"Last year's grease on the grill, last year's ashes on the bottom. That's what makes a Bundy Burger special."Al Bundy, Married With Children, 1989
Grease and oils get rancid, particularly in hot weather, and rancid grease on your grill grates can make your food taste bad. Rancid grease on the bottom of the grates can vaporize and flavor the food, too. Then there's the black crust. It is mostly carbon and it tastes like burnt toast.
It is vital that your food go on clean grates. Before you cook, get the grates ripping hot, close the hood, wait about 15 minutes or until the smoke subsides. That's grease smoke and it does not enhance flavor like wood smoke. It coats the meat with acrid soot. The heat will burn off the grease and turn any food or sauce bits to carbon. When the grates are hot, flip them over and get the underside.
A better practice is to clean after a cook to discourage insects from hanging around between cooks. Letting charcoal burn itself out and carbonize food residue is a good practice, but leaving a gasser or pellet burner on can get you in trouble. If you are forgetful, as I am, especially after a meal and wine, it is easy to accidentally leave the grill run all night and burn through a bottle of propane or a bag of pellets, so either set an alarm or just shut down when you bring in the food.
I start with a scraper like CharGon (below) and then I dip a wire brush (below) in water and scrub with the wet brush, creating steam in the process. Then I follow up with a damp cloth to pick up any dust, chunks, or wire bristles left behind.
You may want to try a handheld steam cleaner once or twice a year for both your grates and the interior of your grill. A mild enzymatic cleaner like Dawn is probably safer than a chemical cleaner whose residue could be noxious.
If your grates are reversible, flip them over between cooks. That will keep glop from building up on the underside.
When you are done cooking, if you have a gasser or pellet burner, it is a good idea to leave them on to burn off gunk, then scrape them. If you are forgetful, as I am, you can accidentally leave them run all night and burn through a bottle of propane or a bag of pellets, so set an alarm.
Do not run grates through the dishwasher! The grease is pernicious and can coat everything inside the diswasher, and you'll be sleeping on the couch for a while. Periodically take the grates off the grill and lay them on a cloth on the ground. Fill a bucket with hot water and dish detergent. With a brush, scrub both sides and rinse thoroughly. Be warned, if you do this on cast iron it will likely lose some of its non-stick properties, but sometimes, especially if there is rust, you have no choice. Just make sure you thoroughly dry and oil cast iron after washing. You can use a scrubby sponge, and even steel wool on stainless and plated if it has not been chipped.
The AmazingRibs.com science advisor, Prof. Greg Blonder, says "My end-of-year clean is to place the grates in a large tub, pour on boiling hot water, mix in some Dawn, and come back the next day. Cleans off easily with a stainless steel scrubby." My end-of-season clean is with a pressure washer and then dish soap.
Beware of bristle brushes
Be careful with bristle brushes, especially cheap brass bristle brushes. Bristles fall out. Every year there are scores of sad news stories about people eating meals with bristles hiding on them. The bristle gets stuck in their throats or digestive systems, and repairs can get pretty ugly. Every so often someone dies. Here's an article on the subject from the Center for Disease Control documenting six (!) cases in Providence, RI, in one hospital system in 15 months! The X-rays here are from that article. Think I'm making a big deal out of nothing? Google "grill brush wire stuck throat".
So be sure to look your cooking surface over after brushing or give it a quick wipe with a damp cloth. I've even had readers tell me they run a half an onion or lemon over the grates after brushing. Make sure you have a good bright light pointed at your cooking surface. I have included some wire bristle brushes below that I have used that do not shed. But as soon as one bristle comes loose, others will surely follow, so if you see a brush losing bristles, please discard it immediately.
There are a number of commercial grill grate cleaning options available. You can easily rig one up on the cheap:
A block of oak. You can build your own by simply taking a block of hardwood like oak and a heat-proof glove and rubbing the wood on the grates. If you do it right, eventually you will wear grooves in the wood that fit the grates perfectly.
Aluminum foil. If you have a lot of stubborn grease, lay a sheet of heavy duty aluminum foil on top of the grates, put some weights on it so it doesn't float up with the hot air, and let the fire rip for five minutes. Then use tongs to remove the foil, crumple it, grasp the wad of foil in the tongs, and scrub the grates. Take a big ole wad of foil, put on a heat-proof glove, and scrub. You need heat proof gloves, and more than one wad, which has to be thrown out.
CharGon. CharGon is a solidly build grill grate cleaner with a U-shaped tip that makes it easy to scrape the tops, sides, and bottoms of round grill grates with no risk of rogue bristles and the health hazard they present. It takes a bit longer than brushes, but it does a better job.
