Dent In Durham Water Putty Mold

[Saugerman]

What besides venting, will cause denting in plastic baits? Have more than enough venting in this swimbait mold but still get dents. I have 2 of the same molds and both do the same . I try to inject at about 330 degrees and above is this to hot? I have 35 plus water putty molds with out this problem. Any suggestions?

Thanks

Ps would post a picture but have not been able in the past.

[ram3139]

I'm pretty new to pouring soft plastics so I'm not the most qualified to help, but I have a similar problem with one of my pop molds that I think should have plenty of venting as well.  It seems like as the plastic cools, it shrinks a bit and that causes the dent.  I haven't had a chance to try anything yet, but it seems like the pour/sprue area cools a bit faster and kind of "skins" over (if that makes any sense) and doesn't let the extra plastisol on the sprue area flow into the mold to make up for the shrinkage.  I'm going to try warming up the mold in the over before pouring to see of that changes anything, and probably make a new mold with a larger sprue reservoir.

 

None of that may make any sense or be correct at all, but I thought I'd post just in case.  If you figure out your issue, let us know what the fix was.

[IBHUFFY1]

Hold pressure on the injector for about 10 seconds after filling the cavity.

[Saugerman]

Thanks for the replies, I think I have solved the problem, I started shooting the mold at around 300 degrees, and that has helped a lot. I have not had to do this with any of the other water putty molds ,don't know why this one is that way, but if you run upon this problem, it may help.

[ipt]

the denting will occur from a narrow space above a wider space. the narrow part will cool off before the fat part, and when the fat part shrinks, it wont be able to suck plastic down thru the narrow part.