PlatSil® Gel-OO20 and RTV-4020 are both ultra-soft Shore OO20 platinum-cure silicones, placing them in a category that differs substantially from conventional Shore A mold silicones. At this hardness, the material is intended to provide very high flexibility and deformation rather than strong structural support. This profile is relevant to applications where substantial stretching and soft cured behavior are required.
Both systems use a 1:1 mixing ratio, so component proportioning is not a major distinction between them. Polytek specifies 1A:1B by weight or volume for Gel-OO20, while RTV-4020 also uses a 1:1 system. Their published working windows are broadly similar, at approximately 40 minutes for Gel-OO20 and 30–40 minutes for RTV-4020.
Viscosity is somewhat different in the published specifications. Polytek reports 3,900 cP for mixed Gel-OO20, while MinghuiLink reports approximately 2,200±200 mPa·s for Part A of RTV-4020. Because these values are reported at different measurement points and material states, they should not be treated as a direct viscosity ranking. The published data nevertheless indicate different processing characteristics that should be considered when mixing, pouring and managing air.
The more noticeable processing difference is demolding or cure time. Polytek lists approximately 2 hours for demolding Gel-OO20, while MinghuiLink lists approximately 4–5 hours for RTV-4020. Their published definitions are not identical, so the figures should be treated as manufacturer-stated processing references rather than a direct cure-rate comparison. For workflows where earlier demolding is important, the shorter published demolding time of Gel-OO20 may be advantageous.
The largest published mechanical difference is elongation. Gel-OO20 reports 964% elongation, compared with 560±50% for RTV-4020. This substantial difference may be relevant when the cured silicone needs to undergo significant stretching around irregular shapes or during demolding. Tensile strength and tear strength are reported at different levels and using different test methods, so those values should be treated as manufacturer-published reference data rather than directly ranked.
Surface characteristics provide another practical consideration. MinghuiLink notes that the softest grades in its life-casting series, including RTV-4020, may have slight surface tack after curing and recommends a light application of talcum or baby powder to reduce the tack. Gel-OO20 is positioned by Polytek for soft, flexible applications including prosthetics, masks, animatronics and medical models. Final selection should therefore consider elongation, demolding time, surface feel, finishing requirements and the intended fabrication workflow.
