Edge Marking

Definition

Swelling or sweated edges showing in the top-coat around feather-edge sanded old paintwork

Causes

1] Insufficient drying of filler and/or knifing stopper areas.

2] Swelling layer in the old paint at a feather-edge sanded area where the layer of filler meets the old paint or metal.  Or the feathered edge was not fine enough.

3] Swelling of works primer on new/spare parts.

4] Wrong process used over TPA or NC old finishes.

5] Sanded areas not isolated properly before base-coat and clear processing.

How to avoid

1] Ensure drying times are observed.  Infra Red drying reduces the chances of edge marking by drying the lower layers first.

2]+3] Before painting, carry out a solvent test with an Acrylic or NC Thinner to check for solvent sensitivity.  When sanding ensure that the feather edge is fine enough on the layer being sanded (P80/P150) on stopper/filler, P240 on primer filler see technical information). Do not apply knifing fillers over sensitive paintwork (apply to bare metal only and leave a metal edge). Apply spray filler in light coats to isolate. Use paint with mild solvent properties (e.g. Glasurit Water Thinnable Filler 76-71.

4] Observe correct mixing ratios.

6] Isolate sanded base with light coats of spray filler.

Repair

Sand affected areas smooth and flat. Respray with the correct primer and/or top-coat.