Hello Dave,

I use Hydrostone as well, and after trying many different ratios, I finally settled on 2.8 grams of Hydrostone per 1 ml of water. The ratio you are using is 3.2 grams per 1 ml water, which will make your mixture a little thicker than I use. You can either weigh the water or measure it by ml because 1 ml water weighs 1 gram. I have found it was easier to measure the water instead of weighing it. You may find this ratio works well for you, I just wanted to let you know what I have experienced. image

I use a chart I created that shows how much Hyrostone for each 10 ml of water.

For example,

40 ml water - 112 grams Hydrostone
50 ml water - 140 grams Hydrostone
60 ml water - 168 grams Hydrostone

I measure the water and weigh the Hydrostone and after mixing, I pour into the mold while it is on the vibrating table (from Bruce's instructions). About half way through pouring, I will stop briefly to stir the mixture again, as it tends to settle a little bit. So far this method has produced very few bubbles. My typical demold time is about 24 minutes, which is 6 minutes then scrape and demold after 18 minutes more. Hope this helps.