I had an intricate sculpture, cast in 9999 fine gold.
To avoid warping, I waited until the button stopped glowing (in a dark room) before plunging the cylinder in water. Most of the investment bubbled off in the bucket, but there was quite a bit, in very thick chunks (an inch in diameter or more) stuck in the more intricate sections of the sculpture.
After an hour in the ultrasound bath with Blast Off Investment Remover, it was clear that ultrasound wasn’t going to cut it for the thicker areas.
I tried a dental Water Pik, and also an electric toothbrush, but the going was very slow. It was very hard to reach some of the thicker chunks, especially with the toothbrush. And the Water Pik went through water so quickly, and is very difficult to control (there’s no “trigger” to turn the spray on… just a temporary stop button that gets stuck if you use it).
After another half hour in the ultrasound, still with very little progress, I decided to go outside with an Electric Textile Spot-Cleaning gun (which I knew would make a mess, so that’s why I tried other things first).
And boy, did it work. After about 5 minutes, all the investment was gone, and it didn’t damage the delicate areas of the sculpture, as far as I could tell. And it still had half a tank of water by the time I was done. It was also very easy to control, with a trigger to spray here and there as needed.
It did splatter little white droplets all over me (I wore safety goggles) and left a big white puddle in the driveway.
Of course, it hurts if you get your hand in the way of the stream, but it’s quite a bit finer, and more powerful, than a dental Water Pik.
This is the model that I have:
So I guess this is the way to do it, at least if you don’t wan to invest thousands in a special investment removal booth.
Now it’s back in the ultrasound for another 15 minutes to clear off any tiny bits that I might have missed (but visual inspection didn’t show any).