Overheated plastic

[Denny Welch]

It's not too hard to become preoccupied with something and lose sight of something else.  I had some friends coming over yesterday to pour baits and I was heating plastic to preheat my molds.  I set the timer on the microwave for two minutes and then started playing with my new lamination plates.  I must have set the microwave for 20 minutes instead of 2 because when I looked over it still had 10 minutes to go.  Smoke was starting to seep from the microwave and I could hardly see through it's window.  I immediately turned it off and opened it's door.  I was only heating 4 ounces of plastic, but it had formed a mushroom head that was extending about 4 inches above the Pyrex cup.  Smoke was pouring from the blackened plastic and I had real fears that it was going to blow up at any moment.  I carefully picked it up and put it outside.  It didn't cool off for a half-hour.

It really shook me up.  Some of you have probably had similar experiences and I'm curious how you handled it.  I'd like to know what I did right and what I did wrong. 

I can't help but think what would have happened had by friends arrived early.  Clear as day, I can see one of them throwing a coke or a bottle of water on that hot plastic.  Can you imagine the result...it's scary.

[Justin9j]

Idont know if i would have picked it up right away.   

[Jason]

Yikes!!!  If this ever happens again I think I would just leave it and air out the building / room.  No doubt the plastic exceeded 500 degrees and this is when it becomes dangerous to breathe.  Glad everyone is okay - be careful!!!

Jason

[BassDetective]

Jason - do you have an MSDS on the plastic?  Those types of documents usually provide guidance about how to handle the material in situations like this.  Since water is not an option - is there a type of fire extinguisher or other smothering agent that you can use in the event of an emergency?

Really good topic thanks for sharing.

[Jason]

Yes, the MSDS is on the plastic page towards the bottom before the video:

http://www.caneycreekmolds.com/Caney-Creek-Crystal-Clear-Plastisol-Phthalate-Free_p_181.html

Barring an emergency of fire being present, my biggest concern would be not to breath the smoke.  Once it hits 500+ degrees PVC puts off dangerous toxins.

Jason

[Dave]

Barring an emergency of fire being present, my biggest concern would be not to breath the smoke.  Once it hits 500+ degrees PVC puts off dangerous toxins.

Jason

This is what I referred to when i posted a while back on burning plastic and breathing it. It was horrible. I am going to print a copy of the msds and take it to my doctor so he can get me back on track! 

[BassDetective]

I just read the MSDS - thanks for posting.  It looks like most of the information applies in a non-heated state.  It does reference to not keep the temp above 300 F for prolonged periods.    The NIOSH recommendations for respirators is non specific.  There are different types of respirators.  Some are only good on particulates and some are rated for chemical.  There is a big difference.  I work outside with plenty of ventilation but I still use a respirator because I often find myself right above the cup and within inhalation distance (i.e. when hand pouring).  Also a slight breeze can bring the vapors your way too.

[kipbass]

Mr Denny I'm glad you're ok! God bless you.
I had a small amount of water in my Pyrex after cleaning and didn't realize it was there when I heated my plastic. It popped and crackled, I kept the microwave door between me and the cup while stirring. That was pretty scary at the time.

[Ed Brabant]

OK ready for what I remembered for my plastics processing class. There is a name for what happens it is call auto catalytic chain unzipering. The by product is HCL and chlorine. The base material is PVC. Very nasty when you over heat it. And you DON"T want to breath any of the fumes.

[Dave]

Thanks Ed, that is great to know now. 

[BareKnuckleJigs]

Praise GOD You're Ok, Mr. Denny!

My guess is that You either punched "22" trying to hit "2", or You intended to punch "2:00" and hit "20:00".

We never stop learning.  Double Check Everything...