Q: Is something wrong?
A: Probably not. Have a beer.
It's a pretty common thing, and quite understandable, for newbie homebrewers to be worried about whether everything is going right or not. After all, there are a lot of variables in the brewing process, and if you screw up one little thing, your whole batch of beer could be ruined, right? Well, no, not really. Keep in mind, people were brewing beer five and six thousand years ago, long before fermentation locks, modern sanitary practices, and even cultured yeast. There are things that can go wrong, but few of them will be severe enough to cause you to pour your beer down the drain. Here, we'll cover how to recognize when there is and is not a problem, and what you can do about it.
Okay, I wasn't paying attention, and my wort boiled over. What do I do?
This happens to every homebrewer at least once. Don't worry. This most commonly happens when you're initially trying to bring your wort to a boil. You've got the water boiling, you add your extracts and it takes longer than you expected to start boiling again. So, you go watch some TV or whatever, and before you know it, you've got one hell of a mess. When this happens, turn the heat down to low immediately, let the foam subside, then slowly bring the heat back up until the wort is boiling gently but steadily. It will not boil over again. Now quickly clean up with a wet rag or sponge. Your wort is a syrupy solution, and will get very sticky and difficult to clean if you don't take care of it right away.
This will normally not have any significant impact on your beer, unless it boils over for a very long time before you catch it. If this is the case, and a sizeable portion of your wort has boiled off, you can try to salvage it by adding more water and extracts, but you may prefer to just dump it instead. It also wouldn't hurt to have the number of a good maid service handy.
If the boil-over takes place while you're steeping grains before boiling your wort (see Homebrewing 201: Specialty Grains), this may or may not be a problem. There will invariably be some scorching of the grains, which will contribute a burnt flavor and a darker color to your finished beer. If you're brewing a stout, porter, alt or something similar, this isn't a big deal. You're shooting for a dark color anyway, and the burnt flavor will be subtle and can actually be a pleasant addition to the finished product. In other styles of beer, the flavor and color will detract from your enjoyment of the brew, and you should dump the grains and start over.
I dropped something into my wort during the boil! Is this a problem?
If you slipped and dumped in, say, an empty malt-extract can, this is not a problem - just use your wooden spoon to fish it out. The few seconds it was in there won't be enough time for it to contribute any metallic off-flavors. In fact, I usually submerge my extract containers in my wort for a few seconds in order to help get the last bits of syrup out of them. Pretty much any object that falls into your wort can be pulled out with no ill effects. The only real trouble you can get into here is if you drop in something soluble, like a can of ajax or a handful of beef bouillon cubes. You'll just have to use your best judgement as to how to proceed here. If it works, go with it - you accidentally spilled a little Ovaltine in your stout? Tell people you were shooting for that light hint of chocolate. It might even be good. If you can get it out, do it - you knocked in an open bottle of oregano? Grab your strainer and filter out as much as you can. If it's a normal beer ingredient, don't sweat it - it may alter the character of your beer, but it won't ruin it. Any kind of chemical is a killer, though - if any cleaning products fall in, you may as well dump it. Even if they're not inherently harmful, they're sure as hell not going to taste good in your pilsener.
I just realized I forgot to sanitize my funnel/blowoff hose/stopper/carboy. Is my beer going to get contaminated?
Probably not. Sterilization, while important, is often overemphasized. Some instructions warn you to sterilize the exterior of your yeast container before pitching, so the yeast won't pick up any bacteria on its way out of the package. This can't hurt, certainly, but it's going a little overboard. This prevailing emphasis on sterilization makes inexperienced homebrewers unduly worried when they forget something. The most important things to remember to sterilize are your carboy, your bottles and your bottling bucket. Everything else that comes into contact with your beer (hoses, funnels, stoppers, strainers, etc) only does so for a relatively brief period of time, and are thus fairly unlikely to introduce a bacterial infection into your beer.
That being said, it is still a good idea to sanitize all your hardware, as it will minimize the risk of contamination. This is especially true if you live in a household with pets, or if you have problems with bugs, rodents, children or other pests. However, if you do forget, don't beat yourself up over it. It's probably not a big deal.
How do I know if my beer is contaminated?
There are a few major giveaways. The most obvious is mold in your beer. Patches of mold floating on the top or clinging to the sides of your carboy are a pretty good indicator that you've got a bacterial infection. Be aware, however, that some varieties of yeast (especially ale yeasts, which are top-fermenting) may float in clumps atop your wort, so don't jump to any conclusions. Yeast can run from white to beige/tan to a light brown. Anything that's yellow, orange, green or other foreign colors can be assumed to be mold.
