tunnel porosity

[Mhgjewel]

im currently using a 50/50 b9 cherry / b9 green mix with premier optima investment. they surface turns out beautiful but on closer inspection there might be a tiny pit and when i go to repair it with the laser it ends up being a tunnel or pocket under the surface. we double vacuum the inside the flask out to get rid of any left over ash that might be in there. any thoughts?

[Devlin]

I just cast two heavy Mens rings in silver. I found a few pockets, my assumption on my casting is either flux in the metal or insufficient spruing.
This was a cherry resin casting, I am fusing metal in with a torch to fill the holes. This in general has not been a problem in the past.

[Jewelermdt]

I think is't more like Devlin said, I get that casting wax sometimes. Metal too hot, turbulence from the design, no feeders to thinner parts.

[rsaldivar]

I think longer hold times at top temp and vacuuming at top temp in stead of blowing air . but thats just my 2 cents worth , I haven't tried that

[M-Williams]

im currently using a 50/50 b9 cherry / b9 green mix with premier optima investment. they surface turns out beautiful but on closer inspection there might be a tiny pit and when i go to repair it with the laser it ends up being a tunnel or pocket under the surface. we double vacuum the inside the flask out to get rid of any left over ash that might be in there. any thoughts?

Why d'ont you just use cherry only. just shake it well. It casts great.

[WadeWebb]

I even don't have a clue on how to solve such an issue! Have you contacted someone else with this question?

[Archerm]

Whenever you get a thinner area transition into a heavier area( more Mass) this will happen if the part is not sprued properly. Always have your main sprue attached to the heaviest spot on the model. Even with mens rings I design them where the shank has the most mass and the top has the mass spread out. The thinner areas will always cool down first and the the heaviest. If not sprued properly the heavy and lighter areas will try to rip apart leaving porosity. The ideal scenario is the top of the ring cools first, then the shank, then the sprue, then the button in that order. Try to design your pieces so this happens.

[ErickNorthman]

Whenever you get a thinner area transition into a heavier area( more Mass) this will happen if the part is not sprued properly. Always have your main sprue attached to the heaviest spot on the model. help with writing a dissertation literature review

[Jewelermdt]

I just had two rings do this. I had sprus running up to the top of the ring in two places. Was a split shank at top with stones set into it. I figured it was because of the seats Boolean out through the shank. Redesigned ring without, still had tunnels. This was a thicker ring, 3.2mm stones. I cured the heck out of it and also let the flask set for 10 hours before burning out. Got a good cast. I was casting yellow gold using customers gold with a little new added. I get this problem more with yellow than white for some reason.