Selective plating and chemical processing depend on one thing working reliably: a mask that keeps solution off the areas it does not belong and then comes off without a trace. Incure Litemask™ 4272 is a light-curable peelable maskant formulated for etch, strip, and electroplating baths. The problem selective plating creates Few parts are plated all over. Bearing journals get hard chrome while the rest of the shaft stays bare. Connector contact zones get gold while the body does not. Chemical milling removes metal from a defined window and nowhere else. Every one of these operations needs a boundary that survives immersion, agitation, current flow, and rinse cycles without lifting. Tapes and machined boots handle simple cylindrical or flat features. They fall short on splines, radii, cross-drilled holes, and the irregular pockets of a casting. Litemask™ 4272 is applied as a liquid, cured into a tough elastomeric film, and peeled off in one piece, leaving no adhesive to clean and no masking marks on the finish. Chemical resistance in practice Litemask™ 4272 withstands chemical etching and acid stripping, including the acidic baths common to chrome and nickel plating and the caustic solutions used to strip failed coatings. The formulation is 100% solids with no volatile organic compounds, so it does not shrink significantly on cure and does not outgas into the shop. Chemical resistance is not only a property of the polymer; it is a property of the applied film. An under-cured layer beneath a thick section behaves like a weaker material and lets solution attack from within. Adequate film build and a verified cure keep the barrier intact for the full bath residence time. Cure paths and dose control The maskant cures under UV, visible, or LED light, with heat and activator options for shadowed regions. The reaction is a radical photopolymerization driven by energy near 365–405 nm. A production process needs two things measured: the delivered dose in millijoules per square centimeter, checked with a radiometer, and confirmation that recessed faces and the back sides of features actually receive light. Because lamp output falls as sources age, a fixed recipe drifts unless intensity is monitored. Batch trays cure under Incure L-Series UV LED flood lamps at a set working distance, and higher-output arc coverage is available from Incure F-Series UV flood lamps. Enclosed batch work fits an Incure B/C-Series UV cure chamber. Application and film build A moderate viscosity lets 4272 be brushed, flow-coated, dipped, or robotically dispensed. It penetrates threads and narrow gaps while still building enough thickness on vertical walls to form a continuous barrier. Multiple coats increase film build where a long or aggressive bath demands it. A wet-film gauge during application is the simplest way to hold thickness consistent between operators. Typical work includes masking shaft journals for hard chrome, masking terminal bodies for selective gold or silver, protecting datum and sealing surfaces during chemical milling, and shielding threaded features during passivation. Failure modes and how to prevent them Bleed-under is the dominant plating defect:…

Thermal spray, hard chrome plating, and chemical etch lines share one recurring problem: keeping the coating off the surfaces that must stay bare. Incure Litemask™ 4201 is a light-curable peelable maskant designed to hold a sharp boundary through aggressive processing and then release cleanly by hand. Where a peelable maskant fits Machinists have masked selective areas with tapes, silicone boots, and hot waxes for decades. Each method struggles with the same geometry: internal fillets, blind holes, cooling passages, and air vents on castings. A liquid peelable maskant is applied over those features, cured into a continuous elastomeric film, and later stripped in one piece with no adhesive residue. Litemask™ 4201 is aimed at high-energy operations: high-velocity oxygen fuel (HVOF) and plasma thermal spray, chromium and nickel electroplating, and acid stripping of worn coatings. The film has to survive grit-blast preheat, bath agitation, and elevated temperature without lifting at the mask line. Cure options and how to control them Litemask™ 4201 cures under UV, visible, or LED light, with heat or a surface activator as secondary paths. The primary reaction is radical photopolymerization of acrylated oligomers, driven by energy in the 365–405 nm band. Two variables govern a repeatable cure: delivered dose, measured in millijoules per square centimeter with a bench radiometer, and exposure of every masked surface to that dose. Recessed pockets and the shadowed side of standing features receive far less energy than the line-of-sight surface. For those regions, a short heat cycle or activator wipe finishes the film so it does not stay tacky. Lamp output drops as bulbs and LED arrays age, so periodic radiometer checks and a controlled conveyor speed keep the process in band. For inline curing, an Incure CDM UV conveyor pairs a fixed lamp head with a known belt speed, and Incure L-Series UV LED flood lamps cover batch trays at a measured intensity. Chemical and thermal resistance The cured film resists chemical etching and acid stripping baths, and the formulation is 100% solids with no volatile organic compounds. For thermal spray masking, 4201 is engineered so the film can be removed after exposure above 600°C during the HVOF or plasma process. That thermal history matters: a maskant that has been heat-soaked becomes stiffer and less extensible, so the film is easiest to peel while it is still warm and before it fully embrittles. Application and film build Low viscosity lets 4201 be dip-coated, flow-coated, brushed, or dispensed by robot, and it penetrates narrow gaps and threads. Film thickness is built with one or more passes and checked with a wet-film comb. Typical work includes masking turbine blade platforms and internal air passages, aerospace hardware headed for selective plating, and automotive parts moving through paint and plating lines. Failure modes to design against Most masking defects trace to one of four causes. Bleed-under happens when plating solution wicks along the substrate beneath the mask edge; an oil-free, clean surface and an adequate cured edge bead prevent it. Incomplete cure in thick sections leaves…