Gels are highly sensitive and tricky to produce. Keeping strict control over temperature and environment is critical for product quality.
The formation of a gel starts at the molecular level far too small for the human eye to see. The raw chemicals used to make the gel, which include monomers and oligomers, are first tested for purity and then for their molecular size. If the monomer is not compatible with the oligomer, they won’t mix together smoothly, and may result in a cloudy gel, or may affect the gel’s curing or adhesion. A gas chromatograph/mass spectrometer (GC-MS) is used to measure both of these properties in the monomer, which is a water-like fluid with a relatively low boiling point. Since oligomers are more viscous (thicker), gel permeation chromatography utilizing a liquid chromatograph is used. Since no two batches of raw material are alike, each one has to be tested and recorded when it arrives at the factory. Then, the ingredients are matched and measured depending on the company’s particular “recipe” it has developed for the gel’s optimum quality and performance.
Next, the ingredients are mixed in large automated mixers that are kept at a constant cool temperature. The heat that is generated during the mixing must be dissipated or it will erode the quality of the gel. Every container the gel ingredients touch must be sealed and meticulously clean. A large “paddle” mixes the gel ingredients slowly so that no bubbling occurs. Mixing takes place for about 1 ½ hours, tests are then performed to make sure the batch is done.
The mixed gel is then ready for bottling. Purified air is used to push each batch of gel into a bottle; each bottle is then weighed, date stamped, and capped.
Because of extensive testing, both on the raw materials when they come in and on the final product, a gel batch takes as long as one week to produce.
These large totes store raw materials that make up the gels when they are first shipped to the manufacturing plant. Made of stainless steel with a mirror finish, these tanks maintain a pure environment for the highly sensitive ingredients.
Chemist Vivian Valenty loads samples of monomer liquid into this gas chromatograph/mass spectrometer (GC-MS) unit. The GC-MS measures volatile substances by heating them until they change into a gas, and then captures and analyzes the molecules. Each batch that comes into the facility must be tested, and a new recipe is formulated for each.
Because oligomers (another key ingredient in gels) are much larger molecules than monomers, they are analyzed on this liquid chromatograph using a technique called gel permeation chromatography. Besides measuring molecule size, the unit also checks for ingredient purity.
Great care is exercised when gel ingredients are transferred into this giant 200-gallon mixer .A temperature gauge is used at all times to make sure the ingredients don’t get too hot as they are mixed. This room is temperature-controlled, and a generator stands by in case there is ever a power outage. Mixers are highly specialized; for example, the mixer next to this one is similar to one used in a restaurant to keep oil and vinegar from separating in salad dressing.
Sometimes smaller batches of gel are produced for research or testing, and this small mixer is used. Again, the recipe for a small batch won’t be the same when it is produced in mass quantities; it must be re-adjusted incrementally with the results recorded until it is just right.
The final stage of the gel-making process is here, where this machine uses purified air pressure to pump the gel into its container, one at a time. This facility can produce 3,000 units per day.
Testing is probably the most time-consuming part of making a gel. In one test, a gel’s shelf life is determined by measuring how quickly the product hardens when exposed to heat. The metal stick stirs the gel until it hardens, and the stirring time is measured. Basic curing time is measured by sliding a gel sample under a UV light. To find out how pure the peroxide in a gel sample is, the peroxide is mixed with potassium iodide and starch. The mixture turns blue; then sodium thiosulfate is added until the blue disappears. The peroxide’s purity is measured by how much sodium thiosulfate is used.
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