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.
Blue rectangle or square SERVICE signs are a welcome sight for travelers who need a break from the road. We look for these signs to help us find service stations, places to eat, rest areas, phones, and overnight facilities. The handicapped-accessible sign is one of the most inviting for disabled travelers. REGULATORY signs instruct drivers to do or not do something. Click here to see more Regulatory Signs.