ping a wine bottle sealed is probably the most important factor when it comes to maintaining a good wine.A cork is essential, as it keeps oxygen out of the wine bottle. If a bottle of wine is not airtight then it may become oxidized and undrinkableTraditionally, the only corks worth considering were those actually made of cork. Recently, however, many wine experts have recognized that cork may actually cause more problems than it solves.Cork, due to its malleable nature may have imperfections; these can result in the seal of the bottle not being as airtight as it could be and the wine being spoilt. In an attempt to avoid this problem, modern cork manufacturers may treat the cork with a chemical called TVA. Unfortunately, this chemical can cause the wine to taste and smell a little damp and musty.Having said this, cork is able to expand to fully fill the neck of the bottle, which therefore, still makes it the preferred option for special wines that need to be stored, over a long period of time.Plastic corks are becoming increasing popular, of late. One of the main problems associated with traditional corks is that the wine becomes corked. Plastic corks prevent this occurring. Great! I hear you say. However, there can be minor irritations with plastic corks. A plastic cork can sometimes be difficult to extract from the bottle and virtually impossible to fit back into a half drunk bottle.Another recent development is the widespread use of screw-top bottles. Until recently, this type of seal was used for only the cheapest of wines. Wine producers across the globe are now recognizing the benefits that screw tops provide. This type of seal ensures that wine is kept fresh; there is no chance of the wine becoming corked and the bottle can be easily resealed. In reality, the only reason that screw tops are not more popular is because of the ingrained snobbery associated with this method of sealing a bottle.No matter which type of cork you choose, it is important that you are able to recognize whether the wine has been properly sealed or not. A useful test is to see whether the top of the cork is level with the top of the bottle; if it isnt, then that particular bottle of wine is probably best avoided.If a traditional cork breaks when you are removing it - dont panic! Use a corkscrew to attempt to dig out the remaining cork. If this fails, simply push the remains of the cork down into the bottle. Contrary to popular belief, this will not destroy the wines flavor. You may have to fish out a few bits of cork, but the taste of the wine should remain unaffected. However, youd be wise to finish the whole bottle, under these circumstances!When choosing your wine, base your decision on the wine itself and not the type of cork. Resist the temptation to be a cork snob; a screw top bottle may just give you a pleasant surpriseSince Neil Best first pondered the question, Who made the first wine anyway? hes been recording his findings at Good Glug. This article forms part of the new and free Good Glug wine appreciation mini course. Visit now to get your copy.