Author Topic: Dual injection frustration  (Read 523 times)

Offline superharmonix

  • Lunker
  • *****
  • Posts: 868
Re: Dual injection frustration
« Reply #15 on: 01/06/19 23:11 UTC »
I am looking at your pics....Your problem here does not have anything to do with your mold gates....  This is a viscosity issue.  Hopefully you are using accurate thermometers.  (probe style, not point and shoot style).

Colorant will act the same as softener which will speed(thin) the viscosity.  So when shooting lams, if you have exactly the same amount of colorant in each color, the viscosity will be the same, so shooting within about 10 degrees of each other will produce a 50/50 lam.  If one color has more colorant, the viscosity will be thinner(faster) in that color, so the thicker(slower) viscosity color will need to be hotter than the other to get a perfect lam because it will flow slower.  This is not a perfect science, as there are many variables.  i.e....If you use a lot of powder in one color and not the other it will slow the viscosity too.

I would bet you have more colorant in the darker color here.  Try it again with the darker color hotter than the lighter color. 

Offline Thembonez

  • Keeper
  • ***
  • Posts: 83
Re: Dual injection frustration
« Reply #16 on: 01/07/19 09:57 UTC »
I am looking at your pics....Your problem here does not have anything to do with your mold gates....  This is a viscosity issue.  Hopefully you are using accurate thermometers.  (probe style, not point and shoot style).

Colorant will act the same as softener which will speed(thin) the viscosity.  So when shooting lams, if you have exactly the same amount of colorant in each color, the viscosity will be the same, so shooting within about 10 degrees of each other will produce a 50/50 lam.  If one color has more colorant, the viscosity will be thinner(faster) in that color, so the thicker(slower) viscosity color will need to be hotter than the other to get a perfect lam because it will flow slower.  This is not a perfect science, as there are many variables.  i.e....If you use a lot of powder in one color and not the other it will slow the viscosity too.

I would bet you have more colorant in the darker color here.  Try it again with the darker color hotter than the lighter color.


I’ll say this, and it has been stated here already. If this is the case white will be a bear to do laminates with! That white colorant really thickens up the plastisol(in my opinion) going forward I’m about done with my second presto pot and stirer (both PID heat controlled) so I’ll be able to dial in a temp and hold it. That’ll make my life a lot easier then, I should hope!

Offline Thembonez

  • Keeper
  • ***
  • Posts: 83
Re: Dual injection frustration
« Reply #17 on: 01/07/19 10:03 UTC »
I wonder what the purpose of that cutout is? Pretty sure it’s a standard injection port. If its important to lam this bait and your sure that the cutout/restriction is causing your problem, it can probably be removed. Clamp the two halves together with c clamps and with a 5/8 inch bit on a drill press looks like you could cut it out. Not sure why it’s there? Maybe it was the designers way of creating extra plastic to draw from as the bait cooled. Unnecessary in my opinion. Just a longer straight runner will do the same.

Not sure the reasoning behind the “ball” chamber, but it makes shooting core shots a breeze on a few other molds. Open pour that chamber and shoot. It’s almost as if it’s pre measured for this method. Haven’t tried it on these select molds yet.