Guys i have reading many of your posts about air buble problems when casting resin. I think I may have a solution without having to vaccume. I used to do a lot of concrete molds for counter tops and what we would do is make a vibrating table. The vibration causes any air to come to the top and escape the mold. Now these tables where quite large but with 1/24 25 scale you could use almost anything that vibrates, even some of your wifes or girl friends toys Hand sanders would most likely be best. Just a thought, trying to give back hope this helps someone out there.
Resin casting Tip?
Posted 15 January 2013 - 08:11 PM
Vibration might work but it might make it worse by breaking up the air bubbles as well. Concrete vibrators are a pretty high frequency vibrator, high enough that it stings to the touch. (Might be why the concrete guys call it a stinger!?!) An old water bed or bed vibrator (massager) might work, but are fairly low frequency, the ones I've seen use two motors with an offset weight at each end of the bed or table. Might be able to find one for free, they make quite a racket on a wood floor.
Posted 19 January 2013 - 09:07 AM
The one problem I see with this approach is the fairly short "pot life" of polyurethane resin. This is the reason why professional resin casters, such as Modelhaus, Missing Link Resin Castings, Scale Models by Chris and others who do resin casting as a professional business use pressure tanks, as they can pressurize a tank, with the uncured resin in the molds inserted, quickly enough to literally crush out small air bubbles by the pressure of several atmospheres before the resin starts to "kick". That said, it is very possible to "chase" small air bubbles out of little castings simply by pushing them out of small details by using a toothpick.
Posted 19 January 2013 - 09:15 AM
The vibration might help with some of the bubbles, but the main reason for pressure potting or vaccuming is the keep bubbles from staying in the undercuts. Areas where bubbles can be trapped. As long as a bubble has a clear path to the surface it's not an issue, but as soon as it gets trapped under the leg of a seated figure or say inside the fin of a fifties car with a deep undercut no amount of vibration will dislodge it.