Plastic 101 (Plastisol)
This is not an exhaustive resource for Plastisol, but a practical guide to the plastic used to make soft plastic baits. It may not apply to all brands, but the principals should apply to most PVC based plastics. Where possible I address "non CCM plastic" based on my experiences.What is it?
At a high level Plastisol is made up of 3 main components: Polyvinyl Chloride (PVC), Plasticizer, and Heat Stabilizer. In the case of CC plastic we use a blend of Plasticizers and Heat Stabilizers. Below is the function of each:Polyvinyl Chloride (PVC):
Is the plastic. It's what gives the worm mass.Plasticizer:
This can be many different things, but ultimately is what softens the plastic so it's not hard like a PVC pipe. Plasticizer is also what's used in some scents, added to pigment to make colorant, and is also called worm oil, softener, etc. As I mentioned, there are many different kinds, each with it's own unique properties. An example is our Softener and Worm Oil, both are Plasticizers, but one produce a dry feel, while the other is oily (worm oil).Heat Stabilizer:
Heat Stabilizer can be many things (barium, zinc, etc.). Virgin plastic contains heat stabilizer, but more may be needed based on how long and/or vigorously you heat your plastic. I'll explain more below.New Plastisol
Plastic still in the container (new plastisol): PVC, Plasticizer, and Heat Stabilizer do not weigh the same. With our formula we have tried to keep the components as close as possible to prevent hard pack, but it will still separate (just like ketchup in a bottle gets water on top when it sits for a while). With CC simply turning the box over several times will cause it to all re-suspend again. If it's been sitting all year it may take a few more turns than normal.
What happens if I don't mix my plastic well?
With most brands it will settle and you will pour primarily plasticizer from the top of the container. The result is baits that are like jelly and will never setup. The reason should be obvious given the above information, because it is not mixed well, you are getting a disproportionate amount of plasticizer (softener) vs. PVC (your formula is out of whack because you didn't mix it well).
With CCM Plastisol we've tried to minimize this two ways: 1) We formulated a Plastisol that doesn't hard pack, and 2) we made it pour from the bottom. Does this mean it is problem free? Unfortunately no. It is still susceptible to separation, however, it is the opposite since you are pulling from the bottom of the container. Forgetting to roll it over before use can cause one of two problems. Depending on how long it sat you may not notice until you get to the end and there is more plasticizer (softener) and not as much PVC. This will produce jelly worms (it's still useable but will need to be blended with new plastic that you don't forget to rotate). The other potential problem arises if you forget to rotate it and the stabilizer is pulled out disproportionately. Both scenarios are less than desirable, but can be managed by recognizing the problem and adjusting accordingly. The ideal thing is to always rotate your box and avoid the problem all together.The cooking process...
It is critical that all
PVC be heated to 350 degrees for it to correctly cook. Failure to heat an entire batch to 350 degrees may cause your baits to "phase" (discolor, become oily, basically deteriorate).
During the cooking process the PVC splits, producing vinyl and chloride. In the absence of a Heat Stabilizer the chloride will reattach itself to the vinyl, causing the vinyl to discolor (yellow - or worse...). A key thing to note here is that a Stabilizer can only be attached to one time. Once the Heat Stabilizer has been attached to it becomes a byproduct in your plastic.
So there are some obvious questions at this point:
Why not just add a bunch of stabilizer so it's not an issue? To much stabilizer will produce an undesirable plastic. It could manifest itself as being difficult to work with, oily, smelly, discoloring, unstable, etc.
How much Heat Stabilizer should be added? I wish there was an easy answer to this. It depends on the amount of heat that is applied, and how long it is going to be applied (as both of these determine the amount of chlorides that are produced). This is where experience, experimenting and skill come into play. The key thing to note is that an excessive amount will keep baits from yellowing, but cause other undesirable effects, and not enough will allow the plastic to yellow (chlorides attaching to vinyl).
For a "typical heating process" we add enough stabilizer for it to be cooked in the microwave 3 times prior to adding additional stabilizer. With that said, there is no typical heating process because everybody's microwave, cook top, pot, etc. is different.
The only way "how much?" could be accurately answered would be if we all used the same equipment, at the same altitude, with the same amount of humidity. Even the color of colorant you use can make a difference.
Keep really good notes of what you are doing so you can refer back to them for future runs.Things to watch out for:
Microwave: a turntable is a must, watch for hot spots, heat can get away from you in a hurry, make sure it is thoroughly cooked - not just the top or middle, stir and recheck. Towards the end of cooking make small time adjustments - 15 seconds can be a long time if you're sitting at 340...
Presto Pots and the like (inexpensive heating sources): They are either on, or off. They come on full blast and don't shut off until the thermostat tells it to. This can be problematic if the plastic isn't moving, or you are working with a small amount of plastic. Make sure and stir - a lot, or get one with a stirring mechanism.
Direct Heat (Burner type devices): Same as presto pot, but if you invest in a device with a variable element it prevents the "blast of heat". Another alternative I have yet to explore is using a Cast Iron pot (sounds promising but I don't have first hand experience yet).Must haves:
A good thermometer. I know some don't use them, but how many chemist would produce a product and not control as many variables as possible - none that are currently employed? http://www.amazon.com/CDN-DTQ450X-ProAccurate-Quick-Read-Thermometer/dp/B0021AEAG2/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1353867035&sr=1-1&keywords=digital+thermometer
Proper Ventilation. It's not a luxury, it is a must have.
A respirator and proper personal protection (clothing), again it's not a luxury, it is a must have.
Keep really good notes of what you are doing so you can refer back to them for future runs.Additional Common Questions:
Once plastic starts to yellow can it be stopped by adding stabilizer? Maybe technically, but not really. Once you run it to the point it starts to yellow it's time to make it a darker color and call it quits.
When should I add glitter? Glitter is the most heat sensitive component in the process, add it last and try to minimize the heat it is subjected to.
When should I add colorant? You can add it at any point, but you will get the most vibrant true colors by adding it before you cook your plastic. It is also much easier to stir in when the plastic is cold (liquid) vs molten.
How do I make my baits softer? You can add softener (Plasticizer).
How do I make my baits harder? Most companies sell a hardener (PVC concentrated Plastisol).
Can I mix products from other companies? I have never heard of an adverse effect of doing so, but that doesn't mean it couldn't happen. Normally you will just end up with properties from both (mix an oily plastic with a dry plastic and you would end up with a slightly oily plastic).
Will my plastic freeze? CC plastic is good to -50 degrees. If you are somewhere it gets colder than that you need to move. - sorry
Max plastic temperature: Don't be afraid to get your plastic up around 360 / 370 as long as you are good on stabilizer. Make sure and never get it up around 500 degrees. 500 degrees is when it puts off toxic fumes.
Feel free to ask any additional questions you have. I will add to this as other questions are asked, but this addresses the majority of them and explains what's happening when you are cooking plastic.