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Open-top Mold
















































































































































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

Open-Top Mold

With polyurethane mold-making materials, you can make a mold for a variety of products and parts. This shows an easy method of mold making for parts with a flat back. You can also make all-side parts with these materials by making either a block mold or two-part mold. Please also refer to the mixing instructions for information on material, mixing, and handling.


1. Use polymer clay or any forming material to form the model. If there is any moisture, dry completely. 2. Bake the clay if necessary, and seal with acrylic (or any plastic) sealer and dry the sealer.
3. Use aluminum foil to make easy disposable container. 4. Apply mold release.
5. Apply mold release generously on the model. 6. Apply mold release on the backside as well.
7. Place the model in the center of foil and fold up the edges of the foil to make a casing. You can make exact size to optimize the size of mold for your model. 8. Make sure there is at least 1/4" space between the edges of the model to the walls of foil casing.
9. Place it into frame or anything that can support the weight of the liquid mold-making material. 10. If there is space between the foil casing and the frame, use cardboard paper or any solid material to fill the space.
11. Pour polyurethane mold-making material mixture. (Refer to the mixing instructions.) Pour it slowly to avoid entrapping air on the model surface. 12. Pour it to cover the entire model and have at least 1/8" to 1/4" layer of mold-making material surrounding the model. Let it cure (Refer to the mixing instructions.).
13. When it cures, peel off the aluminum foil. 14. It does not matter if you do not take all of the foil pieces off.
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. **

15. 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.


16. Clamp tight to make an instant compression mold.


*You do not have to use aluminum foil if you want to make wooden or plastic casing. If you are making a solid casing, seal the surface with slick coating and dry, make sure it can be disassembled for demolding.

** 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.

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.