Handy Hints

Polyurethane Resin

Polyurethane resins are incredible materials for reproduction. They offer great strength, can be used thinly and can be filled very successfully, which allows them to replicate many different effects.

Polyurethane resin is a very sensitive material to moisture and cold and my tips for problem free usage are:

• Ensure that part A & B is thoroughly shaken/stirred before decanting as this will guarantee that all the chemicals in the polyurethane are evenly dispersed throughout the resin.
• Ensure that the polyurethane is warmed to 20-25 degrees C
• Always mix polyurethane part A & B thoroughly together, then decant into a clean plastic container and mix again before use.
• Ensure that any fillers or pigments that are to be added are free from moisture. Heat the filler powder to dry it if unsure.
• Polyurethanes are so chemically balanced it is essential that when mixing a filler you follow these guidelines:
  • For a slow cure polyurethane – parts A & B are well mixed mechanically prior to filler being added and well blended again afterwards. They should then be decanted into a clean container and mixed again before use
  • For a fast cure polyurethane – mix filler into part B and blend. Add part A into the mix and ensure thorough mixing. It is important to decant the entire mix into a clean container then mix again before use. A Squirrel mixer is recommended as speed is essential.
• Always protect any remaining raw material from moisture by using an Xtend-it gas blanket each and every time the container is opened and always before storage of any remaining material.

Good house keeping and method will always ensure quality castings.

This hint appeared in our January 2005 Broadcast Newsletter.