Theraputty is primarily made of silicone polymer mixed with boric acid, fumed silica, and several other ingredients that together create its distinctive squeezable, resistive texture. The exact formula varies by resistance level, but the base is the same type of silicone compound found in products like Silly Putty, engineered to provide consistent resistance for hand and finger exercises.
The Core Ingredients
The foundation of therapeutic putty is a silicone polymer called hydroxy-terminated polymethylsiloxane. This is a fluid silicone that, on its own, behaves more like a thick oil than a solid. It typically makes up 50% to 80% of the putty by weight and gives the material its smooth, pliable feel.
Boric acid is the second key ingredient, usually comprising 10% to 20% of the formula. When boric acid reacts with the silicone polymer, it creates cross-links between the polymer chains. This is what transforms the silicone from a viscous liquid into a semi-solid putty that holds its shape but yields when you squeeze it. Without boric acid, you’d just have a handful of silicone goo.
Fumed silica, a fine powder form of silicon dioxide, acts as a filler and thickener. It typically makes up 5% to 15% of the putty and plays a major role in determining how firm the final product feels. Higher concentrations of fumed silica produce a stiffer, more resistant putty.
What Controls the Resistance Level
Theraputty comes in several color-coded resistance levels, from extra-soft (tan) to extra-firm (black). The difference between these levels comes down to the ratio of ingredients and, in some formulations, the addition of modeling clay. Modeling clay used in therapeutic putty is a blend of kaolin (a fine white clay), sulfur, lanolin, and glycerol. By mixing different proportions of the silicone-based putty with this clay mixture, manufacturers can fine-tune the firmness.
The silicone polymer itself also comes in different viscosities, ranging from thin and flowing to thick and sluggish. Using a higher-viscosity silicone base produces a firmer starting putty before any clay is even added. So the final resistance you feel is the result of multiple variables working together: silicone viscosity, filler concentration, and the proportion of clay blended in.
Minor Ingredients and Their Roles
Several smaller ingredients round out the formula. Glycerin, at roughly 2% to 4%, acts as a plasticizer that keeps the putty from drying out and helps it maintain a smooth consistency over time. Mineral oil serves as a “detackifying” agent, typically at 1% to 10%, preventing the putty from sticking to your hands or surfaces. Oleic acid, a fatty acid also found in olive oil, further reduces stickiness and improves the putty’s workability, usually present at 1.5% to 5%.
These minor components are what make Theraputty pleasant to handle. Without the mineral oil and oleic acid, the silicone-boric acid mixture would leave residue on your skin and cling to tables and clothing.
Allergen and Safety Profile
Theraputty is free of latex, gluten, and casein, which makes it safe for people with those common allergies. The silicone base is chemically inert and does not trigger latex sensitivities the way rubber-based exercise products can. The manufacturer recommends washing your hands after use, particularly before eating, but no respiratory protection or special handling is required. The product does not have a defined shelf life, though it can dry out or lose its consistency over time if left uncovered.
How It Compares to Silly Putty
If Theraputty’s ingredient list sounds familiar, that’s because it shares its chemical DNA with Silly Putty. Both are built on the same silicone-boric acid reaction. The difference is in the engineering. Silly Putty is designed to bounce and stretch as a novelty toy, while Theraputty is formulated with carefully controlled filler ratios and clay blends to produce specific, consistent resistance levels suitable for rehabilitation. The addition of modeling clay, adjusted silicone viscosities, and precise filler amounts are what separate a therapeutic tool from a desk toy.