What should be done first before sampling tack or binder?

When sampling tack or binder, the first step should involve discarding the first gallon to clear the line. This is crucial because the equipment used might have residual materials from previous use that could contaminate the sample. By discarding the initial gallon, you ensure that the sample taken reflects the current material quality and composition rather than being affected by any leftover substances.

This practice helps maintain the integrity of the sample and safeguards against incorrect testing results that could arise from contaminated material. It's essential in assuring that sampling reflects the actual characteristics of the binders being used in construction, leading to more accurate assessments of their performance.

The other options, while important in their own rights, are secondary to the critical step of clearing the sampling line. Using a clean container is vital to avoid further contamination once the material is being collected. Checking the temperature is necessary to ensure the proper handling and use of the material, as the performance of the binder can be temperature-dependent. Lastly, ensuring the line is connected properly is essential for an effective sampling process but comes after the imperative step of clearing the line.