Common Painting Problems


Mud cracking

Mud Cracking

 

Mud cracking is presence of large cracks which may cause coating to curl at the cracks.

Causes:

  • Excessive film thickness
  • Rapid drying conditions
  • Topcoat incompatible with previous coats

 

Solution: 

  • Reduce film thickness
  • Allow temperature to cool before application
  • Check compatibility of coatings with Berger
Wrinkling

Wrinkling

Wrinkling is furrows and ridges in the coatings – usually at random.

Causes:

  • Surface of film dries too quickly
  • Previous coat not cures
  • Wet film thickness is too high
  • Topcoat incompatible with previous coats
  • Spray gun technique too rapid

 

Solution: 

  • Allow temperature to cool before application
  • Allow previous coat to cure fully
  • Reduce film thickness
  • Check compatibility of coatings with Berger
  • Slow down gun movement by using slower passes
Fingering

Fingering

 

Fingering is when you see uneven spray fan resulting in alternate thick and thin lines of paint in the spray fan and on the substrate.

Causes:

  • Coating viscosity too high
  • Air pressure too low
  • Worn tip
  • Blocked tip

 

Solution: 

  • Add a small amount of recommended thinner
  • Increase spray pressure
  • Change tip
  • Clean tip
Excessive Spray Fog

Excessive Spray Fog

Excessive Spray Fog is a large amount of spray appearing like a heavy mist as the product is being sprayed.

Causes:

  • Air pressure too high
  • Spray tip too small
  • Spray gun too far from the surface
  • Coating viscosity too low

 

Solution: 

  • Reduce air pressure
  • Use larger tip
  • Move gun closer to surface
  • Reduce amount of thinner added

 

Staining

Staining

 

Staining is a patch, usually dark coloured, that appears in the film sometime after application.

Causes:

  • Sulphide staining
  • Leaching of contaminants already present in substrate
  • Mould/ bacteria growth in or on film

 

Solution: 

  • Use non–mercurial emulsion paint or lead-free alkyd paint
  • Use a suitable sealer coat prior to application of finish coat
  • Ensure paint being used is anti-fungal and that substrate has been cleaned with bleach or fungicidal wash

 

Cobwebbing

Cobwebbing

Cobwebbing is the formation of filaments of partially dried paint particles during spray application.

Causes:

  • Solvent blend too “fast”
  • Spray gun too far from the surface

 

Solution: 

  • Ensure correct thinner is being used
  • Move gun closer to surface

 

Overspray

Overspray

 

Overspray is a very rough surface appearance that can actually be dust on the coating.

Causes:

  • Excessive atomisation
  • Spray gun too far from the surface
  • Spray pressure too high
  • Uneven spray passes

Solution: 

  • Use larger tip size
  • Move gun closer to surface
  • Reduce spray pressure
  • Overlap wet passes by about 50%

 

Pin-holding Cissing

Pin-holding Cissing

Pin-holding Cissing are small visible holes caused by the wet coating recessing from an area of the surface usually randomly located.

Causes:

  • Spray gun too far from surface
  • Porous substrate
  • Coating dries too fast causing air entrapment
  • Contamination in air line
  • Grease/oil on surface

 

Solution: 

  • Move gun away from surface during spraying
  • Apply a mist coat or a sealer coat
  • Use slower thinning solvent (consult Berger)
  • Ensure oil and water filter are clean and working – ensure paint line is thoroughly clean
  • Ensure surface is thoroughly clean prior application

 

Uneven Gloss

Uneven Gloss

 

Uneven Gloss is a patchy appearance on the surface giving uneven sheen levels.

Causes:

  • Incorrect thinning solvent
  • Uneven absorption by the substrate
  • Moisture contamination
  • Incorrect mixing of coating

 

Solution: 

  • Check data sheet and ensure correct thinner is used
  • Apply sealer coat or patch the porous substrate
  • Ensure air supply to pump is dry and moisture is not in surface between or after application
  • Check mixing of paint. With 2 pack materials ensure mixing ratio is correct.

 

Orange Peel

Orange Peel

Orange Peel is an uneven finish giving an unclear reflected image from the surface.

Causes:

  • Paint is too cold
  • Incorrect pressure or tip size
  • Spray gun is too close to substrate
  • Incorrect thinning solvent
  • Viscosity of product is too high

 

Solution: 

  • Warm paint
  • Change tip or increase pressure
  • Alter distance of spar gun from surface
  • Check that correct thinner is being used
  • Reduce viscosity by warming paint or careful addition of correct thinner

 

Sagging(runs)

Sagging(runs)

 

Sagging (runs) is excessive flow of paint on vertical surface resulting in streaks and thick lower edges in the paint film.

Causes:

  • Dirty air cap/tip
  • Wet film thickness too high
  • Spray gun is too close to the surface
  • Tip size is too large
  • Coating viscosity is too low

 

Solution: 

  • Clean tip and air cap
  • Reduce wet film thickness
  • Move spray gun further away from surface
  • Change tip to smaller size
  • Reduce addition level of thinners or reduce temperature of paint prior to application

 

Brush Marks

Brush Marks

 Brush Marks are lines of uneven film build that remain in a film after it has dried.

Causes:

  • Coating is too viscous
  • Paint not worked into surface or brushed out
  • Paint is too cold and will not flow out

 

Solution: 

  • Add a small amount of recommended thinner
  • Brush coating out well with a final light brushing in one direction
  • Warm paint prior to application