Bacteria can also cause an upsurge in fermentation-like activity, as some bacteria will consume certain chemicals or elements the way yeast consumes sugars. It can be hard to tell this from real fermentation, especially for an inexperienced homebrewer. Normal fermentation produces some strong odors that can be downright nasty, but bacterial infection will usually produce a distinctly different smell that someone with more experience can spot.
Okay, so my beer is contaminated. Is there anything I can do about it?
Well, you can try. The best thing to do is to rack your beer to another fermenter. See Homebrewing 203: Secondary Fermentation for information on how to do this. You will need another carboy. If the mold is floating on the top of your beer, take care to keep the siphon hose towards the bottom, and stop siphoning before any of the mold can get sucked into the new carboy. You'll lose a little extra beer this way, but it's better than losing the whole batch.
Once the beer is in the new fermenter, watch it carefully for signs of infection. As long as everything is fine, you can safely bottle once fermentation is complete. Depending on how long the mold was allowed contact with the beer, there may be some minor off-flavors, but if you caught the infection early, it won't even be noticeable. Keep in mind that beer is a pretty hostile environment to bacteria, and no known harmful pathogens can survive in it. This means that the only part of your body that will suffer any harm from drinking an infected beer will be your taste buds.
Fermentation just stopped all of a sudden, and I think it's too early. Is something wrong?
Probably not. The initial, vigorous phase of primary fermentation usually lasts 3-5 days. However, different varieties of yeast work on different schedules, and may ferment faster or slower than this. If you're brewing a lighter beer (lighter in terms of alcohol, not color), fermentation will be over sooner because there are less sugars to consume. If your fermentation lock is still bubbling more than once every minute or two, fermentation is still actively occurring. Just because it's not roiling and spewing forth gas and resins doesn't mean it's not fermenting. Let it be. Check Homebrewing 103: Primary Fermentation for advice on when fermentation is complete.
The other possibility here is that you've compromised fermentation by letting in too much light, which can kill your yeast. The occasional lifting of a carboy cover to check the thermometer or peek at the beer won't be enough to cause this, even in a well-lit room, but prolonged exposure to light will put an end to your yeast. If you think this may be the case, adding some yeast energizer or a new batch of active yeast can get things moving again.
It's been a long time, and fermentation is still going strong. Is this a problem?
Again, probably not. You may simply have a slow-acting yeast, or you may be fermenting at a temperature that is lower than ideal for your yeast. Most ale yeasts prefer temperatures in the range of 60-72 degrees Fahrenheit, and lagers tend to like the 46-56 degree range. Fermenting at slightly lower temperatures will make the yeast a bit sluggish, increasing fermentation time, but this will not have an adverse effect on your beer. You may also be brewing a higher-alcohol beer, which will take longer because there are more sugars for the yeast to consume. Finally, some sugars are more complex and will take longer for the yeast to break down. See Homebrewing 204: Alternative Sugars for more on this topic.
If your beer has been in its primary fermenter for two weeks or more, and most of the yeast has settled to the bottom of the carboy, you may wish to rack to a secondary fermenter if it's still bubbling away. This will allow your beer to continue fermenting without adopting any of the undesirable off-flavors which that layer of dead yeast can give off. See Homebrewing 203: Secondary Fermentation for more information on this.
My beer is flat! What gives?
There are a number of possibilities here. It could just be a problem with that particular bottle of beer. The cap may not have been on tight enough (you didn't use screw-top bottles, did you?) and the fermentation gases escaped instead of building the pressure necessary inside the bottle to carbonate the beer. Maybe you just got unlucky, and none of the priming sugar you dissolved made it into that bottle (although this is highly unlikely). Your bottled beer needs to ferment for about two to three weeks at normal fermentation temperatures. Maybe it's too cold where you're keeping your bottles, or maybe you need to give them more time. If this isn't the case, there might be no live yeast in the bottle. This is also rare - live yeast remains in suspension in your beer for a very long time. I've bottled beers after six months in a secondary fermenter and had them carbonate perfectly well. However, you may not have rinsed your bottles thoroughly enough after sanitizing them, and traces of bleach or other cleaners in your bottles may have killed the yeast. If you think no yeast or dead yeast is your problem, you could open each bottle and add a few grains of dry beer yeast, then cap them again.
My beer has a really weak head. What happened?
Your beer may simply not be fully carbonated (see above). Failing that, however, the most common causes of a head that never forms or fades very quickly are the drinker's fault, and not the beer's. Grease and salt will kill the head on your beer, as will soap residue. Your beer glass may be dirty, or may not have been rinsed thoroughly after washing. If you're having your beer with potato chips, pretzels, or any other greasy or salty food, the grease or salt will make its way from the food to your lips to your beer, and the head will suffer its effects. The addition of a quarter- to half-pound of malto-dextrin to your wort will also help head retention, as will bottling with DME instead of corn sugar.
