Thoughts on Sediment in Wine | Nov 26, 2017 | By Christian Palmaz

Have you ever wondered why there is what looks like sediment or crystals on the bottom of your cork or on the inside of the bottle?  Or why some wines seem to have more than others?  You certainly aren’t alone.  We receive a handful of emails every year asking these exact questions.  Let’s deep dive into the interesting world of why wines form crystals.

First of all, the crystals, or precipitated tartrates (KHT Potassium Bitartrates) as they’re formally called, are completely normal.  In fact they are considered by many a sign of balanced winemaking.  Even though most high-end wines are filtered to less than a micron just prior to bottling, solids form when potassium and tartaric acid, both naturally occurring components in grapes, bind together to form a crystal.  The crystal tends to prefer growth on rough vs smooth surfaces hence it’s deposition on the cork’s bottom.  This sea-salt like substance is completely harmless and natural.  They do tend to form somewhat faster in wines cellared at colder temperatures (below 40F).

Palmaz Vineyard’s white wines undergo a practice called cold stabilization which forces out tartrates from the wine to minimize this effect.  We and many other high end producers do cold stabilization in our white wines for cosmetic purposes because they are see-through.  The tartrates can appear on the bottom of the bottle confusing people to think they are glass shards.  It is not often done on high end reds because, aside from the wine not being see-through, the presence of tartaric crystals is often considered a form of quality or balanced wine making.  Some winemakers also believe cold-stabilizing reds can cause the loss of certain desirable characteristics.  One could be slightly intrigued if not suspicious by a Cabernet or other full body red that had no tartaric formation on the cork.

Vineyard parcel selection can also play a factor in how much a wine might precipitate crystals.  Soils across the estate will have naturally varying levels of K+ (potassium) which end in the grapes.  As Palmaz’s winemaking team design the estate blend from scratch each year you can expect different vintages to have slightly different tendencies to precipitate tartaric crystals based on which parcels contributed to the blend.

Since time also plays a factor in the amount of precipitates found in a wine, older wines may have heavier deposits of tartrates that have fallen to the bottom of the bottle.  It is an acceptable practice to decant these wines through a wine strainer.  You can also simply pour the last glass very slowly while turning the bottle to help catch the sediment on the bottle’s neck.

The crystals found on the cork or the glass are just another interesting way a wine has to tell you it’s story.  Next time you open up a bottle, take a second to have a look.  Wine really is a living liquid!