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Preventing bubbles in sterling silver lost wax castings

I teach Lost Wax Casting in my High School Jewelry classes, and we have a high success rate. The one flaw we consistently have is “bubbles” which sometimes form in recessed areas of the casting. These are later removable with ball burs (in silver), but you can usually detect where that happened. Do you recommend a solution or treatment to the wax model before casting in order to prevent such “bubbles” from adhering? Thank you!


  1. debubblizer coating your trees prior to investing. I use pro-coat vac-u-coat spray, which is a proprietary isopropyl alcohol. You need a well ventilated area. It can be invested wet or dry on a tree.
  2. Pay close attention to the orientation of wax pieces to be cast on the tree. Design the sprues to allow for best flow of metal into the individual piece without turbulence AND so that the pieces don’t trap air pockets underneath overhangs while the tree is vacuumedthe piece. Examine where the bubbles are happening in relation to their orientation when vacuuming and investing.
  3. vacuum the investment after its been thoroughly mixed and and after its poured into the flask.
    Of course, it’s all three that can best eliminate any bubble issues. No amount of debubblizer will make up for a tree with components that are designed with inherent air traps & overhangs.
    Good luck!!
    EileenSent from Yahoo Mail on Android
1 Like

Thank you Eileen - these are super helpful. Do you have a particular debubblizer you prefer?

Wendy, Glad to be of help! I mentioned the pro-coat vac-u-coat spray. It’s a bit stinky, but it works well. Eileen