My beer is nothing but head! How can I deal with this?
This most commonly happens in beers which have aged a long time before being bottled. The yeast goes into a hibernation-like state because of a lack of food (sugars), and when you add your priming sugar during the bottling process, the yeast wakes up with a vengeance. It undergoes a kind of yeast bloom similar to that which occurs during the initial phase of primary fermentation. The best way to deal with this is to age the beer for a while (two to four more weeks) in the bottles. The yeast will eat all the remaining sugars and go back into dormancy.
My beer looks cloudy, foggy or hazy. Why?
Welcome to the world of homebrew. Commercial beers typically go through several stages of filtration and often employ centrifuges to remove all possible sediment from their product. Most homebrewers have neither the equipment nor the dedication to go to such lengths to make their beers crystal clear. There are some things you can do, however. Using specialty grains in your beer will increase the amount of non-fermentable starches in your beer, which can make it cloudy or hazy. The addition of a teaspoon of Irish moss (available at your homebrew shop) during the last 10-15 minutes of your wort's boil will help clarify the brew. The Irish moss attracts the starches and bonds with them, and the moss itself is removed when you strain your wort on its way into the carboy. Secondary fermentation also helps by allowing more time for particles to settle out of your beer. Some cloudiness is pretty much inevitable, though, so don't lose any sleep over it.
My beer tastes weird. What's up with that?
This could be any number of things. If your beer tastes "skunky", this is most likely the result of exposure to light. In addition to its power to kill yeast, light also has a very adverse effect on certain hop oils and resins, which can produce the characteristic "skunky" off-flavor. This is why it is important to put your beer in brown bottles, never those which are clear or green. Because this is a reaction between light and hops, it is most common among light-colored beers (because light penetrates the beer more easily) which are very heavily hopped. Sunlight is the worst for this, and can literally skunk a beer in minutes. To see this in action, pour a nice light hoppy beer, such as an IPA, into a glass and immediately take a sip. Then go out on your porch and set the beer in direct sunlight for ten or fifteen minutes, and take another sip. I guarantee you will taste the difference.
If your beer has a tart or tangy flavor to it, this is usually a yeast issue. Remember when pouring a homebrew into a glass that you should do so slowly, leaving the last quarter-inch or so in the bottle, as this is where the yeast sediment resides. You may have poured the yeast into the glass, or the bottle may have been shaken up before you poured it, which would have stirred the yeast back into suspension. This is also a common result of leaving your beer in the primary fermenter for too long, sitting on that layer of dead yeast.
A cidery flavor or aroma is usually an indication that you used an inordinate amount of non-malt sugar in your beer. Corn sugar and cane sugar are the two major causes of this particular flavor. To avoid it, use only malt sugars in your beer. If you must use corn or cane sugar, it should make up less than 20% of the total sugars in your wort. This problem is more common among commercial brewing kits, which use a disproportionate amount of corn or cane sugar because it is cheaper than malt extract. Using corn sugar for your priming sugar when bottling will not contribute any noticeable cidery flavor, as you are using a relatively small amount.
Flavors that might be described as buttery or caramel-like are often caused by fermentation at temperatures slightly higher than recommended for your yeast. This is especially true of lagers, which are more sensitive to heat. Really outlandish flavors are generally the result of a bacterial infection of some kind. The easiest way to spot a bacterial infection in the bottle is to look high up on the neck, near the "beer line" on a full bottle. If your beer is infected, there will usually be a ring of scum or sediment on the inside of the neck.
Finally, don't forget to look to your recipe for possibilities. Some beers are characterized by a unique flavor or set of flavors. Weiss beers, for example, are supposed to have a sweet aroma and flavor reminiscent of bananas and cloves. Bocks often sport a residual sweetness and an almost maple-like flavor. You may have added an adjunct to your beer, such as pepper or licorice, that was a little stronger than you had expected. For flavors that are sharp or overpowering, letting your beer age in the bottle for a few weeks or months will mellow these flavors and make them more palatable.
That about covers most of the things that can and can't go wrong during the basic brewing process. If I missed something, or you've had a problem not discussed in this write-up, please feel free to /msg me and I'll be glad to add it. The most important thing to remember is that beer is really difficult to screw up. I've had batches where it was almost like Murphy himself reached out from beyond the grave and caused every possible thing to go wrong. They turned out fine, and yours will too. As the saying goes, relax, don't worry, have a homebrew.