In the hand layup process of fiberglass products, when the ambient temperature is below 15 ℃, in order to ensure the normal curing of the resin and prevent process problems, the following heating measures and precautions can be taken:

Heating equipment:
 Use electric heating blankets, hot air fans, or infrared heaters to heat the mold and working environment. These devices can quickly increase the local or overall temperature, ensuring that the resin solidifies at the appropriate temperature.
 Heating elements, such as electric heating wires or heating tubes, can be installed inside the mold to adjust the temperature and achieve uniform heating by controlling the current.

Environmental sealing and insulation:
 The work area of hand lay up molding shall be closed, and thermal insulation materials such as foam board and thermal insulation blanket shall be used to reduce heat loss and improve the ambient temperature.
 Ensure good ventilation in the work area, but at the same time, avoid direct cold air blowing towards the forming fiberglass products to prevent a sudden drop in local temperature.

Resin preheating:
 Before mixing the resin and curing agent, it can be preheated to a suitable temperature, generally 5-10 ℃ higher than the ambient temperature, to improve the fluidity and wettability of the resin.
 Pay attention to controlling the preheating temperature to avoid premature curing or performance degradation caused by resin overheating.

Temperature control:
 Accurately control the heating temperature and rate to avoid adverse effects of temperature fluctuations on the resin curing process.
 Use a thermometer or temperature control system to monitor the working environment and mold temperature in real-time, ensuring that the temperature is within the set range.

Safe operation:
 When using heating equipment, strictly follow safety operating procedures to prevent safety accidents such as electric shock and fire.
 Ensure good ventilation in the work area, prevent the accumulation of toxic gases, and wear necessary personal protective equipment.

Process adjustment:
 According to the actual situation after heating, adjust the resin ratio, coating speed, and layer thickness and other process parameters in a timely manner to ensure product quality.
 Pay attention to the curing condition of the resin, adjust the heating time and temperature in a timely manner to avoid insufficient or excessive curing.

Material adaptability:
 Considering the impact of heating on the properties of resins and reinforcing materials, select raw materials with good high-temperature resistance for production.
 Evaluate the performance changes of the product after heating to ensure that it still meets the design requirements and usage conditions.

Subsequent processing:
 After demolding the product, necessary post-treatment should be continued, such as trimming, polishing, and painting, to improve the appearance quality and durability of the product.
 Regularly inspect and maintain heating equipment to ensure it is in good working condition, improve production efficiency and product quality.
 In summary, in the hand layup process of fiberglass products, when the ambient temperature is below 15 ℃, taking reasonable heating measures and paying attention to relevant matters are the key to ensuring product quality and smooth production.