Some caulks are flexible and meet demanding performance specifications. Others are more durable, and others easier to apply. Consider the needs of your job and the factors surrounding it. Do not cut corners on quality. Reputable caulk manufacturers extensively research their products performance to ensure consistency and reliability.
Most manufacturers provide free technical advice.
Read the product instructions and available technical data sheets. Use the toll-free technical support lines. Application information will vary depending on the caulk formulation and your specific job and environment. Taking time to select the right tool will ensure that both you and your customer will enjoy a job well done both at the time of completion and in the years to come.