Silicone rubber has many properties which are ideal when coating metal tools and other objects. It can greatly improve your tactile grip, reducing the risk of dropped tools. Because it is a poor thermal and electrical conductor, it is very useful in protecting you from hot or electrified surfaces. Coating metal in silicone is not complicated, but it does require a few steps in advance to ensure a good bond.
Score the metal surface that you wish to cover with a grinder, metal file or other tool. The scratches that you add will give the silicone rubber areas to grab onto.
Pour a batch of fast-curing silicone base into a bowl. You must be able to submerge the metal that you want to cover. If the silicone is mixed with its catalyst by weight (as opposed to mixing by volume), you must subtract the weight of the empty bowl from the total weight to deduce the weight of the silicone.
Mix catalyst into the silicone base, following the mix ratios on the container. Most silicones have either a 10:1 or 1:1 ratio of by weight or volume.
Stir the silicone base and catalyst thoroughly, making sure there are no unmixed areas. Scrape the sides and bottom of the bowl with the mixing stick several times.
Add a few drops of thixotropic agent to the mixed silicone to thicken it. This must also be mixed in thoroughly. Thickening the silicone greatly reduces drips while the silicone is curing.
Dip the scored portion of the metal into the thickened silicone, then pull it straight out. You should dip and remove the metal slowly to reduce the risk of trapping air bubbles against the metal.
Hang the metal from a clothesline to allow the silicone to cure (held in place with tape if needed). If you want to completely cover an object, you must dip the first half, let it cure then dip the second half in a fresh batch of silicone.
- Smooth-On: How to Make Molds and Castings
- "The Prop Builder's Molding & Casting Handbook"; Thurston James; 1989
- Place a sheet of newspaper under the hanging tool to catch any drips.