painting problems

- Mar 25, 2019-

Paint Peeling to Bare metal

Two conditions exist that must be considered when evaluating paint peeling to bare metal.

1. Prime Paint only

If the product is only prime painted, and peeling has occurred, then poor adhesion between the primer and bare

metal has occurred. This can usually be attributed to inadequate surface preparation before prime painting. The

bare metal must be adequately prepared to ensure good prime paint adhesion.

The door should be completely sanded, washed with solvent and re-primed. The sanding and washing

operations provide an adequate surface to assure good primer adhesion.

2. Prime Paint and top (Finish) Coat

The failure could be caused by either poor surface preparation before prime painting or the use of a non-

compatible finish paint that has reacted with the primer and lifted all paint from bare metal. In either case the

corrective measure would be the same. The door should be completely sanded and washed with an appropriate

solvent. The door should then be re-primed. Lightly sand the prime coat, wipe and finish-paint with a compatible

top coat.

Whenever the door is being prepared for top or finish-coat painting the surface should be cleaned. Use the same

solvent that will be used to thin the topcoat paint and thoroughly clean all surfaces to be painted.

PaInt In taPPed Holes

Both hollow metal doors and frames have various holes that are drilled and tapped. These holes are in various

components such as reinforcements. All of the components are brought together as an assembly prior to the

painting operation.

There are a variety of painting methods manufacturers can use. Some of these methods can result in paint build-

up in the tapped holes of the reinforcements. This build-up can make installation of screws difficult. The build-up

should be removed to make screw installation easier and assure that the screws are properly seated.

The best method of cleaning the tapped holes is to use an actual thread tap which matches the screw thread.

The tap will easily cut though and clean paint build-up and by running it in and out of the hole. If the build-up is

not as great and extra screws are available (or can be obtained) a screw can be run in and out of the hole to clean

minor build-up prior to final screw installation.