Method of spraying of varnish with viscosity increased by storage - is eased by shear stress application from pump feeding spray gun with liq. from intermediate reservoir

摘要

The varnish (18) and a reduced quantity of thinners (19) are pumped (12) into a circuit with forward and return branches (13, 14) serving an intermediate reservoir (20) with a piston or gearwheel pump (21) which feeds the spray gun (16). A pressure-limiting valve diverts some of the liq. via a return pipe (22) back to the intermediate reservoir. The viscosity built up during prolonged shelf-life is at least partially reduced by short-duration application of shear stress through the pumping action. USE/ADVANTAGE - Esp. with organically pigmented varnish, quality is improved by thinning with min. cost and quantity of solvent addition.