Final answer:
When presented with porous surfaces, it is better to try on-scene techniques rather than submitting them to the lab.
Step-by-step explanation:
When presented with porous surfaces, it is better to try on-scene techniques rather than submitting them to the lab. This is because porous surfaces may contain delicate or fragile materials that could be damaged during transportation or handling. By using on-scene techniques, such as chemical tests or visual examination, scientists can gather information about the porous surface without disturbing or altering it.