The Making of Latex

What is latex made of?

What is latex made of? The simplest answer: latex is rubber. Typically, it is composed of about fifty-five percent water and around forty percent rubber material.

Latex is the soft white substance found beneath the bark of a mature rubber tree. You may be surprised to think of latex as a natural material, given the strength and man-made feel of so many of its final applications, like tires, rubber gloves, and tennis shoes.

The truth is, natural rubber latex does, in fact, come from nature. Before it is processed, rubber tappers harvest latex from trees using a method that has been passed down for generations.

Where does latex come from?

Most natural rubber latex comes from one species of rubber tree. The composition of latex from different trees varies, but the most common one is native to South America. The tree also thrives in Southeast Asian plantations.

Latex lives just beneath the bark of these rubber trees. When tappers peel back the bark, they disrupt the plant ducts to reveal latex, a milky white substance. From there, they can harvest the latex and send it off to be processed.

How is latex harvested?

The latex harvesting process can only begin once a rubber tree is mature—about five years old. At this point, the tree is ready to start producing rubber.

To tap a rubber tree, tappers remove thin strips of bark. Doing so disrupts the plant ducts, which contain latex. Disrupting these ducts allows the latex to flow down grooves that the tappers cut into the tree. The latex flows down the grooves and into large cups.

Tappers tend to these cups, collecting the latex when they become full and replacing the collection cups to continue harvesting from the tree until it is appropriately tapped.

How is latex processed into rubber?

The rubber creation process begins at the point of harvesting, when they take latex sap from rubber trees.

Next, companies filter the latex so it can be packaged in drums for its next destination.

Once latex is ready to be made into smoked sheets of rubber, companies add acid to the latex. This causes the material to clump. The clumped fluid is then rolled into sheets in a mill. Doing so removes water, so the sheets can be dried and smoked.

Finally, latex is prevulcanized. Prevulcanization involves chemical treatments and gentle heating at low temperatures. Once latex is prevulcanized, it is more convenient to transport. With more heating, the material can now be made into regular rubber.

Synthetic Latex

Of course, not all latex is natural. Some latex is synthetic, composed of petroleum-based chemicals. These chemicals are used to create synthetic rubber polymers, which are clumped and dried, then transported to a manufacturing plant.

The manufacturing plant then mixes the synthetic rubber polymers. Sometimes, they mix in additional ingredients, depending on the end product for the synthetic latex.

The plant rolls the rubber into sheets and cuts them into sheets for further processing. The most common synthetic rubber processing techniques are:

• Extrusion
• Injection Molding
• Compression Molding

During extrusion, you feed the rubber polymer compound into the extruder, which heats it and compresses the material. This is done by the barrel and screw of the extruder. The polymer compound is then forced through a small opening to be vulcanized or cured.

Injection molding involves mixing rubber strips. Using high pressure, they are forced into a mold. Once in the mold, heat vulcanizes the rubber.  

Compression molding starts with preforms of rubber compound. The preforms are shaped to a mold with compression, pressure, and vulcanization.

Latex Material Properties

After processing, latex is an impressive rubber material.

Latex is known for its tensile and elongation abilities, as well as tear resistance and overall resilience. Most common abrasives will not bother latex.

Low temperatures are not a threat, but high temperatures can pose an issue. Above eighty-two degrees, latex can begin to corrode. You can add treatment chemicals to protect latex from corrosion due to heat, sunlight, and oxygen.

It is also best not to use latex alongside petroleum products and solvents. Doing so risks breaking down the latex.

Latex Applications

Latex has a wide variety of applications, ranging from everyday items to more specialized uses.

Natural rubber latex is most commonly used to make items like gloves, swim caps, chewing gum, mattresses, catheters, rubber bands, balloons, tennis shoes, and many other sporting goods.

Synthetic latexes are common in coatings, like latex paint. You’ll also find them in glues, thanks to their ability to solidify as water evaporates from the polymer particles in the latex. Synthetic latex can also be added to cement used for resurfacing and patching cracks in cement surfaces.

Have more questions about latex?

Ace Products and Consulting is excited to answer your questions and meet your challenges. Contact us to find out what we can do for your latex.