In short: Meter the defoamer liquid onto a moving bed of high-absorption silica in stages, stop at the load that still flows, and test the powder for flow, caking and — most importantly — whether it still defoams when redispersed. Sensilchem starts powdering trials with CENSIL 698, with CENSIL 688 beside it, and uses the hydrophobic grade CENSIL 17 for oil-based systems that need stabilising rather than powdering.
A silicone or heavy oil defoamer spreads onto silica better when it is warm and thin. Warm the liquid, not the silica, and keep the blender moving throughout the addition.
Meter a quarter of the target liquid, mix, inspect; repeat. Stop at the first sign of the powder rolling into beads. That is the ceiling for that grade and the working load sits below it.
Let the powder stand for an hour so that the liquid finishes migrating into the pores, then run it through a funnel or flow cup. Flow straight from the blender flatters the result.
Stir the powder into water or the customer's system at the intended dose and run the foam test against the original liquid. A powder that flows but no longer defoams has trapped the active where it cannot work.
Fill jars, hold them warm for one to two weeks, and repeat the flow and foam tests. Migration and caking show up in storage, not on the day of loading.
Report load and flow together with defoaming retention for each grade. The right grade is the one that carries the required load and still defoams after storage, not the one that absorbs most.
That is a stabilisation problem, not a powdering problem, and the hydrophobic grade CENSIL 17 is the route to test. Compatibility with the oil is confirmed on your own system.
That is the usual reason to powder it. Run the caking test on the final dry blend, not only on the powdered defoamer alone.
The material you use now, the formulation or resin, the equipment and the target you need to hit. That is enough for us to say whether we have something worth testing.
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