6, 2012)

The chemical in question is known as a plasticizer. It keeps the vinyl tires, track and what-have you supple. Without it, thy'd become hard and brittle. The thing is, the problem has been known since the 1950's, and alternative plastics developed. There is no reason for the manufacturer to be using this type of plastinc for tires and tracks. I have many tank models from Tamiya and other companies, and none of them have this issue. It is something that just _*should not*_ be happening in the 21st century!


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## djnick66 (May 2, 2008)

Hobby Boss tires and tracks can melt the plastic wheels in their kits. I have not had Tamiya tracks melt anything, but their new gluable formula vinyl tracks decay, turn hard and brittle, and will crumble. This happens faster when painted with enamel paints, but they can go bad "in the box". Dragon's funny yellow Dragonstyrene tracks also do this... they can decay right in a sealed box. 

Apparently there are issues not just with the rubber or vinyl formula, but the formula of the plastic in the kit itself. The Moebius Lost in Space Chariot had issues with the rubber tracks and tires melting into the silver plastic parts. Moebius noted that this was the same plastic and rubber formula used by Round 2 in their car kits and no issues had ever happened. But, Moebius had done all their test shots in white or grey plastic only. When they added silver colorant for the actual product run of the kit, that is when the melting issue occurred.

Italeri tank tracks seem inert, but Italeri tires can melt the kit sprues.


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