This Never Happened Before

[Tiderunner]

Been shooting a bunch of stick baits these past couple of days. I'm using MF medium with added MF softener, black, with lots of .062 glitter. Using the Do It  Gary Yamomoto molds,.

Heated my plastic, shot 8 baits, had dents in three. Molds and injector were preheated. Next run, 8 baits. I noticed plastic was kind of "lumpy", so I heated it some more. All looked good, though plastic was smoking a little. Shot this 8, let them cool, and tried to open the molds, and they wouldn't open. I finally pried them open, and the baits had more or less turned into, for lack of better description, glue. Rubber cement to be more specific.

I got most of the stuff scraped out of the molds. The rest of the seized rubber is going to need a solvent of wire brush. In 30 years of bait making, this has never happened. Has anyone here had that happen? Too much glitter maybe? Maybe too much glitter turned the plastisol into some other compound? It's not easy getting flake to show up through black. Too hot? It was smoking. I usually don't worry too much about black plastics,it's not like black can yellow,  and I've used too hot plastic before.

It's weird because this plastic was a reheat, and I noticed when it cooled inside the measuring cup I removed the puck, and it was difficult removing it because it had stuck to the pyrex cup. I got the puck out, and couldn't clean the cup. I was/am going to trash that one.

Like I had already said, never had something like this happen before, and in all these years I've made plenty of mistakes, but this one is a first.

Lastly, does anyone have a better idea to clean this besides solvent and a wire brush?

 

[Arne]

Really do not know anything about pouring plastic baits, but reading your post my first thought was put a little acetone in your measuring cup.  Will that cut the plastic so you can save the cup?  Just a thought, sorry but can't help with your pouring problem. Arne.

[Judgie]

I believe you over heated the plastic.

Happened to me once.

Very difficult to clean up.

[Tiderunner]

2 hours ago, Judgie said:

I believe you over heated the plastic.

Happened to me once.

Very difficult to clean up.

I believe you're right. And both counts. Goop is like a glue. Stuck to the measuring cup, two Yamamoto Senko molds. Even the knife I was stirring plastic with. Being it was black plastic, I never paid too much attention to it. I mean how do you discolor black? Molds are now soaking in worm oil, and another in WD40 before I go to the solvent method.

 

3 hours ago, Arne said:

Really do not know anything about pouring plastic baits, but reading your post my first thought was put a little acetone in your measuring cup.  Will that cut the plastic so you can save the cup?  Just a thought, sorry but can't help with your pouring problem. Arne.

If the oil or the WD40 ( that is a solvent actually ) don't work I'm going right past acetone to lacquer thinner. So far both oils are working slowly. The measuring cup is over 5 years old, and I'm afraid of leaving micro scratches in it. I may just trash it. Or maybe lacquer thinner that and just relegate it to the garage.

[Tiderunner]

Update. Tried softening burnt on plastic with worm oil on one side and WD40 on the other. So far the WD-40 is winning, but far from perfect. Today is lacquer thinner day! Update on this to follow.  Advice to all here. Don't burn your plastisol, and if you do, don't inject it. I makes a really big mess that takes a lot of effort and time to clean. Let my stupid mistake help you prevent this.  ( I'm sure this won't be my last fudge up )

[Les Young]

If it's  a  brownish/ black (without the colorant) & bubbly it's definitely burnt. If i do burn it i immediately pour it out & then when the cup cools i clean it up & use it next time i shoot.  The smoking burnt smell is awful & toxic if you breath it too. 

[Tiderunner]

14 hours ago, Les Young said:

If it's  a  brownish/ black (without the colorant) & bubbly it's definitely burnt. If i do burn it i immediately pour it out & then when the cup cools i clean it up & use it next time i shoot.  The smoking burnt smell is awful & toxic if you breath it too. 

Didn't seem burnt. This was a reheat. Reheated multiple times. I'm wondering if the glitter had melted and added a different component to the plastic, as I kept adding glitter with each reheat. I didn't bother trying to save the cup. I let it cool and tossed it. Plastic was hard as a rock. Never, in all the years doing this have I ever seen plastisol  do this It was stronger than any adhesive I have ever used. Couldn't scrape it out of the cup. Out of the mold. Even off the knife I was stirring with. Was going to soak molds in lacquer thinner. Which should dissolve the plastic. But I didn't have any. Had denatured alcohol, so trying that. Then heading over to a big box store with orange roof and paint. To pick up some lacquer thinner. I refuse to have this mess beat me. I hope to have these molds cleaned up by the end of the day.

[Psy]

I had something happen where my plastic burned because I placed it, by accident, dead-center in the microwave.  I was using a neon pink mica powder and thought that was what caused it at first, until I noticed that I accidentally placed the cup dead-center.  Never do that.  The middle will get far too hot and you're not going to cook your plastic properly.  Not saying that's what happened here, just saying it's what happened to me.  

[Tiderunner]

On 3/2/2025 at 4:50 PM, Psy said:

I had something happen where my plastic burned because I placed it, by accident, dead-center in the microwave.

I always place my cup in the middle of the microwave. I do only cook the plastic in short bursts. No more than a minute each time. Then as I'm getting close to desired temp I only cook in seconds, and check temps.  Never had an issue . Except this past time I guess. I also don't have a powerful 1000 watt microwave. Mine is 650 watt I believe. I'm wondering if the mica had more to do with the burning rather than placing cup in the middle.