VFI®-4171 70 D Casting Plastic

VFI-4171 70 D Casting Plastic is a slow-setting, two-component, polyurethane plastic with high physical properties. This material is capable of being machined with CNC or wood working equipment to create exact machined parts. Its slow demold time allows for more intricate molds and vacuum degassing before pouring. This material is made to be poured at 1/2” or thicker due to its slower setting speed and lower exotherm. VFI-4171 will cure in a silicone mold with the use of a pressure pot for a repeatable, uniform part.  

VFI-4171 70 D Casting Plastic is a slow-setting, two-component, polyurethane plastic with high physical properties.

Features & Benefits

  • Extended pot life for vacuum degassing and pressure potting
  • Able to pour castings over 2 inches in thickness
  • Produces durable and repeatable castings
  • Neutral color that can easily be painted and primed after full cure
  • Capable of being sanded and machined to a smooth and exact finish

Instructions for Use:  

Mold Preparation  

Release agents are required for all prototyping urethane molds. We also recommend using a release agent for any molding application to extend the life of the mold. Heated molds are not recommended for this product or any mold over 120°F. Do not use a two-part closed mold.  

Casting Process 

The B side (Poly) must be premixed once daily before each use, being careful not to introduce extra moisture or air. The A side (Iso) does not need to be mixed. 

Prepare a container that is an appropriate size for degassing, we recommended one that contains at least 2/3 of headspace in order to vacuum degas. Pour measured A side into the container and promptly follow by pouring measured B side into the same container. Mix until uniform by hand or power mixer. Mixing, vacuum degassing, and pouring must all be completed before the end of the pot life. 

We recommend pouring VFI-4171 at a minimum thickness of 1/2” or greater. When pouring thinner than 1/2”, use VFI-4170 70 D Fast Casting Plastic. To get full properties within 24 hours, post-cure at 150°F for 16 hours. It will reach full properties within 3 days without post-curing.  


*Always read the safety data sheet before working with chemicals   

Use chemicals only as directed and for their intended purpose. Do not dispose of chemicals down the drain. Most chemicals must be disposed of as hazardous waste.   

PPE to avoid all unnecessary exposures:  

  • Eye protection – wear approved safety glasses and any additional eye protection as necessary 
  • Hand protection – wear chemically resistant protective gloves (nitrile, butyl, or neoprene) 
  • Skin and body protection – wear suitable protective clothing 
  • Respiratory protection – in case of insufficient ventilation, wear suitable respiratory equipment. Respirator selection must be based on known or anticipated exposure levels, the hazards of the product, and the safe working limits of the selected respirator 

Product Limitations  

VFI-4171 contains isocyanate and can be irritating to the skin or toxic if inhaled.  

  • Incompatible materials – A side: water, alcohols, amines, bases, and acids. B side: oxidizers 
  • Conditions to avoid – heat and incompatible materials  
  • Chemical stability – stable under normal storage conditions  
  • Reactivity & hazardous reactions – no dangerous reaction known under normal use 
  • Hazardous decomposition products – A side: carbon monoxide, carbon dioxide, nitrogen oxides, hydrocarbons, and HCN. B side: may include, and are not limited to, oxides of carbon 

Potential Health Hazards  

  • May cause stomach distress, nausea, or vomiting if swallowed.  
  • May cause respiratory tract irritation. A side may cause allergy and asthma symptoms or breathing difficulties.  
  • May cause skin irritation or sensitization: redness, edema, drying, defatting, and cracking. 
  • Causes serious eye irritation: discomfort, pain, excess blinking and tear production, marked redness, and swelling of the conjunctiva.  

*If you are experiencing any of these symptoms, seek medical advice or attention. Call a poison control center or doctor if swallowed. 

Application Methods:

  • Pour

Available Packaging:

  • Tote
  • Drum
  • 5 Gallon
  • 1 Gallon