Which came first, designing the mold or designing the rubber duck? In the case of The Good Duck the bigger question was which process – blow molding, rotational molding, or injection molding – will result in the best rubber duck ever?

As most parents know, the first thing babies do when they grasp an object is to put it in their mouth. The Good Duck is made of medical and food grade materials that are soft and safe for teething children. FDA approved, PVC, phthalate, lead and BPA free, the duck is 100% made in the USA, and it floats.

Knowing he wanted a safe, soft, rubber duck that floated, Craig Wolfe, founder of CelebriDuck, also knew BPA and PVC free was the only way to go so visited tour of blow molding, rotational molding, and injection molding plants in Michigan, Indiana and throughout the United States. As he went from factory to factory researching processes and material he noted SPI was already using a soft material that could possibly work.

Wolfe explained the determining factor for choosing SPI Industries and SPI Blow Molding was the expertise of the people compared to other plastic manufacturing facilities in the Mid-West. SPI had the experience with reach and development to support the project. 

SPI came up with a formula that is reportedly safe for all ages.
SPI came up with a formula that is reportedly safe for all ages.

Material softness

The softness of the material, the product safety, the desire for different color ducks took much trial and error. Putting the correct material that is very soft into molds is challenging. Many CAD designs, re-molding, sculpting and testing to refine and rework molds was very time consuming and expensive.

The Good Duck design was originally planned to be injection molded. Once Wolfe started working with SPI Industries they started going in a different direction. With injection molding the Good Duck would be in two pieces. The two pieces would need to be glued together. ‘The plastic needed for the injection molding method would be too hard and would require welding,’ said SPI Engineers. A true rubber duck needs to be hollow to float. Blow molding it as one piece and sealing in the bottom was the solution.

The next challenge was determining wall thickness. The soft material they wanted to use with the characteristics that make the Good Duck safe and chewable doesn’t flow like normal resins. Getting the wall thickness exact took some time.

For the ducks to be completely safe, color needed to be molded right in the product. Adding color was a whole other issue because colorant adds weight, affecting the floating capability. Balance needs to be consistent and it is very intricate. SPI came up with a formula that is top of its grade with an age grading of 0 and up and is reportedly safe for all ages.

This story is reprinted from material from SPI Blow Molding, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.