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Vinyl on Sprue?


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I just read a review where they mentioned keeping vinyl parts (tires) off unpainted sprue pieces. I have never heard of such a thing. What happens? Is this one of those common things that I have never heard before? Is this something to be concerned about?

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There's something in some vinyl parts that will attack the plastic, first causing the tires to stick to the plastic, then slowly starting to dissolve the plastic. It seems to be common to lower grades of vinyl parts (ie made in China), I've not heard of the problem with HQ vinyl parts like those found in Tamiya kits.

The problem first showed up back in the 90's when AMT was releasing some of their new-tool 1/48 kits with vinyl tires, people that bought the kits a few months/years after the release noticed that the tires stuck to and dissolved whatever plastic that they touched. (IIRC when the kits were packaged the tires were just tossed in the box, they weren't bagged separately)

Recently the new Lost-in-Space Chariot kit from Moebius had the same problem, the vinyl tracks were sticking to the plastic by the time the kits were in the hands of modelers. I think they were going to change the vinyl for the rest of the run.

If I bought a kit with vinyl parts I'd make sure to inspect them and bag them separately as soon as I got the kit, and if the parts were easily replaceable (like tires) I'd look at getting resin replacements to avoid any problems in the future.

Ken

Edited by kenlilly106
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OK...something to think about. THX! Question though: They mentioned unpainted/ painted parts. Would it not matter if the parts are painted? What about vinyl tires on plastic hubs? I would hope painting them would make a difference. I built a motorcycle a couple of years ago and it has vinyl tires on plastic hubs. I did have to paint the hubs. Although, now that I think of it, it was a Tamiya kit.

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Hey Jetdx, I believe that the fix for plastic-disolving vinyl is to coat the vinyl. IIRC, other modellers have used Future for th job. I suspect, use Future coat/s to seal th vinyl, then a clear flat to restore the finish of rubber.

George, out.........................

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The problem is that the plasticiser in the vinyl leaches out and eats away at the polystyrene. In theory a solid barrier between the two ought to prevent this. Paint, varnish, anything, so long as it's not porous. However, I have my doubts about this, for two reasons. One, I'm not sure how good a paint barrier can be - I've not actually tried it yet. And two, if the vinyl is losing plasticiser, it will tend to go hard and brittle and will then disintegrate. Coating it completely in paint ought to help with this, by trapping any vapours that are trying to leave, but it still seems a bit dubious to me. As a rule, if research reveals a problem with vinyl parts, I replace 'em. The resin stuff is often better anyway.

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