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Palmer No-Bake Mold and
Core Vent Tubing

PalmerVent for Rammed Cores & Molds

Providing an easy way for trapped gases to escape from either a core or mold is critically important in preventing defects. PalmerVent is made of synthetic venting material, specifically to provide a path for evolved gases to escape from a core or mold. The resulting reduction in gas pressure within the core prevents porosity and blow defects in the casting. Synthetic venting is generally used in hand rammed cores although it can also be used in molds.

PalmerVent is placed in the sand away from the surface and terminates at a core print. It is most beneficial when placed in sand projections on a core that are going to be surrounded with metal. It is essential that the venting not contact the surface of the core because that will allow molten metal to run into the vent blocking the escape of gases and actually increasing the chances of gas defects. It is also important to make certain that metal does not run into the vent from the core print area. If the core print is not tight, core muds or rope gaskets must be used to eliminate metal from running into the vent.

Documentation – for quality assurance

To ensure replications, we recommend that the vent location be documented in core pictures or drawings so that all coremakers place the same size vent in nearly the same area in every core. The picture or drawing should indicate the diameter of the venting material, the distance from the core surface that it is to be placed, and the core print that it is to be terminated. Coresetting documentation should indicate the importance of preventing molten metal running into the print area. Sometimes it is necessary to provide a vertical escape route in the mold portion of the mold from the print through the cope mold or out through the parting line.

Cold Box Cores

Generally it is more challenging to incorporate synthetic venting in Cold Box cores because the venting will move as the sand is blown into the core box and it will be against the surface of the core. Occasionally, if the core has the potential to place a reinforcing rod from a print, it is possible to wrap the venting around the rod is a spiral fashion and it will allow gas to escape along the rod. The venting can be incorporated in hand rammed molds horizontally from a core print to the external side of the mold (and can be used to vent mold projections from the top or bottom). Occasionally some of the larger diameter venting is used to allow room for sand expansion preventing hot tears.


  • PalmerVent is a permeable, woven tube that can substantially improve your core and mold venting procedures. Its porous design can eliminate the never ending problems that come from insufficient core venting. PalmerVent can also be used in many core applications to impart a hollow section of core for improved collapsibility. 
  • PalmerVent is available in sizes ranging from 1/8" to 2" diameter. PalmerVent is extremely flexible allowing it to be configured as needed within the core. When placed in the core box during ramming it provides a positive, open channel through which gases generated during pouring can escape to atmosphere. 
  • As an integral part of the core, PalmerVent creates a permeable ductwork to route combustion gases out of all areas of the core. PalmerVent provides a cost effective, consistent way to eliminate the cleaning room problems and scrap castings caused by improper or insufficient core and mold venting. 
  • Unique construction offers excellent rigidity when used in rammed and compacted mold situations.

Available in:

  • 1/16" - 300' Roll - PN307A
  • 3/16" - 300' Roll - PN308A
  • 1/8" - 300' Roll - PN300A
  • 1/4" - 300' Roll - PN301A
  • 3/8" - 300' Roll - PN302A
  • 1/2" - 300' Roll - PN303A
  • 3/4" - 200' Roll - PN304A
  • 1" - 100' Roll - PN305A
  • 2" - 50' Roll - PN306A


General Usage Procedure

  1. Cut PalmerVent to the desired length for the core or mold area to be made. Generally, the less permeable the sand, the more venting should be used. Vent material should extend at a minimum to the core print area for later venting through the mold. If used in a mold application, run the end of the vent system to the side of the molding box or parting line if using a flask. A vent open to atmosphere upon completion will be far more effective than a sealed vent. 
  2. Check fit in the core or mold area. As necessary, PalmerVent can be tied in loose knots to surround a particular feature or simply laid flat. If two vents cross, tie them together loosely to combine their venting effectiveness. 
  3. Once venting is fitted, begin filling of the core or mold box. The venting should be placed as close to the mold to metal interface as is practical without the venting going into the metal cavity. Generally, the closer the venting is to the surface, the better the gas removal will be.

Prevention of Defects with Venting

Click here to View Article (English).
Click here to Download English PDF.

Click here to View Article (Spanish).
Click here to Download Spanish PDF.

Click here to request vent tubing samples.

Palmer Engineered Products, Inc.