restore the plastic in old kits

stikpusher

Isn't styrene impermeable to both water vapor or liquid...

To liquid, largely yes. But polystyrene is permeable to both oxygen and water vapor.

As a 'lowball' example, stretched sprue can sag with changes in humidity...just as nylon fishing line can.

Isn't styrene impermeable to both water vapor or liquid...

BlackSheepTwoOneFour

 

This would better to post in General Discussion thread, not in the Introduction forum.

Second that.  When I saw the post in the forum index, I thought, "What, again?  A new guy joins and posts a technical question in his welcome post?"

Old Silver Grizz

Having worked with a large plastic injection molding company over the years, I found out that the plastic will dry out and become very brittle.

An easy fix is to place the sprues in a plastic ziplock bag with about 2 tablespoons of water and seal. Let them sit for 3-4 days and they will rehydrate and not be brittle.

This really helps when you score a long out of production kit on your wish list.

I'm building some kits 20+ years old without any issues.

 

Happy building!

 

Old Silver Grizz

 

This would better to post in General Discussion thread, not in the Introduction forum.

Welcome and thanks for the tip. While "hydrating" plastic may be counter intuitive, I know it works in another context. The manufacturer of the plastic line I use in my line trimmer recommends storing it in water to retain or enhance it's flexibility. It works - the line is much easier to use and lasts longer.

Your suggestion is easy to test, and will come in handy on some old kits in the stash; AMT's Havoc and Viking, and the Classic Airframes SM79.

Mike

If I have to wait 3or 4 days for the plastic to hydration which I don' think going to work .I just put the kit in the trash. Welcome to the forum.

i have a problem with that in that styrene plastic used in models is oil based not water & oil & water do not mix well.