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Kwalter32

Does this mean the plastic is burnt?

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Heated it in a bunsen burner and the temps would get to 320 then drop then back up. It started steaming and smelling burnt and now its yellow with a glob in the middle that wont mix in

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Yeah, I would say its burnt. Anytime you get smoke, the plastic is to hot and needs to be cooled off before burning beyond use. I would try stirring as you heat it to keep a more uniform temperature until you get a feel for how fast the bunsen burner heats up.

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1 hour ago, Driftwood said:

Yeah, I would say its burnt. Anytime you get smoke, the plastic is to hot and needs to be cooled off before burning beyond use. I would try stirring as you heat it to keep a more uniform temperature until you get a feel for how fast the bunsen burner heats up.

Ok thanks. I figured the some was just from it getting hot. I stir it with the thermometer needle but it seems to jump around on temp since the burner goes on and off 

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I wouldn't mess with a burner. Get yourself a hotplate. Much easier to control heat.

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 If he's using those pouring cups he can't put those in a micro. He'll have to get pyrex cups to do that; But I do agree that a micro is easiest of all.

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I bought 2 pyrex cups also to use the microwave but I figured the burner would be easier to keep an eye on the temps with. Only made one batch since the plastic kept dripping down the side and starting a fire. I dint recommend that method to newbies lol

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It might be only 320F where your reading with your thermometer; especially if it is an IR type. Right where that flame is hitting that pan that plastic is probably easily 400F +. Its called a "hot spot". Constant stirring will help but with that setup you'll never not burn plastic. For a small amount like that you cant beat a cheap microwave.

Did you add any hardener to that mix? That may explain the blob that wont mix in.

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11 minutes ago, McLuvin175 said:

It might be only 320F where your reading with your thermometer; especially if it is an IR type. Right where that flame is hitting that pan that plastic is probably easily 400F +. Its called a "hot spot". Constant stirring will help but with that setup you'll never not burn plastic. For a small amount like that you cant beat a cheap microwave.

Did you add any hardener to that mix? That may explain the blob that wont mix in.

I have hardener but wasnt sure how much to add to 4oz of plastic or when. I'm just going to get a microwave for the garage. 

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28 minutes ago, Kwalter32 said:

I have hardener but wasnt sure how much to add to 4oz of plastic or when. I'm just going to get a microwave for the garage. 

Be sure you mix in your hardener completely before you heat your plastic, or you will get lumps.

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On 5/14/2019 at 11:18 AM, mark poulson said:

Be sure you mix in your hardener completely before you heat your plastic, or you will get lumps.

+1 if your using the thicker type hardner you will want to add some heat  stabilizer . Mix the crap out of it .  In general my rule of thumb is:

4 oz soft plastic 

teaspoon of hardner gives me medium soft

table spoon gives me a medium hard

both require 5-10 drops of heat stabilizer 

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I never had much luck with hardener.  Always got lumps.  Then I don't pour much anymore either.  Just enough for my own use and to do a little testing as needed.  
 

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You need a thicker pan the thin metal will hot spot with the burner. I will agree with the others on microwave thrift stores are a good place to get one cheap or a return store. Also some plastisol turns yellow easier than others. Been there done that. Mix with black or dark colors when u get some that yellows Cub48

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