Why did my blue ice turn green?

[sim]

So - followed this recipe -

4oz plastic
2 drops of x2 blue
1/16 tsp of pearl (after hot)
1/8 tsp of blue flake (.40)
1/8 tsp of black flake (.15)

First runs looked GOOD - almost exactly what I wanted.

As I ran down on plastic (when I could make no more DD Gills or get a good pull on the injector without air) - I put all the sprues and plunger nubs back in the pirex - added 6 drops of heat stabilizer and nuked for about a minute - long enough to get it back to temp with no lumps.

next pours had a serious  green tinit where it used to be blue.

Not bad, mind you - I kinda like the color - might even be a better 'color' for sunfish then the stronger blue - but what happened?

[ctom]

Your plastic got too hot the second heating. Next time just heat the trim for 30 seconds, give it a stir and check the temp. Heat no more than 15 seconds at a pop after the 30 second heating and check that temp after each shot in the MV and be darned sure to check the temp. You have to stir, then check the temp. This plastic is notorious for scorching on re-heats and re-melts if you do not heat the stuff up slowly and in short bursts in the oven. And try 15 to 20 drops of the stabilizer and be certain to mix it in well as you heat.

This is a common thing when you're getting used to things. Not to worry, you figure it out.

[Denny Welch]

I'm thinking you may have burned it.  Depending how much you were reheating, a minute can be a long time without a good stir and a temperature check.  Don't forget you don't have to bring it back to 350 degrees.

[Denny Welch]

OK, OK...got beat my Tom again.

[sim]

ok - I think I have seen 370 on my themometer a couple of times when doing this 're-melt' - I did stir at 30 (lots of lumps left) then let it finish for the other 30 - nice and liquidy.

Ok - I'll go 30 - 15 next time.

I realize I didnt hvae to get it to 350 - but was just trying to delumpify it -

Is it ok to reheat in the microwave in 15-30 second bursts between molds? it'll never stay 320-350 long enough to get more than 2 done (and thats if I demold 'fast') at a time.

[kipbass]

After it hits 350 degrees the first time, it doesn't have to be that hot anymore. Unless, you add fresh plastic to it. I think some glitters may affect the way it heats too.

[Denny Welch]

That's one of the drawbacks to using a microwave, sim.  You either start with less plastic or purchase more molds.  Another alternative is keeping your plastic hotter for a longer period of time.  You can do this by using a presto pot, or a cast iron pot, or maybe making a POP mold to hold your pouring cup so it doesn't lose heat.  Each has it's own benefits and drawbacks.  You might want to use the "search" feature on the forum for more information.  Good luck.

[sim]

how about buying a 'griddle' or 'hot plate' and setting the cups on it?

Other than 'one more thing' to keep clean (and my elbows off of, and hey, don't set the bait there) seems it could keep the cup o' plastic at the right temp.

[ctom]

Sim you metion getting the plastic smooth on re-melts and having lumps in the product. That's normal until the plastic reaches that magic temperature and the lumps thin out. Keep in mind that hard or firm plastic will handle different from soft or medium on re-heats and plastics from one company could well behave different from plastics coming from a different source.

As a rule, you won't have to hit 350 to get a re-melt smooth, unless you are adding a splash of raw plastic to help spread things out. Any raw plastic will have to be brought up to 350 regardless of if the scrap in with it has already been that hot. IF you add raw plastic to help in a re-melt, load the raw plastic with stabilizer and stir it in good BEFORE you add the scrap to heat. By load it up with stabilizer I mean like 25 to 30 drops in a 4 ounce raw plastic batch to which you add scrap. The stabilizer will cook out with subsequent heatings but it also protects the new and the old plastic at the same time. Make stabilizer an good friend, you'll be in the winning column a lot sooner if you do.

Go back thru the reading materials about a year....I posted pics of an electric skillet which has been sand-bedded to hold smaller cups of liquid plastic that I use when I am working with multiple colors. The sand is formed around and under the cups so that when the heat is on the sand heats up and spreads the heat very evenly. I bought the skillet on the third day of an estate sale for 50 cents and it works like a charm. I'll see if I can find the pic I posted and put it up here again. 

[ctom]

Here Sim....I ran out and took a quick pic of the skillet with the sand bed in it. You'll get the idea.



I left one cup empty so you can see the sand under the cup. The sand is about 1/2" thick under each cup and the cups are pyrex ramikins or custrad cups each with a volumn of about 7 ounces. They work great for the smaller batches I shoot.

[sim]

thanks - neat idea on the skillet.

I am only using Caney Creek plastic - my remelts have only been the plastic I was already working with.

I thought stabilizer only needed to be added to re-melts - or should I be adding it to the raw plastic as well?

So much to learn - and the wife just put in an order for more of the 'green' mistake bait!

[Brent]

your reheat time will depend on the wattage of the microwave, I had a 1200 watt and it was touchy between just right and too much on reheats, I picked up a 800watt on Freecycle.org and now everything works like clock work, I can shoot, de-mold, drop the sprues back in, couple drops of stabilizer and hit 20 seconds, get the mold lined up, resent injector, pull cup out stir, hit 12 seconds, clamp molds, pull cup out, stir and Im ready to inject again.

Im not saying this is the way to go but it works for me.

[ctom]

"I thought stabilizer only needed to be added to re-melts - or should I be adding it to the raw plastic as well?"

Any white, clear or very light color you you make will be more susceptible to burning or yellowing if you don't add stabilizer from the get-go. Even blues and reds need to get a little add since they can chance color directions in a heart beat. As you get more confident in your working with this plastic stuff you'll be able to down shift a bit and know when to add stabilizer and whehn you want to juice a color up with it. You'll get more in tune to heating times for different colors too and the more specific you become with heating the less you'll lean on stabilizer. I'd lean on it though until you've learned all of the ins and outs of the plastic and heating it.

[sim]

Thanks - on average, how many drops per 4oz plastic?

[ctom]

The lighter or clearer the color, the more I add. Generally in my 4oz batches between 20 and 30 drops. 30 drops going into clear plastic with some glitter/hi lite. I'll note here that glitter can create a lot of heat and if a color is heavy on glitter and changing you may want to cut  back on the glitter a hair to control the heat.