Silicone is usually available as a waterproof caulking or gasket material, but has some uses as a glue for applications where flexible waterproof sealing is required against difficult to glue surfaces like smooth glass, ceramic and metals. As silcone is a thick bodied material which holds its shape, it is often used with miniatures and models where separation of pieces, or flexible bonds are useful. (holding motors into model planes for example). Silicone caulk is also used by some modellers to create the effect of flowing water in model terrains.
Silicone has several uses for miniatures, as a glue, a modelling material for modelling running water, and for gaskets. Although it is not usually considered an adhesive, it is sometimes sold as one for special purposes. A number of brands of 'silicone glue' are are available from craft stores, mainly for setting up thick layers for scrapbook and card details. Silicone glue is often recommended as a spacer for metallic papers, like the metallic decoupage flower fairies and papers from Dufex as well as other thin metal sheets and decorations from scrapbooking stores. It is readily available from hardware stores (small tubes of silicone glue or caulking), most craft stores, marine and automotive suppliers, where it is sold in small tubes for fast gaskets, as well as glass and aquarium suppliers, where it is used to glue and seal the sides of aquariums. As silicone is very flexible, as well as resistant to water, uv light, and heat (up to 600 degrees F.), it makes a good bonding agent for glass (aquariums and angled dollhouse windows), metals, small engines and other materials where bonds need to withstand water, or remain flexible in order to hold. While different formulations of silicone have a few different properties; cure time, type of cure, flexibility, color, and paintability, most are interchangeable for the purpose of making miniatures.
Silicone is often used by scenic modellers of railroads and gaming terrains to create flowing water effects for rivers and streams. Although it can be used for these purposes, it tends to collect dust as it never fully hardens. There are better products to mimic water effects on terrains, including clear tar gel and other Acrylic Artist's Mediums
Important Note: - Silicone adhesives are available with and without acetic acid. Avoid the ones containing acetic acid whenever possible, as the acid creates problems with miniatures made of paper, metal, or wood. Silicons which use a moisture vapor cure system release acetic acid as they cure. These types can cause metal corrosion. See the information on Why Use Acid Free Materials to understand why you should avoid silicones that release acetic acid as they cure. The smell of the glue / caulking will be a lot like vinegar if you are using a silicone glue which contains acetic acid. Odorless cure caulks do not have acetic acid but cure with an 'oxime' curing agent.
Bonds with silicone adhesive are not particularly strong and can easily be peeled out. The silicone often remains slightly tacky, which means it will gather dust. If you wish to paint over a silicone caulk you must use a paintable version of the caulk in the first place. For miniatures, small applicator tubes of silicone are preferable to building or bathroom caulk, as the bead can be more easily controlled, and there is less waste.
Layers of silicone caulk or adhesive should be less than 1/4 inch thick, as the silicone adhesives need moisture in the air to cure. You can use silicone caulk or adhesive to make simple moulds, similar to using two part silicone mold putty. The caulk needs to be applied in thin brushed on layers allowed to dry between coats, and it should be supported with a hard outer mold shell, similar to brush on latex molds. The caulks do not have quite the tear strength of the mold putty, take longer to cure and don't hold detail quite as well, but if you are stuck, you can make simple molds this way, although you should use a mold release on your object (green soap, or an oil cooking spray both work).