There are a number of different kinds of silicone putty, though the most popular types tend to be two-part putty, all-purpose putty, and putties specially formulated for labs and food-related uses. The core characteristics of each tend to be pretty similar. Differences usually center around other ingredients and additives, and tend to be specific to the uses for which the putty was intended. Two-part putty, for instance, is commonly used to create molds for figurines and other crafts, and is designed to cure quickly and pull away from materials very easily; all-purpose putty, on the other hand, is generally used in home repairs and tends to be a lot better at binding things together and creating an air-tight seal. Lab and food grade options are among the purest, and are usually approved for use in medical scenarios and food manufacturing. Choosing the best putty for a given job is usually a matter of understanding the differences and having a firm sense of the desired goal.
In general, a silicone is any one of several varieties of complex polymer, which is to say, a chain of molecules bound tightly together. They are almost all synthesized in chemical labs, and have thousands of uses in industry. There are many different forms, though putties tend to be some of the easiest to work with and to access, particularly for people outside of scientific or research settings.
Putties are, as their name might suggest, pliable, flexible, clay-like materials that typically have a lot of elasticity and hold their shape well. Once set and cured, they also have some of the most desirable qualities of silicone generally: they withstand high temperatures, leave no residue, and are both odorless and tasteless, for example.
Two-part silicone mold putty is the option most commonly found in craft stores and general merchandise shops, and it’s typically used to create simple models. Such models are reusable and flexible, and can withstand temperatures of up to 600° F (about 316° C). Designers looking to create small-scale versions of proposed layouts often choose this type of putty, and it’s also useful for making molds that different, firmer materials can be poured into. This type of putty can also be used with other materials to make miniatures, such as doll figurines and doll house furniture. Two-part putty does not typically require very much time or skill, and is often considered ideal for amateur model makers.
All-purpose putty is more commonly used around the house and in construction repair projects. It is popular for filling and patching PVC pipes, for instance, and can also be used for ceramic, tile, and laminate. In larger quantities it can be used to patch driveways, walls, broken chimneys, knot holes in wood floors or ceilings, cracked shingles, and more. This putty sets quickly and typically forms an airtight, watertight seal, and is often easier to work with and shape than comparable silicone products like caulking or spray.
Silicone lab putty is used in medical and dental settings, usually in casting and impression-making. It is sterile and non-toxic, so it’s safe if it comes into contact with internal membranes or sensitive areas of the body like the skin. In dentistry, patients are often asked to bite into trays of putty at room temperature, which is then allowed to harden to create an accurate model of the mouth and tooth alignment. This allows dentists and orthodontists to create accurate devices and to properly plan for tooth repair, including the creation of things like crowns, dentures, and porcelain veneers.
Less commonly, castings can also be made of hands, feet, and even faces, which can assist surgeons and other medical professionals in making prosthetics and planning reconstructive procedures. Using putty is often faster and, importantly in many contexts, cleaner than other options. It doesn’t usually leave any residue or chalking.
Food-grade silicone putty is similar to two-part silicone putty, though it tends to be purer and will usually also set faster — often in as little as 15 minutes. It’s used almost exclusively for food molds. Once the mold is made, set, and cured, which usually requires baking at high temperatures, it can be used with butter, chocolate, edible cake decorations, and more. It can also be used to make hard candy or caramels.
Putties are widely available for purchase in most places. Two-part and food-grade silicone putty are most often found at local craft store or online, and all-purpose putty can be found at most home improvement stores. Medical and lab-grade putties can be harder to come by and usually require a connection to a medical supply distributor. Sometimes they can be found online, though as is true for anything bought over the Internet, purchasers should be sure to verify the quality and origins before using a product in a medical or other lab setting.