Why is it recommended to wipe faces with a damp cloth before applying urethane glue?

The most appropriate choice is related to ensuring a clean and prepared surface for the urethane glue application. Wiping the surfaces with a damp cloth helps remove dust, dirt, or oils that could interfere with adhesion. This cleaning step is critical because contaminants can prevent the glue from reacting properly with the surfaces, potentially leading to a weak bond.

While certain options imply aspects of surface preparation, the correct action of wiping with a damp cloth specifically targets ensuring that any polymerization process of the glue occurs effectively by providing a clean, moisture-friendly environment. Moisture helps activate the urethane glue, aiding in a better and more durable bond once applied. This step significantly enhances the overall effectiveness of the adhesive by promoting better molecular interaction with the substrates being bonded together.