Buildling a fire in your fireplace can be very dangerous if it's not properly contained. Harmful build-up accumulates in the fireplace creating an unsafe environment that can lead to unpredictable behavior of the fire. Cleaning your fireplace glass can also be dangerous if the proper precautions are not used, so keep your home safe by using careful methods while cleaning your fireplace glass.
Shut off the gas if you have a gas fireplace. Since it's possible for the gas to be on without a fire being lit, this step is very important. Free the area around the gas switch of any surrounding clutter that could be knocked over hitting the switch. If you have a wood burning fireplace, skip this step.
Mix equal parts vinegar and water inside a spray bottle to create a gentle cleaner. It's important to read cleaning recommendations for your specific fireplace glass to know what type of cleaner to use, but chances are most of us don't have that information handy especially if you rent your house. Creating this gentle cleaner will ensure that you don't harm your glass with harsh chemicals found in commercial cleaners.
Open the fireplace glass as much as possible. Most of the mess will come from the inside of the glass, so make sure to give yourself as much room as you can to access behind the glass for a thorough cleaning.
Spray the cleaner on the glass and wipe with a non abrasive, non cotton rag or paper towel. Many fireplace glass enclosures have tiny glass patterns, so make sure to give detailed attention to any crevices within the glass. You can use cotton swabs for these areas.
Scrub any cloudy white residue on the glass with the homemade cleaner and hot water. The cloudy white residue is most common in gas fireplaces. This will require some serious scrubbing. If possible consult your manufacture's manual for cleaning instructions as a recommended cleaner will remove this cloudy residue much easier than hot water. Using a cleaner without consulting the manual is not recommended as any remaining chemicals left on the glass may be flammable and potentially dangerous. The vinegar and water cleanser is safe and nonflammable.
Dry the glass thoroughly with a shammy or paper towel. Don't use a cotton rag or towel as any cotton particles left behind will be flammable and dangerous.