a lot of soot

[prendi]

my friend has a gas fire and there is a build up of soot inside the fire and all over the fake coals,anyone know what causes this,or how to remedy this?

[The Builder]

It might be worth getting the fire serviced. prendi................. just in case the fire isn't burning properly, and it's causing the build up of soot. It sounds more likely that the soot is only what was in the flue already.............. assuming it's an old coal fire.
A service consists of "tuning" the burner and blowing it clear of soot. :o)

[johnk]

Has your friend got a carbon monoxide alarm or warning, if not he/she needs one immediately.

[heathfield]

Yep. Soot from gas is a sign that not enough air is being mixed with the gas to provide a clean flame.