has anyone here used pressurized air OR a vacuum when casting concrete into a mold? Asking for a friend.
More typical is to use vibration to help settle the concrete into corners, etc. A palm sander can be used for smaller parts. Leave the sandpaper off and press the rubber platten to the sides of the mold.
Hirst Arts mold casters (small plaster molds usually used for making wargaming/RPG terrain pieces) use this technique. You can set up a vibrating table (rubber blocks or springs attached to the underside of a board) and use the palm sander on the table to in turn vibrate the mold.
4 Likes
thanks good idea, do we have that kind of sander at DMS?
I’m space/time challenged so I do the same too but generally just move it around the mother since our molds are small. Resin inclusions is pretty much the only time I bust out the pressure pot…because best practice as practical aren’t always friends lol 
(Insert suitably bawdy joke about vibrators and here since I can’t be the only one thinking it)
I used a palm sander to vibrate a few tables I made and it worked well. I did have to repair a few pits but probably would have with a stick vibrator as well.