If you mix the silicone components carefully it is possible (possible does not mean likely) to prevent air bubbles from occurring. It is likely that you can mini mize the size and number, but you are not lfkely to prevent bubbles altogether. There is also an effective workaround for de-airing your silicone without invest ing in an expensive vacuum pump and vacuum chamber. You can eliminate air bubbles (or at least make them very, very small-almost invisible) by pressuriz ing the silicone instead of pulling a vacuum. You still need a pressure chamber to do it, but air compressors are far less expensive than vacuum pumps and you probably already have access to an air compressor.
Small vacuum/pressure chambers can be found rather easily online at little cost, and if you're dead-set on vacuum de-airing, for about
$18(£9.66) from Harbor Freight you can buy a CentraLPneumatic air-vac, a Venturi-type vacuum pump that uses air pressure to create enough vacuum to de-air your silicone in short order!
Your air compressor needs to generate at least 90 lbs. of pressure to pull 28.3 (71.9 em) inches of mercury at sea level. From the same ven dor you can also find a 2V2-gallon pressure paint tank that is great for pressure or vacuum for under $100 (£53.59). Problem solved. With a little more effort you can replace the opaque metal lid with a clear Plexiglas (3/4-1 inch thick or 2-2.5 em) replacement so you can see what's going on inside. Often, however, simply allowing the silicone to sit at room temperature until the air bubbles have risen to the surface and disappeared is all you need to do before pouring or injecting the silicone into the mold cavity provided the silicone is not fast-setting.
GEL-FILLED SILICONE APPLIANCES
If you've every held a silicone breast implant in your hand (pre-implantation), you know how soft and squishy they are, or can be. Squeeze your cheeks (gently) or feel your (or someone's) love handles ... that's the consistency and softness a gel-filled appliance (GFA) should have. The best GFAs are made with a gel that has a much firmer consistency than you'd find in a silicone breast implant or breast enhancement product.
GFAs are arguably the single most difficult type of prosthetic appliance to make by reason of the steps involved in merely casting the appliance into the mold. The sil-
. icone gel must fill something; it is a gel-filled appliance. The gel is one- component.
The other, a silicone envelope or capsule, must be created for the gel to fill. How is that accomplished? By using an encapsulator, which can (should) be silicone or a liquid-like vinyl cap material that will cure to a solid, flexible skin. Using an encapsulator other than silicone could cause the gel and the encapsulating enve lope not to bond well and to separate (since nothing sticks to silicone except other silicone), causing unwanted and largely unfixable problems with the appliance. As long as you don't try to add a platinum gel to a tin encapsulator, the silicones
. should cure and bond permanently to each other without a problem