What is Ink bleed?
“Ink bleeding” is the term most commonly used to describe the visual effect that can occur when print ink from the surface of paperfaced plasterboard becomes partially solubilised by the freshly applied paint system, resulting in an unwanted imprint or unsightly discolouration from the ink bleeding through the paint film. This should not be confused with the opacity or initial hiding power of the paint itself.
Plasterboard manufacturers use various types and grades of printing ink to label and brand their product. This ink is applied by the manufacturer immediately after production. Some inks are more water soluble than others.
Water based latex paints are the most common type of paints applied to paperfaced plasterboard and therefore it is reasonable to assume that the printer ink used will not bleed or dissolve into the paint film under normal circumstances.
How does it occur?
The effect is more likely to be seen in environments with high humidity levels (such as tropical QLD), or cold and damp environments where the paint curing process is retarded causing the paint film to stay wetter for longer. This will allow more time for the ink to be solubilised and move through to the surface.
Printing inks that are more water soluble will be more susceptible to this problem, particularly when combined with paints that either have a longer tack-free time by design or have a higher level of water permeability. Hence this phenomenon could present itself quite unexpectedly or be more prevalent when using certain paint products and brands of plasterboard than others.
The general circumstances by which Ink Bleeding may occur includes:
- Painting with water based paints in high humidity environments or during wet weather
- Situations where the dry times are hindered by lack of air circulation and/or excessive humidity thereby enhancing the ability for moisture to permeate through the paint film to solubilise the printing ink
- Using plasterboard printed with inks that are more water soluble than normal
- Too much wet edge thinner or latex extender added to the paint on hot days
- Any combination of the above
Generally, the problem can be eliminated by employing a suitable solvent based primer or sealer to seal the affected area, prior to repainting the entire surface with the specified original paint system. Tests should be conducted to determine a suitable primer or sealer.
The effect can be minimised or avoided completely by:
- Employing good air circulation (fans & open windows) to exhaust the humidity build up whenpainting
- Employing air conditioning when painting in humid conditions
- Using a suitable Sealer to seal-off the affected area of printing ink prior to painting
- Refraining from thinning the paint with excess water, wet edge thinner or latex extender
- Painting in less humid conditions
- Avoid painting during wet weather
Related technical advice
'Glancing light' is the term most commonly used to describe a critical lighting condition which exists when light hits a painted surface at an acute angle and casts shadows that highlight any surface irregularities.