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New application for infrared curing: Latex molds

October 3, 2001

We've shown that marrying latex with infrared will dramatically cut the production time in the manufacturer of molds. We were interested in experimenting with manufacturing the molds with a high solid content latex material instead of some other materials usually used, such as aluminum.

Latex offers many advantages for mold making. It is easy to use, low cost, and relatively durable. Multiple layers can be simply brushed on the model. The molds usually have to be supported with a plaster or fiberglass outer mold. Often cheesecloth or burlap can be added between the last few layers of latex for support. In addition, latex is a relatively non-toxic material.

The primary disadvantage of the latex mold making process is the time investment required. Often 12 to 15 coats of latex are necessary to make a mold that is ¼" thick. Under the best of circumstances, a maximum of three coats can be applied per day depending on temperature, but sometimes only two coats can be applied, as each latex coat must air dry. Therefore, it takes several days to make a mold. Given the variability of the air drying process, it can take a week to make a mold.

Having had previous experience using Infrared Heating (IR) for curing latex glues for a shoe manufacturer, AE decided to attempt to cure this latex material with IR.

After testing various IR wave lengths, success was achieved and we were able to demonstrate that it is possible to cure this latex and make molds in a matter of hours, not days. Or to restate this finding, a process that currently takes a week can now be done in a few hours.

To demonstrate that the latex mold that was built would actually work in practice, we took the testing one step further. The 16-layer mold was cut from the model to form two halves. This was not an easy process as the latex is extremely tough. However, in practice some standard separating technique that would create two halves would be employed during the mold making process.

Once the two halves were separated, they were taped together and plaster of Paris was poured into the mold to make a duplicate of the original model. The plaster model turned out perfectly. The picture shows the plaster casting and the latex mold.

What alternative process are you currently considering for your company? Give us a call and let's talk about how we can investigate the possibilities for your process. Contact Ewan Pritchard at (919) 857-9028 or epritchard@advancedenergy.org/ .