All of the following are characteristics of odorless acrylic products EXCEPT?

The correct choice accurately highlights that odorless acrylic products do not harden quickly. Odorless acrylic products are formulated to have a lower volatility, which means they emit fewer vapors than traditional acrylics. This formulation results in a slower curing process, allowing for more working time during application.

In contrast, the other characteristics present in the choices reflect typical features of odorless acrylics. The slight smell refers to the minimal odor that still exists in these products compared to their traditional counterparts, contributing to a more pleasant working environment. The top tacky layer is characteristic of many acrylic applications, allowing for better adhesion when additional layers or products need to be applied. Lastly, a dryer mix ratio typically indicates that less liquid is used in relation to the dry product, which can affect the product's viscosity and application but is not directly linked to the hardening speed of odorless acrylic.

Understanding these characteristics helps nail technicians select the right products for their clients and manage expectations around application and curing times.