Moisture in the substrate
- Sources of error:
- Substrate flooded with water and dried half-heartedly.
- Hygroscopic substrates wetted and allowed to dry only superficially. Organic materials such as wood need quite some time to completely release moisture from the interior.
- Edges, beads, and other covered areas were not adequately blown through with air and dried.
- Defects in the coating where water finds its way and „cracks“ the surface.
- Polyester or spray filler wet sanded. Polyester materials are hygroscopic and retain moisture!
- Water penetration inside. Water also seeks its way here.
- Water-based coating is wasn’t flashed off long enough. Moisture remains in the coating and pushes to the surface when heat is applied.
- Materials not adapted to ambient temperature. A longer hardener and/or thinner is used when heat is applied.
- Failure Prevention:
- Carry out cleaning procedures with care.
- Do not clean or grind absorbent substrates such as putty materials with water.
- „Blasting“ due to water damage cannot be foreseen
- Check and seal water ingress through sealing seams, screw connections, or welding points
- Thoroughly clean surfaces treated with water and allow to dry. If necessary, also with the aid of IR.
- Repair path:
- Osmosis damage with bubble formation cannot be repaired. In this case, everything except the load-bearing substrate must be removed and a new build-up carried out. In the case of glass fiber composites, it may well be necessary to replace entire components. More on this at another point.
As a general rule, if the material lifts off or even comes loose from the substrate, the coating is removed down to the load-bearing material.
- Osmosis damage with bubble formation cannot be repaired. In this case, everything except the load-bearing substrate must be removed and a new build-up carried out. In the case of glass fiber composites, it may well be necessary to replace entire components. More on this at another point.
- Examples of damage:
- Water seeks its way and remains for an above-average time in polyester substrates or organic materials such as woods, which store moisture like a sponge. When drying later, the moisture penetrates upwards and destroys the surface with the formation of bubbles.
- Water droplets run off from edges or butt joints when there is a breeze. If this happens, there remains only one more drying phase and a new start of the coating.
- Also, the volume in the substrate is increased by water penetration, so the surface cracks.
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