I vacuum de-gas all my silicone molds, and then use a pressure pot for casting into it. You want to get the vacuum down to around 28 inches of mercury. How long it takes depends on how thick the silicone is, how much air you've whipped into it in the mixing process, and the cure time of the silicone. (Some cure too fast to de-gas.) I prefer de-gassing in a cup or bucket before pouring it into the mold.
I've had problems with pressure casting into a mold that hasn't been de-gassed. The pressure causes all the trapped air bubbles in the mold to shrink which can mildly distort the entire mold. Also, if there is a bubble in the mold right next to the part; when the bubble shrinks, it creates a bump or pimple on the casting.
I'm not familiar with the Pinky silicone that you are using, but I find that platinum silicones are more expensive and fussier to use than tin silicones, so I only use them for particular needs. (For instance; clear casting resins seem to prefer platinum silicones.)
As for temperature - Yup! cold weather slows or stops the cure process. I've brought molds into the house to cure on cold nights (you just want to be sure nothing leaks!).
On some occasions I've made a "hot box" in my shop by putting a cardboard box over the mold with a 75 watt desk lamp shining into it to keep it warm inside. Just be careful that any hot parts of the lamp aren't touching the box (…fire, bad…).
I've had problems with pressure casting into a mold that hasn't been de-gassed. The pressure causes all the trapped air bubbles in the mold to shrink which can mildly distort the entire mold. Also, if there is a bubble in the mold right next to the part; when the bubble shrinks, it creates a bump or pimple on the casting.
I'm not familiar with the Pinky silicone that you are using, but I find that platinum silicones are more expensive and fussier to use than tin silicones, so I only use them for particular needs. (For instance; clear casting resins seem to prefer platinum silicones.)
As for temperature - Yup! cold weather slows or stops the cure process. I've brought molds into the house to cure on cold nights (you just want to be sure nothing leaks!).
On some occasions I've made a "hot box" in my shop by putting a cardboard box over the mold with a 75 watt desk lamp shining into it to keep it warm inside. Just be careful that any hot parts of the lamp aren't touching the box (…fire, bad…).
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