Definition - All of these are caused by stresses on the film and substrate.- Cracking - An advanced stage of checking or crazing whereby the breaks in the film are so deep as to expose the underlying substrate. Usually occurs as straight lines, often running with the grain.
- Checking - In between cracking and crazing. Larger cracks than crazing, less total cracks than crazing, but not always seen in straight lines with the grain unlike cracking.
- Crazing - The appearance of minute, interlacing cracks or checks on the surface of a dried film. Usually seen as an extreme amount of tiny cracks.
Causes of Cracking/Checking/Crazing- Improper cure of a coating.
- Excessive build of a coating.
- Over catalyzed product.
- Cold coating, material, and/or environmental conditions during application, drying, and curing.
- Extreme variations in environmental conditions the finished product is subjected to.
Prevention of Cracking/Checking/Crazing- Allow coating to cure under normal room temperature conditions.
- Avoid excessive build (more than 3 coats).
- Apply coating in thin (3-5 wet mil) coats.
- Catalyze at the correct ratio.
- Have and use all coating, material, and environment at normal room temperature conditions. Avoid excess heat, cold, humidity.
- Avoid having the finished product in an environment with extreme variations in environmental conditions.
Possible Fixes for Cracking/Checking/Crazing- Strip and refinish
- Sand and recoat
Questions to Ask- Has the product been altered in any way?
Thinners, retarders, colorants, additives, any other additional adds to the product? - Were there any products (water based, oil based, glazes, stains)used that may have left residual material behind?
- What are the environmental conditions, both during application and cure?
- Have things changed, including equipment and personnel?
- Are the products being used compatible?
- Are the products being used from the same manufacturer?
- Was there any preliminary testing of this system before it was used on a larger scale?
- When in the finish process did you notice the problem?
- Has this problem happened before?
If so, what were the conditions at that time, especially compared to the current conditions? - Has the product been catalyzed properly?
- Where are the cracks located on the finished product?
- Has the finished product been through any extreme environmental changes?
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