girl face melt

Sex doll manufacturers are on the hunt for skin. It’s what binds doll parts together, makes the user feel like they’re touching a pliant and agreeable woman, and keeps a doll’s body fresh through years of wear and tear. It has to look like skin, feel like skin, and not pull apart or melt when exposed to water. No company has discovered a perfect skin simulation yet, but they’re close.

Though sex robots and dolls are becoming increasingly popular, no single material can replicate the texture of human skin while withstanding friction and heat over time. A company called Hanson Robotics developed and patented “frubber”, or flesh rubber, which has excited the sex doll fan community, but most dolls are still made of silicone or thermoplastic elastomer (which fans call TPE), a blend of silicone and polyvinyl chloride.

According to the sex doll fansite MySiliconeLoveDoll.com, the pros and cons of each material are as follows:

TPE skin is more realistic

TPE is more affordable

TPE is softer

TPE is more flexible, allows easier handling of doll

Silicone is more sticky than TPE, it feels like modeling clay, but can be fixed with baby powder

Silicone dolls can take a hot bath, TPE dolls should not

Sex doll collectors and consumers discuss the merits of both materials online, at length, and even go so far as to DIY hack their own dolls with TPE or silicone patches, but it doesn’t appear that distributors are listening yet.

In fact, the sex doll community online is so insular that users don’t even tend to debate the ethics of owning a synthetic woman for the purpose of masturbation. On public posts to The Doll Forum, a discussion board for sex doll collectors and enthusiasts, most users typically share innovations in manufacturing. On the topic of skin and realism, one user, Campion, says, “Hanson claimed to be using a material called “frubber” which appeared to be super-soft and elastic. It looked like some sort of TPE formula, actually. Realbotix doesn’t seem to have such faces high on its priority list, sadly.” The thread then delves into the discussion of how high quality, synthetic skin can actually hide a less-than-ideal robotic structure underneath. There’s also eye movement and placement to consider, and which skin material will be able to move fluidly along with robotic features, once sex robots that can simulate emotions are on the market.

In other corners of The Doll Forum, users debate whether innovative materials like Frubber will prove useful for the “center of activity” (a doll’s synthetic genitals) in addition to a doll’s face. Just as in the human body, synthetic skin on a doll needs to have different thickness, texture, and elasticity on different parts of its body. A face, for instance, will ideally stretch around the sex robot’s internal skeleton when it needs to emote. The synthetic skin making up a doll’s false vagina, on the other hand, needs to respond well to friction and has to be able to incorporate moisture and heat without melting.

Though skin simulations are at the center of sex doll manufacturing, many users are simply trying to make their own silicone-like figures using homemade molds. Any repairs to the expensive dolls are often done at home, and doll owners discuss their systems with each other. The first question many ask in a discussion thread regarding repairs to a doll is: silicone or TPE?

sex doll lips
A TPE sex doll's "lips" begin to peel after vigorous use.

Silicone dolls can be cleaned in the bath using anti-bacterial soap, and they need to drip-dry and be powdered rather than using a heated blow dryer. Similarly, TPE dolls have low melting points, which makes blow-drying their hair, or using heat to solidify any makeup, a difficult and delicate process.

No matter what a doll is made of, details tend to rub off when exposed to friction, as evidence in this post about a doll’s make-up flaking off over time. Another downside of TPE seems to be, given how many posts appear on the boards about it, that it easily retains stains.

Though no other industries may care so much about the TPE vs silicone “skin” debate, innovations in other fields may lead sex doll owners to a new frontier. Hydrogel, for instance, is a “slippery, soft” material being developed for use in condoms, and electronic “skin” with sensors is gaining popularity in the robotics industry.

In late 2016, robotics expert David Levy predicted that sex robotics with the ability to speak, and genitals that warm and moisten themselves in response to touch, would be on the market by 2017. Levy didn’t specify which skin design these sex robots would likely use, and his prediction has only four months to come true in time. For sex doll enthusiasts, the debate is still raging between TPE and silicone, and they haven’t even begun to test the merits of some of the industry’s newest materials.

See also: This European Charity Suggests Giving Childlike Sex Dolls to Pedophiles