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Northstar Polymers, LLC

3444 Dight Avenue So.

Minneapolis, MN 55406

Tel: 612.721.2911

Fax: 612.721.1009





Northstar Polymers, LLC is a member of Polyurethane Manufacturers Association.


Copy right reserved by Northstar Polymers, LLC 2000 - 2007.  Northstar Polymer prohibits duplication of the contents of this web site for the purposes of public display and/or using on another web site without a written authorization by Northstar Polymers, LLC.



Easy Mold Making Using Polyurethane Resins

Block Mold Using A Disposable Cup

With polyurethane mold-making materials, you can make a mold for a variety of products and parts. This shows an example of easy mold-making process for parts with patterns of the all dimensions. You can also upscale the mold by using wooden box or plastic containers. Please also refer to the mixing instructions for information on mold-making material, mixing, and handling.
1. Prepare an original. Coat with acrylic sealer if needed. If the original is made of wood, plaster, or other moist materials, completely dry it before the mold making operation. 2. If the original is made of a right material, attach a weight to stop it from floating. You can also attach it directly to the bottom of the cup.
3. After generously applying mold release (silicone release agent) on the model and the inside surface of the cup, place the bear in a cup large enough to hold the model. 4. Be sure to put it in the center of the cup at least 1/4" away from the inside wall of the cup.
5. Mix part-A and part-B. Follow the mixing instruction. 6. Pour slowly in to the cup. Be sure to release the air from the air traps on the model by titling and shaking the cup.
7. Make sure the liquid is covering the model completely. There should be at least 1/4" of liquid above the highest part of the model. Cure for over night. Refer to the instructions for the proper temperature. 8. After it is cured, use a spatula to separate the resin from the cup to demold. If you do not have to re-use the cup, you can break the cup to demold.
9. Take the resin mold out of the cup. 10. Use a utility knife to cut one side of the mold. Choose the most inconspicuous place. Be sure to wear gloves to avoid personal injuries.
11. Flex the mold and full the model out. If possible, one person can stretch the mold while another person is pulling the model. 12. To cast your composite (plaster this time), apply a proper mold release for the composite material (vegetable oil this time).
13. Use rubber band to enforce the mold. 14. Pour the composite material (plaster this time) to the top of the mold.
15. After the composite is cured, demold in the same way as demolding the original. 16. Finish by cutting the excess and machine the part line if needed.
Side-by-side Comparison Side-by-side Comparison
You can pour a variety of molding compounds such as plaster, concrete, filled resins, soap, wax, or casting resins such as solid polyurethane, polyurethane foam, epoxy, silicone rubber, latex and other materials.
If you are using polyurethane foam or any compound that expands when cast, you can make an instant compression mold to make compression molded parts. *

If you are molding foam or expanding compound, use two steel plates to sandwich the mold after you put the molding compound in the mold.


Clamp tight to make an instant compression mold.

* Polyurethane foam requires temperature control. You need to use special mold release for foam. Please refer to the foam molding instruction for the information.

Before operation, please be sure to read the instructions from Northstar Polymers regarding the mixing, curing, and handling of the material. Also, please refer to the Material Safety Data Sheet for each components for the safety information of the each material.

For any questions, please call Northstar Polymers.


Northstar Polymers, LLC

3444 Dight Avenue South

Minneapolis, MN 55406

Tel: 612.721.2911

Fax: 612.721.1009

E-Mail: info@northstarpolymers.com


Notice: All of the statements, recommendations, suggestions, and data concerning the subject material are based on our laboratory results, and although we believe the same to be reliable, we expressly do not represent, warrant, or guarantee the accuracy, completeness, or reliability of same, or the material or the results to be obtained from the use thereof, neither do we warrant that any such use, either alone or in combination with other materials, shall be free of the rightful claim of any third party by way of INFRINGEMENT or the like, and NORTHSTAR POLYMERS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, OF MERCHANTABILITY and FITNESS FOR A PARTICULAR PURPOSE.