When you and the members of your household sit down around a fire, you want to enjoy both the warmth and the natural aesthetic in comfort. However, fireplaces accumulate dirt and soot with use, and this kind of buildup can make your fireplace look messy rather than cozy. In order to keep your fireplace in good condition, it's important to keep up with cleaning.
Preparation for Cleaning
While some fireplaces are made from brick or stone, many of them have mantels and hearths made of concrete, which requires a special cleaning approach. With a bit of effort, you can easily clean much of the wear and tear from your mantel and hearth, leaving them in great condition for future fires.
You'll want to prepare the area for cleaning for two reasons: first, so that the residual soot and dust in the fireplace itself doesn't ruin your attempt at cleaning, and second, to protect the surrounding flooring, walls or carpet. Some of the ingredients you'll need to clean the concrete can be damaging to other surfaces, so be careful and take your time. Make sure everything is covered with tarps, plastic sheets or newspaper.
Clean out the fireplace itself, removing soot and ash with a broom and dustpan. Cover any that you can't remove with coffee grounds, which will weigh it down to prevent dust from spreading in the air. Once finished, use a vacuum cleaner to remove loose dust, dirt and ash from the concrete surface.
Cleaning Concrete Fireplaces
If your concrete has been sealed, you're going to want to use a different approach than you would for unsealed concrete. With sealed concrete, you'll want to use 1 gallon of hot water with 1/4 cup of dish soap. Scrub the mantel or hearth with a scrub brush using this solution and then follow with a scrub using hot water to rinse out the soap. Allow the concrete to dry completely.
With unsealed concrete, you can start with dish soap or a general foaming all-purpose cleaner, using a scrub brush or metal bristle brush to work the foam into the surface. Make sure to wipe off any foam or bubbles and then follow with a rinse using fresh water. In all cases, allow the concrete to dry fully before using the fireplace.
Cleaning Difficult Stains
For tougher stains and buildup, you can use a solution of oxygen bleach in the water to attack the mantel or hearth. Oxygen bleach is a nonchlorinated bleach found in cleaning products like Oxi-Clean. It may be gentler than standard household bleach, but you'll still want to use goggles, gloves and as much ventilation as is available to you while working with it. It can also damage other surfaces, so be sure to keep it on the concrete and protect other areas.
In a gallon bucket, add between 1/4 and 1/2 cup of oxygenated bleach to the water and be sure to stir well until all of it dissolves. Use a stiff-bristled brush to scrub the solution into the concrete, moving slowly along the surface to remove the buildup. Allow the solution to sink in for 15 to 20 minutes and then rinse using a bucket of fresh water and a sponge to remove as much residual solution as you can. Stubborn stains may require a second pass or a paste of the oxygen bleach left to sit for a longer period of time.
If there are still visible stains after this, you're going to have to move on to harsher chemicals, like household (chlorine) bleach, trisodium phosphate or muriatic acid. If so, follow the instructions from the manufacturer carefully and remember that your safety comes first.