Nominal Filters vs. Absolute Filters for Wines: What Are the Differences?

Wine needs to proceed through numerous processes to transform from grapes into a delectable beverage worth celebrating. Filtration is one of these processes, and it refines the look and quality of the wine by removing unwanted particles from the wine prior to bottling. Today, there are different types of filters to use to accomplish this with the main ones being nominal filters and absolute filters. We share the following details about both these filters in order for you to gain an understanding of their differences.

What Are Nominal Filters?

Nominal filters come with a variety of pore sizes with the most common being in the form a filter pads or other depth filters. The wine passes through these filters, and the unwanted sediment particles randomly float through the different channels in the filters until they settle on the channel walls where they are retained through adsorption or entrapment. While these filters can be effective, they do have the following disadvantages:

  • Microbial growth can occur in the filter, and this contaminates the wine.
  • The wine can encounter problems with flowing smoothly due to media migration as fragments of the filters break loose during filtration.
  • A small amount of wine may stay in the filter and have to be removed with a special process to be returned to the main tank.

What Are Absolute Filters?

Absolute filters contain a porous, geometrically consistent matrix. They work by retaining unwanted sediment particles on their surface with the help of sieving equipment. Pore sizes of the matrix are set during manufacturing. These filters receive their name from the fact that the filtration is absolute since any particle that is larger than their pore size will be retained on the surface of the filters. All of these filters are membrane-style ones, and they are for the final filtration right before the bottling process takes place. The advantages of these filters include:

  • No media migration occurs at any time during filtration.
  • As the larger particles layer on the filter, they might prevent particles that are smaller than the pore size from staying in the wine.
  • You can derive a specific efficiency with the pressure differential and flow rate of the wine.
  • Microbial growth is not possible since the membranes are extremely thin.
  • The disadvantages of the absolute filters are:
  • Certain small sediment particles may not pass through the membrane easily, and this might lead to a blockage in the flow pattern of the wine.
  • Since the membrane filters work with surface retention, they have a low capacity for handling dirt and debris. Due to this fact, only wine that has been pre-filtered through other means should flow through the absolute filters for optimal results.

For further details about nominal filters versus absolute filters and their differences, consult with Grapeworks Consumables. We offer a variety of each type of filter for your consideration.