By: Francisco Ibarra, Date: 02/12/2018

Liquid resin molding, or resin casting, is a manufacturing method where a liquid is used to fill a mould. The liquid hardens and the result is a plastic in the shape of the mould. The liquid used in liquid resin molding is known as a synthetic resin, which is a viscous liquid capable of hardening permanently. While there are various classes of synthetic resins, the most popular are thermosetting plastics.

In thermosetting plastics, the process by which the plastic or liquid resin is cured, or hardened, occurs through the cross-linking of polymer chains, which is brought about by the addition of heat, chemical additives, or suitable radiation. In other words, the synthetic resin is a monomer that polymerizes into the polymer when heat is added and allows the plastic to harden.

Video on the process: https://www.youtube.com/watch?v=I7n-uMmJevM

• Leo Hendrick Baekeland introduced Bakelite, the world’s first synthetic plastic, in 1907. This marked the start of the Polymer Age. Bakelite, was a thermosetting resin that once molded could retain its shape even if heated or subjected to various solvents. Baekeland started semi-commercial production in his laboratory and in 1910 he formed a U.S. company to manufacture and market his new industrial material. By 1930, the Bakelite Corporation occupied a large plant in Bound Brook, New Jersey.

• Primarily used for small-scale production/small products like industrial prototypes and the dentistry industry. However, it can be used to produce any small product including toys, unique models, figures, and even jewelry.
• This manufacturing process allows for the creation of a product that is detailed and would be costly to make in other ways. With liquid resin molding, one can add any detail during the sculpting process where the clay sculpture is made. Once one has the part or sculpture desired, a mold is made and a synthetic resin is added. The part can be easily replicated as many times as desired.  
• As previously mentioned the products created through liquid resin molding can be of any shapes and minuscule details. In theory, anything that can be created through the sculpting process can be turned into its plastic form, or replica through this manufacturing process.
• Shortcomings to this manufacturing process are that some liquid synthetic resins may take up to 72 hours to completely dry. In addition, the mold in which the casting is creating degrades with use, meaning only a limited number of high-quality castings can be created. A lot of times, castings have to be smoothed out and cleared of impurities.

• What is the step by step processes?
  1. The first step in the Liquid Resin Molding manufacturing process is in preparing clay, usually in a pancake-like form.
  2. Place the clay on a board and place the item to be molded in the center of the clay.
  3. Make holes with a small tipped item around the object.
  4. To make a box for the mold:
     • Take measurements of the length and width of the part in the clay.
     • Add 1 inch to the measurement. This will give a 0.5-inch border all the way around.
     • Cut a strip of foam board to the desired thickness; this thickness should be at least two times the height of the part that is sticking out of the clay, but not too tall.
     • The foam board strip should be marked with the measurements of the border needed. Alternate the measurements, i.e., 3-in, then 4.5-in, then 3-in and again 4.5-in. At these marks, score one side of the foam board.
     • This score or cut should not go all the way through the board.
     • This will allow for the board to be folded at these marks.
     • Tape the ends together to form a four-sided box.
  5. Place the box around the part in the clay, applying enough pressure to make an indentation or mark in the clay. Remove the box and cut the clay at the marks that were left behind.
  6. Once the clay is cut to size, again place the box around the part and now around the cut clay. If done properly, the clay should fit in the box.
  7. With the box secure, smooth the clay to the inside of the box.
  8. Pour the mold to fill the box.
  9. Now that the silicone has dried, remove the clay that is securing the box to the chipboard. Flip the box over and carefully remove the clay that was once the bottom.
  10. Use a mold release to coat the exposed silicone.
  11. Split the two halves of the box.
  12. Place the two halves of the mold together matching up the keys that were made of the mold halves. The two halves should simply be held together; do not squeeze or deform the mold. The mold is ready for casting.
  13. Based on the part that was molded, estimate or measure the amount of plastic resin needed to be mixed and slowly pour the mix into the mold or hole that leads to the mold.
  14. Let resin harden for time determined by manufacturer.
  15. Clean the finished product.
• For a more detailed process visit 

  http://www.instructables.com/id/The-Complete-Guide-to-DIY-Molding-Resin-Casting/

• Liquid resin molding, or resin casting, makes use of a liquid known as a synthetic resin, which is a viscous liquid capable of hardening permanently. While there are various classes of synthetic resins, the most popular are thermosetting plastics. In thermosetting plastics, the process by which the plastic or liquid resin is cured, or hardened, occurs through the cross-linking of polymer chains, which is brought about by the addition of heat, chemical additives, or suitable radiation. In other words, the synthetic resin is a monomer that polymerizes into the polymer when heat is added, which in turn allows the plastic to harden.

  To improve one’s understanding of how this manufacturing process works, the thermosetting resin used polymerizes by mixing with a curing (hardening) agent that is the catalyst for the reaction. Such reaction occurs at room temperature and normal atmospheric pressure. The resins get their names from plant resins but are simply synthetic monomers as previously mentioned. As monomers, they allow the creation of polymers, which in this case are polymer plastics. Various kinds of synthetic resins include polystyrene resin, epoxy resin, acrylic resin, and silicone resin.

• This manufacturing process can be done by the general public. No skill sets, expertise, or education are necessary to manufacture through Liquid Resin Molding.

• Smooth-On Silicone Mold Making, Liquid Rubber - Trial Size 2.8 lb: ~ $24.00

• Mold Release and Conditioner, 4 Ounce: ~ $10.00

• Mold-shaping tools should cost no more than ~ $10.00

• Clear Casting Resin With Catalyst 32 Ounce: ~ $32.00

• Minimum Liquid Resin Molding Manufacturing Price: ~ $76.00

  Competitive Process: (3D Printing) Printers run in the thousands of dollars but public use of them only cost about $3.00 for the first hour of 3D printing and $1.00 for additional printing per hour.