Author Topic: Preventing yellowing of plastisol  (Read 481 times)

Offline Jake Hendrickson

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Preventing yellowing of plastisol
« on: 01/11/19 08:16 UTC »
I wanted to resurface this topic as I have been trying to achieve both a sharp looking white, and a clear/silver color without the plastisol yellowing be the end of the batch.

I normally work in 6 oz batches, add my heat stabilizer, initial mircowave shot of 1:30, stir, and then 30 second hits until it gets to a desired consistency.  I will admit I dont use the thermometer nearly enough, so this could be where the problem is.  I have a 5 cavity mold, and will put the sprue and excess plastic from my injector back into my pyrex to then reheat.  reheats are usually 15-20 seconds, stir, back in.

a couple questions:   other than actually using my thermometer (i know, i know), is there something I'm doing wrong that by the end of the batch, my plastisol has turned a slight yellow, even with adding stabilizer?

I was thinking of trying an electric skillet to see if keeping the heated plastisol on that instead of hitting it with the microwave for reheats would be any better in not letting the temp climb, resulting in the yellowing.

Has anyone tried using silica sand in an electric skillet to help with a more uniform heat distribution around your pyrex?

long winded,   thank you for reading and thank you in advance for any helpful tips or advice.

Jake

Offline olsarge

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Re: Preventing yellowing of plastisol
« Reply #1 on: 01/11/19 09:05 UTC »
White/Pearlescents are tuff colors to keep from yellowing.  1.Microwave them in shorter increments (I do them in 30 second intervals.   Stir them in between each interval to avoid hot spots.  2.  Always use a thermometer-there is no substitute for it.  I use 4 ounces of plastisol as my standard that way I am usually out by the time that yellowing would occur.  If I see slight yellowing I will shoot it one more time as both the fish and I like bone colored baits.  If I still have enough plastic left, now is the time to add black flake/glitter.  This will turn it a silver color and you can shoot it as often as  you like.  Other than that, the best advice I can give is USE A THERMOMETER!
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Online MT204

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Re: Preventing yellowing of plastisol
« Reply #2 on: 01/11/19 11:48 UTC »
I had some problems with yellowing at one point.
I found if I use Flexible Silicone Measuring Cups for reheats the plastic stays warmer way longer so didn't have to heat as much between pours.

Online billygee

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Re: Preventing yellowing of plastisol
« Reply #3 on: 01/11/19 13:14 UTC »
Might i ask what type plastisol you are using
some are more prone to temperature yellowing then others

Offline superharmonix

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Re: Preventing yellowing of plastisol
« Reply #4 on: 01/11/19 15:23 UTC »
Might i ask what type plastisol you are using
some are more prone to temperature yellowing then others

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Offline brandx112679

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Re: Preventing yellowing of plastisol
« Reply #5 on: 01/11/19 19:21 UTC »


  Bingo X'2

Online ctom

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Re: Preventing yellowing of plastisol
« Reply #6 on: 01/12/19 10:10 UTC »
Jake .....

There are a lot of factors a person has to work around on some colors and white is not an exception. In fact white can be the worst color to work with.

Starting with white colorants themselves, there are many on the market. Some are less potent and require three or four times the drops of others. The thinner the colorant, the easier the learning curve. X2 colorants are super heavy, both in color concentration and in pigment load, and call for very few drops to make a nice solid white in a cup of plastic. The titanium white pigment in the X2 color is very heavy and dense by nature and will in fact absorb heat making it harder to figure out. When I do white using the X2 colorant I make sure its mixed well then , using a clean, empty bottle with a yorker cap, I add 1/2 bottle of the colorant and add the same amount of raw plastic and mix it by shaking the heck out of it. This blend will make your white with the same drop count as the X2 but has 1.2 of the pigment load so the pigment heating issue is roughly half that of the full strength product. Done as such its still much stronger than MF and Lureworks stuff, just easier to work with in getting rid of heating issues.

On the skillet idea.....I have a heat bed made from a square electric skillet that has cavities in silica sand for five 8 ounce pyrex desert cups. Shown here, is an empty cup except for a 4" Ripper and seen with a tape for size reference.



