Holz has rubbery 73-year Lodi legacy

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After the proper chemicals are mixed into the rubber, forming thesoft workable pieces used in the molding process, they aredelivered to people like Julian Martinez (one of 120 employees) whohas been with the company for 18 years.

On Thursday, Martinez was molding pressure compensation bladdersthat are used in drilling for natural gas and oil. The bladders areplaced at the end of a drill string to keep any pockets of gas fromexploding as they are breached.

Martinez sprays a mixture on the large metal molds to keep therubber from sticking — somewhat like Pam cooking spray keepsfood from sticking to your pans. The heat from the molds, rangingfrom 285 degrees to 300 degrees, has to remain constant to make therubber workable.

When the heat outside is teetering around the century mark, thetemperature inside the pressing room can hit 130 degrees. Not aneasy task to bear when a person still has to wear protectiveclothing. Cooling off this time of year is not much of an option,but relief comes in the winter, when the workshops cool to a balmy80 degrees.

"If the metal gets too cold, the rubber won't come out," Martinezsaid.

The rubber is then placed into the mold in a small stack of whatlooks like square black pancakes. As the press is fired up, threelarge hydraulic cylinders raise up, putting 1,500 pounds per squareinch on the mold. Excess air and rubber is squeezed out for fiveminutes, and then the molded product cures from one to two hours(depending on the size and thickness of the rubber product, it cantake up to eight hours to cure).

The molding process, as Smith points out, is like baking a cookie.The dough gets softened, then hardens when it cools.

"Rubber can't melt," Smith said.

After the curing — or hardening — process, the platesare separated and — due to the finished bell shape of thebladder — it has to be removed from the mold by injecting aburst of air into the mold. Safety netting is placed over the mold,which is secured to the air unit, the air is pumped and POP! themolded rubber comes out.

This particular piece, the bladder, has a metal cog welded into oneopening.

"If we have a specialty, it's bonding rubber to metal or plastic,"Smith said.

From there, the parts will be sent through a trimming process toget rid of the excess, unusable rubber. Quality control will makesure each item is up to Holz and industry standards.

As clients come to Holz with new needs and specifications, thecompany's engineers, Ted Cooper (with the company since 1961) andMandhir Singh (a newbie at three years of service), will create newmolds to add to the existing library of thousands.

After years of creating high-temperature ducting, expansion joints(the only product that proudly displays the Holz Rubber Companyname), earthquake isolation bearings and more, it is hard tobelieve long-term employees do not get tired of the process.

George Manzo, a 33-year Holz stock cutter, begs to differ.

"It never gets boring. I'm still here, aren't I?" Manzo said,smiling.