Nomacorcs are the synthetic corks that Winexpert uses and recommends most frequently. We prefer them even to natural cork, or to agglomerates of natural cork with silicone surface treatments.
Nomacorcs display several advantages over other sorts of cork. One of those is the neoprene coating on the outside of the cork blank. It is slightly tacky, which allows the cork to fill in gaps around any irregularities on the inside of the bottle neck when it’s inserted. Yet under shear, the neoprene is quite slippery, as the molecules align along the friction of the shear. In plain terms, this means they go into the bottle as though greased.
Yet after the cork has been inserted, those same molecules randomize again and 'set' the cork in the neck of the bottle. And when it’s time to pull the cork out, the molecules respond to the pull and line up again, and once again the cork moves very easily as it is removed. So both insertion and removal are easy, yet the cork 'sets' very firmly in place when it’s inside the bottle. The one drawback is that you can’t put these corks in with hand corkers.
But there are even more important advantages to Nomacorcs. Aside from the fact that they don’t chip, don’t leak, don’t rot, and don’t dry out, they never contaminate the wine with trichloranisole. This chemical is the source of 'corky' aromas in wine, and it generally contaminates about 2% of all natural cork supplied to the home market in North America. In practical terms, that would mean that out of every 100 bottles you cork, two of them would spoil, not in spite of the cork but because of it. This simply never happens with Nomacorcs.
So what exactly is the composition of these Nomacorcs, that produces the qualities that make them so preferable? They are made from a Super High Density Polyethylene (SHDPE), which is a version of the material that plastic fermenting pails are made from. The raw materials used are chemically and physically inert, guaranteed to meet FDA and international food industry standards, and on top of that, they are recyclable. The material is an engineered plastic, a highly elastic, chemically inert polymer formulation. The actual formula, of course, is proprietary information.
Nomacorc foams the material with an inert gas, producing a closed-cell foam similar to Styrofoam, which contains no organic material and does not degrade over time. Using a patented technology called co-extrusion, the company creates a foam inner core with a flexible outer skin. A Nomacorc has excellent rebound characteristics, returning to 99% of its original size in less than five seconds after pressure has been put on it. It also maintains a very even cross-section of density throughout the cork.