Dip Coating

Dip coating is simple but obtaining a good quality of coating can be difficult. As discussed above, the physical properties of coatings, such as viscosity, density, and solids content, are influential, as is the rate of withdrawal. There are several practical ways of applying dip coatings. They partially depend on the size of the parts and the number being coated. Large numbers of small parts, such as garden shear blades or fasteners with threads to be coated are typically hung from an overhead chain. The chain is loaded with the parts automatically or by hand. The parts can be cleaned by dipping in a solvent bath or by passing through a hot oven.

The parts are dipped into a constant level paint bath and removed slowly. The conveying line must move very smoothly to obtain the most uniform coverage. A drip of coating material often remains at the tips of the item being coated. This is removed by letting the bottom edge graze a wire, which removes most of the drop.

It is necessary to:

• monitor and remove surface bubbles that sometimes form,

• take care to avoid contamination,

• monitor viscosity changes due to evaporation,

• agitate the dip tank if the coating tends to settle,

• monitor the coating quality if materials are shear sensitive and the coating bath is agitated.

Updated: August 13, 2015 — 8:56 pm