A few questions for the plastic injection masters!?

[hollywood]

I just had the finish on the bottom of my presto pot start to wear and the plastic is sticking and burning instantly while heating it up.  I am not getting the plastic to even 325 before I see burnt plastic floating.  I am stirring constantly during the heating process and I have never had any burning issues until I notice the non stick surface start to thin.

How do you guys heat a lot of plastic, 4-8 cups or more (64 oz +) at a time?  So far we have been using presto pots but if the non stick surface wears off then they are not much use as the plastic is burning easily.

What do you use to stir the plastic without introducing extra bubbles or air?  I have a high temp silicone spatula but it seems to introduce bubbles.  Metal stirrers might scratch non stick surfaces.  Any ideas on what works best?  I like to heat the plastisol up to 350 and drop it down to around 300 degrees for the rest of the time. This seems to work great and prolongs the time I can inject.

Would a heating element and separate pot work better than the presto?  We do a lot of lighter shades so keeping temp in check is a must.  Thanks for the help guys!

[Frank]

I do a lot with prestos and never really had it burn but for 28 dollars the heating parts can't be the best. Whole sale on the unit must be around 16 dollars. If you try and make a pot to heat plastic those parts will cost you a pretty penny. My only advice would be use a microwave and transfer it to the presto. This way you would never have to get the presto up to that high of a temp. Let the micro do that. This way when you transfer it to the presto the temp would be much lower. Seems to me that pot is either full on or off. So starting it from a virgin state could make it produce heat that would cause burning.
On the non stick portion again it is a 28 dollar pot and you get what you get. Mine have not had the coating since about the first ten loads. The bottom of the pot is not smooth and really hampers cleaning in well. I just get as much plastic out as I can and let it cool. Then peel out what I can and use a wire brush to loosen the glitter on the bottom. Next I turn it over and get all the clumps out. Last i clean it up with laquer thinner. There still might be small piece in there but never seams to matter. On light colors I have two pot that are just for those color and those only. Two others for light colors with glitter and two for all others.
For stirring I just use some stainless welding rods bent up to scrape the bottom of the pots. I think they are about a 3/16 or 1/8 diameter and just the basic design does not introduce as many bubbles as products with a flat side. I know what you mean about light colors and bubbles. Hope this helps. Frank

[hollywood]

Good info.  Do you heat up your plastic in a microwave or just heat it with the presto?  Do you slowly turn it up or set it to a certain temp? 

I was thinking I could by a stand alone electric heating element then use higher quality pots to add my plasticol too. 

[hawgthumper]

I've been using these pots for years and honestly have never had this problem. I've still got my first old pot and it's as bald as a peach and doesn't burn the plastic. You may have a bad  element. I'm also wondering how you check your temperatures. A good IR or some other type of thermometer is absolutely essential for this stuff. This is the one place I would advise you no to skimp. It'll save you a lot of money and headaches. I also use stirring systems in all my pots. I get much more even heating with them. The bubbles release better too. Unfortunately, the wearing off of the non stick surface is just part of using these pots.  Especially if you use a lot of salt in your baits. That's all I use that one old pot I mentioned for. Good luck. 

[hollywood]

I have a good IR thermometer.  I'v been doing this for a while, just have never had this issue with my presto pots before.  I do not use salt in them.  I may just try heating it up slower.  I noticed that with 4 cups of plastisol in my presto that it has a hard time getting it up to 350 on my IR thermometer.  It will get to around 340 and then that extra 10 degrees takes a while. I would imagine the plastisol at the 340 temp is getting to around 350 near the bottom.  Once I get it to 350 I back off and drop down to around 300 and it shoots well and in the past allowed for me to shoot a lot of baits without discoloration.  I add a drop or two of heat stabilizer occasionally if I am doing a large batch.

For you guys that use presto pots how do you heat your plastisol.  Do you just turn it to 350 and let it heat up while stirring?  Or 400 and stir, check temp?

hawgthumper,  where do you get your stirring systems?  Thanks for the help guys.

[hawgthumper]

Hollywood, I got my paddles and 1complete stirring system from Bears. I made the rest myself. I use 12 volt DC motors in a couple. Kind of a pain,  but they are much stronger than the AC motors. If you're considering a system,  I'd recommend going with the AC though. They work great and less headache.

On your other question, I usually just start it at 350 and make sure the motor is on and stirring. Take my temp readings while stirring. You get a much more consistent result this way. You can't let the plastic sit on the bottom too long or it will scorch. I think your problem is that you have a bad element. Like Frank said,  these things are cheap so it happens.  I've heard of a lot of inconsistencies between pots. I get them with mine. Either that,  or you're not stirring enough. I know this is going to sound dumb, but if you have more than one pot, Don't mix up the power cords. Just seems like they don't mix well. So to speak .

[hollywood]

I will just get a few more pots.  They are cheap.  I have been using the same power cord with two of my pots and will try keeping them with the unit that came with them.  It could be that I need to stir even more now that the non stick surface is wearing off. 

Do you guys think that getting the plastisol up to around 340 is sufficient for the chemical reaction to take place?  I noticed if it does not get hot enough the baits are cloudy and sticky.

I do not use glitter at this time and inject all of my baits.  I think a stirring machine might be a little overkill at the moment but I will look into them.  Thanks for the help guys!

[hawgthumper]

JMHO but the stirring system is not overkill.  You need to constantly stir this stuff when not injecting. Between 340 and 350 should get you where you need to be.  Once you get it up to temp and add your colorant you can back it down to 320 or so. You can inject just fine at that temp And you have less issues with yellowing.

[Frank]

Good info.  Do you heat up your plastic in a microwave or just heat it with the presto?  Do you slowly turn it up or set it to a certain temp? 

I was thinking I could by a stand alone electric heating element then use higher quality pots to add my plasticol too.

for heating a gallon this is what I do. Pour one quart of raw plastic in the pot. Micro the second. Pour it in the pot and repeat two more times. The setting on the presto comes from using it a lot and I pretty much don't move it. They are all different but one is like 50degs off. Setting it at say 350 will make the element go way above that temp to stabilize itseft. I think that is where the burning is coming from. Frank

[ctom]

When using these pots with the reostat heat control, fill a new one with clean cooking oil and begin heating it and check in the temperature with a digtal thermometer as you move the dial higher. Check after each increase and allowing time for the oil to heat. Be sure to stir the oil just like you would plastic before you do the temp check. Keep a written record of where your working temps are found on the dial. Some of these pots have horridly inaccurate heat dials. Using the cooking oil allows you to check things before you use plastic and the oil can be cooled and returned to the original container for use in the kitchen and the oil is way cheaper than burnt plastic. Cooking oil is roughly the same weight as the raw plastic and will give you a real good idea of where things should be set at while water is way thinner and lacks the density that plastic and oil have. Water will heat entirely different.

[Denny Welch]

Tom,

You and Frank are what makes this (and other) forums tick.  Call them tricks of trade or just a willingness to share your many, many,  mmany, mmmmaannnnyy years of experience.  Thanks.

[ctom]

Man you make Frank and I sound like we should have lichens growing behind our knees.

[hollywood]

Thanks for all of the help.  I have probably injected about 40 gallons of plastic without any issues in two of my presto's but it seems like since the non stick bottom is wearing off it is changing how it heats.  I will go through and use some of whats been said here and try to fix the issue.  Its to bad these presto pots aren't more consistent.  I like the oil idea and will use that when I get some new pots.  Thanks.