Modelling > Tips, Tools & Techniques

Rubber vs Plastic

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Jeffry Fontaine:
This issue has cropped up on several forums in years past and addresses the rubber parts that react to certain types of plastic.  The most recent discussion on this topic was found on Missing-Lynx and I thought it would be prudent to share the link to that discussion here since we tend to be more "multi-media" type modelers and may have encounter this problem in past builds or to at least forewarn you of what to expect in future builds where rubber parts are used with your model kit parts and they chemically react. 

Here is the link to the discussion from Missing-Lynx: "Rubber" tires eating away styrene

Frank3k:
I had an MRC 1/35 scale Huey gunship kit that had a vinyl ammo belt packed in with the clear parts! The belt melted a curve right into the windscreen that would have been impossible to sand out or fill in. Luckily MRC sent me a replacement. Since then, I'll remove the vinyl parts from any kit that has them and put them in a separate bag (if they aren't already bagged separately). I haven't had any issues with built kits and vinyl parts, but I always coat them with Future or paint.

AMT had a similar issue in the 90s with their 1/48 F7F Tigercat. It came with vinyl tires and many kits were ruined when the tires melted into random bits of the kit.

Jeffry Fontaine:

--- Quote from: Frank3k on January 12, 2012, 11:46:21 AM ---AMT had a similar issue in the 90s with their 1/48 F7F Tigercat. It came with vinyl tires and many kits were ruined when the tires melted into random bits of the kit.
--- End quote ---

I experienced this issue with one of the Tigercat kits.  The rubber tire had been in contact with the upper wing and left a crescent shaped scar in the plastic.  Strangest thing I ever saw and makes you wonder what AMT/Ertl did to the rubber mixture to cause that.  I had many model cars when I was younger and most of these had rubber tires which were in constant contact with unpainted plastic and I do not recall any reactions between the rubber and polystyrene in any of these models. 

The rubber ammunition chute has me concerned, I may have a couple of those UH-1 kits with the rubber parts in the same bag as the clear parts.  Need to check on that soon. 

jcf:
Hi Jeff, as Frank alluded to, the problem is that 'rubber' parts in model kits aren't rubber,
they are various formulations of vinyl, some of which can remain chemically reactive after
forming. One thing I've noticed is that the softer and more flexible the parts, the more likely
they are to be reactive with polystyrene. The old school vinyl car tires are generally much firmer,
some being downright stiff.

 :icon_fsm:

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