Anyone who has bought platinum catalyst has surely seen descriptions like this in a supplier's product literature: low platinum content, medium platinum content, high platinum content—or a unit that sounds impressively technical: ppm. Many newcomers in the trade take one look and feel dizzy: What on earth do these numbers mean? Is higher better? Today we'll thoroughly clarify this most basic yet most confusion-prone question.

I. First, Understand the Word "Concentration"

As explained in the previous article, a platinum catalyst is essentially a "solution" made by dissolving platinum in a carrier. And since it's a solution, it necessarily comes in "strong" and "weak" versions.

Here's an everyday analogy: frozen concentrate juice. Buy a bottle of concentrated lemon juice, and making a big pitcher of lemonade takes only a tiny splash. Buy the ready-to-drink version that's already diluted, and you'll need to pour nearly half the bottle to get enough flavor. Both can make the same lemonade—the only difference is how much you pour and how much you pay.

Platinum catalysts work exactly the same way. Suppliers "dissolve" platinum in a siloxane carrier and can make it very concentrated—lots of platinum, little carrier, so a small bottle goes a long way—or relatively dilute—less platinum, more carrier, which makes weighing easier. The ppm marked on the label translates to "how many parts of platinum per million parts of catalyst liquid." The bigger the number, the more concentrated the "juice," and the more "substantial" the platinum.

So the first concept to establish: ppm measures "concentration," not "performance." Given one low-concentration and one high-concentration catalyst, as long as the "pure platinum amount" added to the silicone is the same after converting for concentration, the catalytic effect is theoretically identical. Choosing between them is never about which is more powerful—it's about which suits the way you work.

II. How Concentration Affects Actual Use

With the "juice" logic clear, let's look at which scenarios suit which concentration.

High-concentration products are like frozen concentrate: they suit "bulk, precise, automated" settings. Formulation plants for liquid silicone rubber (LSR) injection molding and production lines with automated metering pumps tend to favor high-concentration products: the dosage is small, so less carrier enters the system and formulations are easier to keep "clean"; a slight movement of the metering equipment delivers an accurate dose; and shipping and storage volumes are small, so logistics cost per kilogram of effective platinum is lower. Its drawbacks are equally plain: the dosage is so small that a slight error in manual weighing has an outsized effect—one shaky hand can cause a noticeable curing fluctuation; and high-concentration platinum liquid is dark in color and expensive, so buying a large quantity ties up capital.

Low-concentration products are like ready-to-drink juice: they suit "small-volume, manual, frequent-take" settings. Small-batch producers, lab prototyping, and small plants mixing on site find low-concentration products far more forgiving: weighing errors get "diluted out"—a little more or a little less has minimal effect on the final platinum amount, so the process tolerance is wide; and they disperse more easily into the silicone. The price you pay: you're adding much more "carrier" into the system, the formulation gets diluted, and it's less suitable when you're aiming for ultra-high performance or extremely low volatiles; also, more than half of what you bought is "the water in the juice"—you're paying freight and packaging for the carrier.

Medium-concentration products sit between the two and are the most common form on the market—easy enough to weigh, without bringing in too much carrier. For most ordinary addition-cure silicone plants, medium concentration is usually the safest starting point.

III. Three Practical Criteria for Selection

Building on the reasoning above, here are three judgment guidelines you can apply directly when selecting.

First, look at how you add it. If you use automated metering pumps or high-precision dosing equipment, favor high concentration—the equipment's precision is a match for concentrate, and efficiency is highest. If you weigh on a manual electronic scale and stir by hand in small batches, favor low or medium concentration—human hands aren't that steady, so let "tolerance" compensate.

Second, look at your formulation's purity requirements. For food-grade, medical-grade, or optical-grade products, where you don't want extra low-molecular-weight carrier in the system, lean toward higher concentration. For ordinary industrial parts, a bit more carrier does no harm—lean toward medium-low concentration, where both cost and handling are comfortable.

Third, always reconcile by "pure platinum amount." When changing suppliers, models, or concentrations, never simply carry over the old dosage. First convert both catalysts' concentrations clearly: old dosage multiplied by old concentration equals how much pure platinum; then calculate how much of the new catalyst is needed to supply that same amount. Get this conversion right, and switching models won't derail you. This "reconciliation" step deserves a place in your workshop's material-change SOP.

IV. Two Common Misconceptions

Finally, let's correct two widespread misunderstandings.

Misconception one: "Higher concentration means more advanced." Not so. Concentration is merely a "concentration multiple"—it carries no information about technical sophistication. A catalyst's true caliber shows in the quality of its platinum active centers, batch consistency, and resistance to poisoning—none of which is inherently related to the concentration on the label. When buying catalyst, what matters is "is this platinum good at its job," not "how crowded is this platinum."

Misconception two: "A little extra catalyst just cures faster—no harm." As the principles article explained, platinum catalysis is a precise chain reaction. Adding too much doesn't just make it "faster"—it can make the silicone cure so quickly there's no time to work with it, increase internal stress in the part, and even impair aging resistance. And since platinum is priced as a precious metal, extra dosage is simply extra money spent. Catalyst dosage calls for being "just right," and that "right" is usually established by a formulation engineer through testing—not by a casual scoop.

V. Summary

Platinum content refers to the concentration of platinum in the catalyst—the same platinum can be packaged more concentrated or more dilute, like frozen concentrate versus ready-to-drink juice. High concentration suits automated precision metering and high-end formulations; low concentration suits manual operation and small batches; medium concentration is the safe choice for most scenarios. The key to selection isn't "the more concentrated the better," but matching your feeding method and formulation requirements. And when switching materials, always reconcile by pure platinum amount.


Platinum Catalysts MY-PC Series-Products-Mingyi Silicone