When using pH test paper/indicator sticks you should also: 1  Make sure to only use paper/sticks that have not been previously wetted. 2  Wait for the color to stop changing (1-2 minutes maximum) before matching the paper/stick to the color key.
Red and White Regulatory Signs. Red and white regulatory signs tell you about regulations you must follow. For example, the DO NOT ENTER sign tells you there is danger ahead because vehicles will be coming toward you, usually on a freeway off-ramp or one-way street. The WRONG WAY sign may accompany the DO NOT ENTER sign.
Official MUTCD compliant road symbols alert drivers to prohibitions, changing road. conditions, and potential hazards. Find the right road symbol signs below. Aluminum Traffic Symbols that Last. These road symbols are made from durable reflective aluminum that will last outside. for years. These signs wonât chip, crack, or fade and resist chemical wear.