About Our Medals, Awards, Product Reviews, And Ratings Steamfast SF-320 Portable Steam Cleaner. This is the heavy artillery. It takes a long time so this is not something to use after every cook. I use mine once a year to deep clean and more often on the deflector plates on my pellet smokers. These steel plates lie directly below the cooking grates and gan get mighty greasy. Steam does the trick. Also come in handy in the kitchen and bathroom!
Grillfloss. Similar to the Billy Bar, the angled head makes getting the sides and undersides of grates easier. There are two semicircular scraping surface that fit all thicknesses. Like the Billy Bar, this takes time. The biggest problem is that the tip is not very thick and it can bend and eventually break. You can buy replacement tips, but I would prefer to start out with a sturdy one.
Weber 18-Inch Bamboo Grill Brush. Still the easiest, and most effective way to remove grease. Heat the grates and then brush. Simple. There are a variety of brushes like this with rustproof brass bristles but the Weber is my favorite because it is well built. Some have flat scrapers on the end as well as the brush. I like this model because the C shaped scraper on the end.
The Last Brush. This long handled tool is perfect if you have a deep barbecue pit or catering rig. With two inch bristles that appear to be well anchored into the wood head, there is also a steel scraper, a 36" long wooden handle, and a leather strap for hanging.
BBQ ICU. This is a stainless steel rack that you can use to mount your grates to and use to really do a thorough cleaning on both sides. The manufacturer will even sell you a kit that includes a tub in which you place the rack as well as scrubbies, scraper, and degreaser.
GrillStone Grill Cleaner Starter Set, with Handle and Two Blocks . These pumice-like bricks are great for cleaning wire cooking grate. Do not use them on porcelain or cast iron grates. They are very fast, much faster than Grill Floss or Billy Bars, but they get only the tops. Each brick will scrub about 100 grates before it wears out. They are made from ground recycled glass and they leave a bit of dust behind, so you need a brush to finish the job. It's the microscopic glass dust that makes me nervous. There are other brands of Grill Bricks available.
Tool Wizard BBQ Brush. This device uses a woven stainless steel pad that does a great job of cleaning the grates. At first. It sounds great in theory, and it gets good reviews from others who haven't really used it, but performance is another thing. In theory the scrubber can be removed and run through the dishwasher, but if it is greasy, it can really slime the dishwasher and anything in there. When the scrubber gets disgusting and starts falling apart you can buy replacements, but they are not cheap, and they break down quickly. Before long it begins to slide side to side and unravel. You have to be careful, because when it starts to disintegrate, the woven steel can fall off onto the grill and could get into your food.
T-Brush. This is a large brass-wire brush that used to be one of my faves until it started shedding bristles. The bristles are not glued in, they are held in by twists in a metal bar connected to the handle. Once one or two fall out, the rest come loose more easily. It is very rare, but there have been choking incidents when bristles on the grate got onto food and were ingested.
Scrub & Spray Brushes. These look great on paper. There are replaceable stainless steel brushes and you can drip water while you scrub creating steam. Alas, in practice, I was unimpressed. You have to fill it with water, open a small spigot, scrub, and close the spigot. I didn't think the steam made that much of a difference. I get better results with a simple brush dipped in water. And in winter the water freezes unless you empty it after each use or store it in the house, and nobody wants a greasy grill brush in the house. Besides, I'm always wary of replaceable brush scrubbers. Last time I bought one, at a premium price, the company went out of business within six months.
Grillbot. This company has succeeded in doing something very well: Getting publicity. Scores of publications and TV shows have featured it as a cool device and gift idea. Unfortunately, I don't think any of them have tested it. Here's how the bot works: Turn it on, then close the lid of your grill, and it loudly and randomly trundles around, banging into the sides of the grill while spinning brushes attempt to clean the grill grate. Problem is, it doesn't do a very thorough job, and it only cleans the top of the grate. Of course the undersides of the grate are usually loaded with stinky grease that will burn and smoke and make your meal taste bad. The bot I bought shed one of its bristles after three uses. And if you forget to close the lid, the bot will drive right off the grill onto the deck and drive around there, assuming it doesn't break on impact. If it drives off the edge of your deck and you try to catch it, the bristles will shred your hand. You absolutely do not want to put this device on a hot grill because the plastic will melt. Nevermind the fact that hot grates clean easier than cool grates. If, despite all odds, you prefer this bot over other grill cleaning devices, you should know that after its bristles get all gunked up, you can buy replacements for $10.