Silicone defoamers: compound, emulsion or powder?

• Record the actual pH, temperature, surfactants, suspended solids and liquid residence time before comparing grades.
• Choose a supplied form that can be incorporated with the available mixing and dosing equipment; confirm dilution stability before storing a premix.
• Measure initial foam height, decay and renewed foaming after repeated agitation, not only the result of one shake test.
• Keep addition point, dosing interval and agitation history documented so that a successful result can be repeated.
• Inspect filters, vessel walls and downstream coated or bonded surfaces for deposits and compatibility defects.

VN-SI-1110 is a 100% active PDMS/fumed-silica compound with a listed viscosity of 20000–80000 mm²/s at 25°C. It is positioned for pulp washing, industrial cleaning and wastewater development. Its viscous, water-free form requires a deliberate incorporation plan; alkaline-process positioning does not establish a universal pH or temperature limit.

VN-SI-1113 is an emulsion with a nominal silicone concentration of 30%; this is a description value to verify against the current specification. VN-SI-1111 is a powder with listed 90% active content and silicone-resin/filler composition. The powder, emulsion and compound should not be exchanged on equal supplied weight without checking the definition of active material and the resulting dispersion.

Run a baseline and a benchmark alongside the candidate in the same process liquid. For circulating systems, repeat pumping or agitation and record recovery of foam over time. A fast initial collapse followed by rapid refoaming suggests that addition timing, dispersion or persistence needs attention; simply increasing the first dose may not solve the operating problem.

If foam control is acceptable but deposits appear, assess the dilution route, droplet distribution and compatibility before changing the process. If a coated surface develops craters, test the full finishing sequence rather than measuring foam height alone. For dry blends, examine powder distribution and the wetting stage when water is introduced. Retain the tested liquid composition and mixing sequence as part of the approval record.