Random "yellowing"

[jslager]

Ive not been doing this for years but I have shot approx 20 gallons of Plastic. The last few sessions I have made Lighter colored baits I have gotten VERY bad yellowing. It has only happened on this particular "container" of plastic I'm using.

But, before I blame the plastic could something else be causing the issue? The first time i noticed iut i was shooting a laminate of 2 light colors and it happened to both colors. different, pots, stirrers ect.. I did use a microwave on remelting some of the scraps to reshoot so it is possible I over heated. However, I just finished up a whole new batch and it happened again and I did not use the microwave at all and I was VERY diligent to make sure nothing went over 370.

Any ideas? could I just have a bad batch of plastic? or should i be looking at something else?

Thanks in advance.

[Denny Welch]

It's been my experience that light colors and temps over 350 degrees are a recipe for disaster.  You didn't mention using heat stabilizer so I assume you didn't.  If I had to guess, I'd say the plastic got too hot which in turn caused yellowing.  I suggest you try another small batch of the same plastisol.  Put in 5 - 10 drops of heat stabilizer if you have it.  Heat it slowly in 30 second increments and continually stir it after each heating.  Do not exceed 350 degrees.  Inject the molds and, hopefully, you won't have the yellowing problem.  Good luck.

[jslager]

It's been my experience that light colors and temps over 350 degrees are a recipe for disaster.  You didn't mention using heat stabilizer so I assume you didn't.  If I had to guess, I'd say the plastic got too hot which in turn caused yellowing.  I suggest you try another small batch of the same plastisol.  Put in 5 - 10 drops of heat stabilizer if you have it.  Heat it slowly in 30 second increments and continually stir it after each heating.  Do not exceed 350 degrees.  Inject the molds and, hopefully, you won't have the yellowing problem.  Good luck.

Interesting, I didn't think you'd need to worry about yellowing around 350. I was under the impression that you needed to get to 350 to "activate". I've never had this problem till this week. I will try and keep my light baits under 350. Thanks.

[jslager]

Also, this was fresh plastic. I will start adding heat stabilizer even to fresh plastic just to be safe

[CrabbyBass]

I would also make sure you are shaking up the raw plastic in the bottle really well.  The components tend to settle out and need to be mixed to stay in solution.

[kipbass]

Fresh plastic must be heated to 350 degrees in order for it to work properly. Reheating old plastic doesn't need to be that hot. If you're heating fresh plastic to 370, I would back off to the 350 mark.

[andrewlamberson]

If it is CCM plastic...you really need to get it to 350 to avoid sticky or cloudy plastic (I don't know about other brands). That being said....you don't want it to get above 360 ANYWHERE in your cup. Microwaves don't heat evenly  so heating in small increments and stirring is a must. Also remember that any liquid that is microwaved continues to increase in heat for up to a minute (or more). So if you stop at 350...it still may go up to 355 or 360. Read all the posts (and there are a bunch!) on the topics of microwaves, temperature etc on the forum.

As I've mention "a few" times in previous posts...you really need to have a good digital thermometer like the one that Do-it now sells. I use the probe to stir. You will be amazed how part of your plastic may read 340...and another spot 360 (especially at the bottom and center of the cup).

[Denny Welch]

Andy..."a few"...gimme a break.

[kipbass]

Andy..."a few"...gimme a break.

LOL!

[Justin9j]

^^^^^^^^^^ funny guys.