Been casting with resin for years with no problems, however I have one class ring that is giving me trouble. I am running into an issue that is causing the letters and number to fill with metal during casting. I have run out of ideas on what to try and I was wondering if anyone might have a solution? The issue that is happening is the recessed area between the letters and the walls are filling up with metal (distance between letters and walls are 1mm - 2mm). I’m not sure if it’s the resin expanding during burnout process (I don’t think so because the ramp up time is quite slow) or if its a form of erosion? The only reason I’m skeptical on erosion is because I haven’t seen any inclusions of investment.
The investment I am using is plasticast with a 40ml/100g mix. This is the same ratio I use on all our items but this one class ring still comes out with defects. The oven times are 300F for 2hrs, 700F for 1hr, 1350F for 2hrs, and then 1hr soak time at casting temp and the flasks are 2x3 or 3x3.
I have tried various ideas, such as how many flasks are in the oven at once (no change), + / - water ratio (no change), sprue placement (no change) and how long the flasks set in the oven. Even though the ring still did not come out, the closest the ring has come to a perfect cast is when I left the flasks in the oven longer than normal. Which has me believing that maybe the investment isn’t curing or hardening enough? But the only issue with that is I’ll have other rings the same size, with similar detail, in the same oven that will come out fine. On average the flask sit out for about 6 hours before they are put in the oven for the night.
I have tried using centrifugal force casting and vacuum casting, both result in the same issue.
Any advice would be much appreciated.