I mixed the sand with some water and elmers glue, then laid a bed of the sand mixture about 1/2" thick on the bottom of the skillets then spaced the five cups on the sand bed and filled in around the cups with more sand until the sand level was about 1/4" below the top of the lip of the cups. This was allowed to dry for several days before removing the cups to finish drying a few days longer yet. The cups were greased with Crisco before the sand was packed around them and they released right away when given a slight turn for the drying finish. I filled the cups with cooking oil and turned the heat on low, gradually increasing it until I hit a temp of 320 degrees in each cup, then I super-glued the rheostat in place. The oil got dumped. This gave me a hot bed that when plugged in went up to the 320 degrees without having to mess with constantly checking temps and cups that did not get filled with hot plastic from the microwave had junk plastic plugs in them so heating stayed constant. The junk plugs came out if the cups were needed.  If you're doing a bunch of colors, this system works well as long as you're not doing huge baits that constantly suck up the plastic in the cups. It works really well when doing  split colors as the different plastics stay at a usable heat level. I make small baits primarily and the system works great for this. Probably not super practical for big runs.

If you cook with a microwave, cut a corrugated cardboard palette to size that fits on the glass tray or rotisserie of the unit. Keep that on the tray all the time as it offers a buffer that will help eliminate hot spots inside the cabinet of the microwave and they all have these hot spots. It has to be corrugated cardboard, not the thin stuff used in gift boxes. This can go a long way in assuring even heating, which is a headache when doing light and clear colors.

Use the thermometer. Stop the heating on the initial cooking, a few degrees under the 350 degrees and let the cup rest a half a minute. Check the temp and you'll find that the plastic has come up several degrees. Cooking food shows this occurrence and plastic is no different. And keep in mind that heavy, dense colors such as white, will heat higher longer after coming from the oven....often enough to start the burning process slightly and once this happens its too late to start seeking a use for it if you want a clean color on re-heats or even the initial cook. You won't know any of this is taking place by dipping your finger in what you're cooking. Use the thermometer.

Not all plastics are created equal. The different weights [soft, medium, firm] in a specific brand of plastic will have different heating characteristics and a person has to figure out how long is enough or too long to push the plastic in a light color. It all comes with practical experience and there is no standardized worksheet that answers it all....only some suggested temps and cook times. When I am doing white I cook in much sorter bursts and stir the heck out of it at each stop. I use stabilizer at the initial cook but before I even use the white for an injection I add and stir in more stabilizer so when I have to re-heat,  again in short bursts, the stabilizer is already incorporated in the plastic. I do this when I am ready to inject every time I use a re-heated white. On clear plastic I don't add any hi-lite or glitter until the plastic is at the 350 degrees and the stabilizer goes in again when I add these components if a re-heat is planned. For me the Essential series plastic is the most forgiving plastic I have used, but like all plastics, one has to "learn" it, then learn the colors. Shortcuts don't work so well and usually lead people back to this point or to pissing and moaning about bad products when in fact its operator error.  Slow down, take lots of notes, USE THE THERMOMETER, and understand that all colors except for maybe black have a working life and once that threshold has been met, then black is your best option for future use.

Online Canga~

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Re: Preventing yellowing of plastisol
« Reply #7 on: 01/12/19 18:59 UTC »
The plastic you use has a lot to do with it, the plastic I’m using now (bait plastics bj200 medium) how I tested it was to make straight white and see how it did with multiple reheats. It was still bright white after the 6th reheat.

My heating is pretty similar to yours except that I do 30 second intervals on the initial heat because I was given a microwave to use and it’s a 1450 watt, otherwise I use 15-20 seconds on reheats. The only color I have had problems with is junebug, which is notoriously bad about darkening on reheats (at least lureworks colorant in junebug).

I also use heat stabilizer on all of my plastic, from raw.

Offline BareKnuckleJigs

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Re: Preventing yellowing of plastisol
« Reply #8 on: 01/12/19 19:26 UTC »
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Offline Jake Hendrickson

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Re: Preventing yellowing of plastisol
« Reply #9 on: 01/14/19 07:21 UTC »
i am using the essential series plastisol.

Tom, thank you for the indepth response.  for white specifically, i do have the X2 and the smaller Do it bottle of white that I will have to experiment with.  I bought some kinetic sand and a small 8x8 electric skillet this weekend and will be doing some temperature tests (with my thermometer  ;D)

thank you all for the responses!