An example of something viscous is maple syrup.
It is the viscous or graisse disease.
The solid melts to a pale yellow liquid which on continued heating gradually darkens and becomes more viscous, the maximum viscosity occurring at 180°, the product being dark red in colour.
Before work begins the temperature is lowered sufficiently to render the glass viscous.
As the larva approaches maturity these vessels become gorged with a clear viscous fluid, which, upon being exposed to the air immediately hardens to a solid mass.