The fuzzy stuff in your gas fireplace is decorative rock wool that is used on vented gas logs or to replace wool on direct vent gas fireplaces.
The rock wool is a fibrous material that is made from minerals and when placed on top of the sand in a natural gas log set the fire passes through it and becomes red hot and glows without melting or burning.
The black stuff in your gas fireplace is soot which is the accumulation of carbon particles when the fire is burning.
Soot not only affects wood fireplaces but also gas fireplaces.
In some cases, soot production from a gas fireplace is simply the result of an old and inefficient gas fireplace.
As a gas fireplace ages, the gas fireplace can become less effective at combustion, leading to increased soot production.
If your gas fireplace is producing excessive soot, it is vital to take action to correct the problem.
Improper Airflow can cause excessive buildup of soot.
Cleaning the air vents and ensuring they are unobstructed can prevent this issue.
Eventually old age will begin to deteriorate the burner.
Soot is primarily formed when there is incomplete combustion of the fuel.
This occurs when the air-to-fuel ratio is imbalanced, leading to an insufficient oxygen supply during the burning process.
The result is the production of carbon particles, which deposit as soot on the gas logs.