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Plastic material type used in models

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  • Member since
    November, 2017
Plastic material type used in models
Posted by twex on Sunday, November 05, 2017 3:59 PM

After google and manufacturers websites failed to provide an answer it might be time to ask some nice people: 

 

What type of plastic materials is typically used in model kits? 

 

It probably gets mostly shaped by injection molding. I would guess 

it might be an amarphous thermoplastic. But I am already wildly guessing here.

 

I know, it is a strange question to ask. But maybe somebody else already has found the answer?  

  • Member since
    December, 2002
  • From: Fort Knox
Posted by Rob Gronovius on Tuesday, November 07, 2017 11:32 AM

Polystyrene is the type of plastic used in injection molded model kits. But even the plastic can vary from manufacturer to manufacturer. Some manufacturers use very brittle plastic and others seem so soft that the surface mars if you stare at it too hard.

Many Eastern European model companies' plastic is very brittle and will shatter and snap as you cut it off the sprue. I know when I build AFV Club armor kits, the plastic is so soft  that if you use a thumbnail to press a part into place, sometimes you leave an indentation in the surface.

The old MPC company was notorious for having soft plastic. Too much glue and you'd get a melted blob.

https://en.wikipedia.org/wiki/Polystyrene

  • Member since
    January, 2013
Posted by BlackSheepTwoOneFour on Tuesday, November 07, 2017 11:55 AM

Polystyrene. What other plastic would there be? Aftermarket items like wheels/tires, gear struts, engines are typically resins. Some  gunbarrels can be resins or brass.

Depending on the brand, some can be brittle, some soft, etc...

  • Member since
    November, 2017
Posted by twex on Tuesday, November 07, 2017 12:26 PM
Thank you for this information. Looks like there is allot of variance in Polystyrene. The usual cheap vs good rules seem to apply.
  • Member since
    November, 2017
Posted by twex on Tuesday, November 07, 2017 12:27 PM
Thank you. There are 100s of plastic materials. PS (recycle symbol 4) makes sense.
  • Member since
    October, 2010
Posted by hypertex on Wednesday, November 08, 2017 9:24 AM

twex
Thank you. There are 100s of plastic materials. PS (recycle symbol 4) makes sense.

Polystyrene has the recycling symbol 6. See here.

99% of plastic kits are Polystyrene. But there are others.

There are a few ABS kits around, such as Pegasus' Terminator Tank. A to Z Models releases kits in Polyurethane Resin (PUR), which is not thermoplastic.

There are also a few companies that throw in bits of other stuff. Tamiya and Bandai are fond of what they call "polycaps", which are a soft plastic that is either Polypropylene or polyethylene (can't remember which). Bandai is even known to mold half of a sprue in polypropylene.

Often, especially in modern kits, manufacturers will label the type of plastic on the revers side of the sprue. I've seen PS, PP, PE, or PVC. So if you are in doubt, you can look for that.

Then there are the rubbery tires or tank tracks that are made of some type of rubber or vinyl (or something in between).

  • Member since
    June, 2014
  • From: New Braunfels , Texas
Posted by Tanker - Builder on Wednesday, November 08, 2017 12:52 PM

Hi;

 From my experience it seems it's this way .  Most companies use a " Virgin " Styrene .Then before it gets to the machines it is mixed with grade one ground plastic that is recycled . Now this will vary by company and cost analysis their bean counter says is needed . 

 Some of these guys are so Retentive they insist on as close to 40% as they can get . When you do this however the plastic becomes brittle . On the other side if any Poly pro - is used ,say 10% ,  maybe then glue doesn't work as well and also the recycle number changes .They hope ( in the front office ) that if thrown away , it goes in the landfill anyway .

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Thursday, November 09, 2017 8:34 AM

Tanker - Builder

Hi;

 From my experience it seems it's this way .  Most companies use a " Virgin " Styrene .Then before it gets to the machines it is mixed with grade one ground plastic that is recycled . Now this will vary by company and cost analysis their bean counter says is needed . 

 Some of these guys are so Retentive they insist on as close to 40% as they can get . When you do this however the plastic becomes brittle . On the other side if any Poly pro - is used ,say 10% ,  maybe then glue doesn't work as well and also the recycle number changes .They hope ( in the front office ) that if thrown away , it goes in the landfill anyway .

 

Interesting!  I have found some kits that didn't work well with some solvent glues- maybe that is the reason.

 

Don Stauffer in Minnesota

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