Solutions – Porosity is best addressed in three ways: using proper spray techniques and spray equipment control settings to control the film thickness and material atomization, using proper mixing practices and using fresh materials.

  1. Cracking – Cracking describes the breaking of gel coat film from mechanical or thermal forces. It results when the gel coat film is too thick in high stress areas or when the laminate is too green or not strong enough to support the gel coat when the part is stressed or damaged, such as during de-molding, handling during assembly or use in the field. Cracking can also occur if the part sticks during de-molding or when the part is stressed at extreme low temperatures. Solutions – Cracking can be mitigated by using proper spray techniques and spray equipment settings to control the gel coat film thickness or by redesigning the laminate or product for proper composite thickness and reinforcement in high stress areas. Cracking can also be reduced by reviewing mold release selection and application practices and reviewing gel coat suitability for the part and process.

In addition to understanding potential gel coat problems, it’s important to ascertain whether they are special or common cause issues. Special cause issues don’t fit a pattern, happen infrequently or are isolated to a specific process. They can often be addressed with an immediate corrective action, like switching to a fresh batch of gel coat, mixing a drum or repairing/calibrating a piece of equipment.

Conversely, common cause issues happen more frequently and/or occur with multiple operators, on multiple parts, with multiple equipment setups or under multiple conditions. Common cause issues are likely to need more systemic solutions, like additional training, engineering changes or modifying a process or procedure.

Another important aspect of troubleshooting any problem is determining if it is related to the raw material or to the process itself, which can help you determine if the issue is special cause or common cause. Raw material issues can arise with gel coats, mold release agents, initiators, buffing compounds, patching aids or other materials applied to the mold that can impact the quality of the gel coat film. Process-related issues involve people, methods, material selection and qualification, equipment, molds, calibration and environmental conditions.

Finally, when you troubleshoot an issue, it is best to make one change at a time in order to identify the effectiveness of each solution on its own. Making multiple changes at a time, unless carefully controlled for, can lead to confusion and worse results. And remember that suppliers are the experts, so reach out to your material supplier for additional technical support.