One of the most common problems in the glass industry is the Zirconium cord presence down the glass flow, commonly knowns as cat scratches.

This phenomenon uses to increase when refractories are close to the end of their campaign-life, and so when the structural integrity of furnace and channels is secure, using stirrer mechanism could help to increase glass quality.

But there are other good reasons to stir the glass, such as to enhance glass temperature homogeneity or when we colour glass in the forehearth; In this case it will be mandatory to install a few lines downstream the frit injection point.

Stirrer RST20

To address the above-mentioned issue Revimac developed its first solution many decades ago by providing to glass factory a mechanism that will stir the molten glass in the equalizing zone.

Recently we update our stirrer design with the new RST20. With this recent evolution, our system is now adopting gear-driven blade to increase longevity and reliability.

The most common set-up will be by using twin, counter-rotating, over-lapping paddle type stirrers, but many different combinations are available.

It’s possible to choose between solutions with 1, 2, 3, or 4 heads (stirrer) depending on the size of the forehearth channel and the needs of the customer.

This last version was chosen by container glass manufacturer Vetri Speciali, in its San Vito al Tagliamento plant, Italy where it installed Revimac RST20 stirrer mechanism on five lines.

Mechanical structure

  • Steel frame (portal) to be installed in the equalisation zone;
  • Manual hoist winch for lifting and lowering the stirrer heads;
  • Stirrer unit single or double (1+2, 2+1, 2+2)
  • Gear driven blade
  • Glass thermal homogeneity
  • Cord removal

Control system

  • Main Cabinet
  • Local Control Console


For a colouring forehearth there’s a specific version designed to stir the molten glass with the colourant (frit) to obtain a homogeneous colouration. Stirring station dedicated to glass colouring forehearth are customised in accordance with the pull, the temperature, the glass composition and the kind of colouring is needed to achieve.

Stirrer control unit could be integrated in the forehearth control cabinet.

Refractory stirrer

They can be of various forms and types, the Revimac RST system is compatible with all models in the market. They can be screw type, or paddle type.